Copper Plumbing Failure Due to Broken Neutral?

I think you're chasing your own tail.

Copper wire and plumbing will last a lifetime conducting electricity.

Do you have a water leak?

Is it your hot water line running from the heater through your slab and back up into your house?

Is it leaking under the slab?

Your hot water plumbing is subject to rapid thermal heating and expansion every time you turn on the water.

The ground under your house is cool year round. So is the pipe until you turn the hot water on. Then rapid thermal expansion!

You may have a puncture in your hot line where it goes through the ABC under your slab.

I appreciate your valid questions. The answer to just about all of your questions is Yes. Copper, if it has a healthy return path (Neutral line functioning as designed and returning voltage to the transformer) is not under stress. My Neutral (from the transformer to the main connection to my home, 100 feet away from the house) has been broken (cause undetermined, but the power company installed a temporary 1" cable above the ground until crews can replace the underground line) for several years. Pinholes developed around touching copper pipes under the slab (about 10 feet from the original "ground" connection - behind sheet rock to the breaker box) causing substantial flooding during the 100 year flood here in Dallas, Texas. About 50% of the type L copper routed under the slab has degraded to where it can be deformed by squeezing the pipe by hand. The electrical charge on my water system was discovered by a plumber who was shocked to the extent where he could not release his hand from the pipe under the slab, and was saved by his helper pulling him loose. No idea what the current might have been on the pipe, but it was no longer in contact with Earth. I presently have several hundred feet of tunnels under my home so that damaged copper can be replaced through the slab. I also have substantial water damage caused by water coming up through the slab and ruining all my floors. All carpet and wood floors have been removed, but the standard HO-A insurance policy denies breaks under the slab for coverage.

I've been a technician for all my working career, but never talked with anyone about the dangers of a broken Neutral supply to the home. Power company tech informed me it is not uncommon, but all my internet research for blinking lights in the home referred me to checking the ground system - which I have upgraded and accomplished several times.

My guess is that I need to talk with a Materials specialist, as this is a degrading of materials possibly due to something similar to the electroplating process - holes appear to have been developed from spots at copper bends (feeding manifolds).

This broken Neutral was verified by the power company within 30 minutes of my emergency call to their repair techs. The technician also verified I had at least 88 volts on my ground plane. That should be almost zero unless there is a short, right?

Just because something is unique does not mean it is wrong. Seems like each time I contact CR4 with a question or a comment, I get flamed as though I'm an idiot to some - well, there are lots of egos out there. We all learn by asking unusual questions, no? I realize you guys get a lot of mundane questions, but just because I'm not a "guru" does not mean I'm an idiot. All were "new" to this forum at some point, no?

I didn't see any flames, just people trying to offer suggestions.

The additional information you just added might have caused a different, or no response.

Good luck.

<unsubscribe>

Lyn - the flaming comment was directed at the second discussion reply, not the first.

I don't know the ultimate answer for which you are looking, but I KNOW that the neutral going out can cause floating power levels of dangerous magnitude in the house. We lost ours in our back yard, and it turned out to be due to galvanic corrosion where the backhoe operators putting the cable in MORE THAN 35 years before had nicked the insulation. THAT was according to what the power company found when they dug it up, then checked records.

What I found, which prompted my call to them in the first place was that my wifes 2-wire hair dryer suddenly sped up, blew sparks and flames into her hair (no injury, but lots of adrenaline) and then quit, at the same time as all of the then illuminated incandescent bulbs in the house blew, the flourescent fixtures started a LOUD and angy hum/buzz I'd never heard from one, and the refrigerator started walking across the floor as the compressor motor shrieked.

I unplugged everything still on and plugged in after killing the master breaker in the house, then turned on ONE breaker, and the master. Then I checked both legs against the neutral and found normal voltages on the legs, but 284 volts floating on the neutral. The power company seemed to think that wasn't too exciting beyond the fact that the failure caused lethal voltages to float on everything. But they did get excited when I showed them that the "skin" of the refrigerator was floating at 284, also. At that point they nearly made us evacuate, but when I promised them all power was back off, and I had NO intention of turning it back on, they would have to do that after they found/fixed the problem, they let us stay on. Then when the outside crew found the break, and fixed it, everything went back to normal.

I don't know for certain about your circumstances, but the power company said the corrosion occurred most likely because of salts in the soil, and occasional dampness because of poor drainage, coupled with the circulating currents always present in the earth.

That sounds like it might fit your case, also, but I could not be certain. I do think a materials engineer is going to be use, if he/she understands galvanic corrosion as in your case.

If your plumbing is providing your ground path for your structures, then the "floating voltage" is probably returning to earth through that plumbing, which would definitely count as a source of galvanic current.

Sounds like you have a house wired before 1960, like the one I grew up in. No grounded plugs - only 2 prong plugs except for updates by electricians. All the electrician upgrades tie ground to galvanized pipes - fine by code then, to effect an earth ground. Only about 50% of the plugs in that location presently have earth grounds, but it is grandfathered in, by code, until an electrician is called to upgrade. As most of us know, the third (ground, or green wire in the US) became code in the 60's as a safeguard for electrocution safety.

Power company has neither contacted me or completed the line repair in the alley behind my home since last Tuesday. May take 3 weeks, according to the emergency tech who responded last Tuesday.

I feel it is wrong that lives have to be in danger for these problems to get identified and fixed. My power now appears to operate correctly and there are no lights flickering when amperage is drawn, but only due to the temporary line that runs across driveways to the transformer.

The flickering lights were a good "tip" that something was not quite Kosher.....

Some things don't make sense as have been described. You said that a temporary ground line was installed. That should have eliminated any current through your copper pipes. No appliance should be grounded to your pipes, especially the hot water pipes. Is the 88 volts between the temporary ground and the cold water pipe? (what is the reference for the 88V reading?)

What is the relevance of the 100 year flood and your pipes? I would guess that it filled your tunnels under your home.

80 volts sounds like a really bad ground (underground one!).

To what did they reference the reading?

You're chasing imaginary specters....get an electrician...

Don't you mean imaginary vectors?

Maybe ,,,,,maybe not....in any case,, good luck proving anything...

http://criteriumhomeinspection.com/copper-pipe-crisis

In Southern California and Southern Nevada about 10 to 20 years ago there was a huge issue with the copper piping installed in the ground had deteriorated completely. There were 3 or 4 major housing developments that had a class action lawsuit getting the houses re-plumbed with the new PEX plastic piping.

It turns out that the soil was very alkaline and basically ate the copper thru and thru.

It's been a much debated point as to whether AC current passing from a copper pipe will actually result in corrosion at the point of egress.

Obviously any neutral current flowing in the water pipe must at some point leave that pipe to return to the service main. Where it actually does this will depend on relative soil resistivity and other factors such as pipe connection to conducting or non conducting mains etc.

The argument centres around the point that on the half cycle when the current is leaving the pipe, metal will be dissolved and removed, but that metal should be then contained in the adjacent soil and then redeposited on the opposite half cycle. Some debate also contends that the anodic part is stronger than the cathodic, which will also enhance corrosion.

An opposing argument is that Copper Oxide on the external surface of the pipe can, when combined with certain soil pHs, act to rectify the AC to half wave DC which can then cause accelerated corrosion as there is no return of metallic ions on the opposing half cycle. The argument is that this effect also results in elevated voltages on the pipe

With regard to the hot water pipe:- Thermogalvanic corrosion is well understood, and occurs particularly where hot and cold water pipes are electrically connected and localised corrosion then takes place due to the elevated temperature causing a drying of moisture around a buried hot water pipe. The evaporating water can leave behind a concentration of corrosive minerals which can be detrimental to the pipework.

The type of backfill surrounding a pipe can greatly influence corrosion - cinder type fill, which has a high Carbon content can cause corrosion even without any impressed current. Concrete embedded Cu will be cathodic with respect to any soil enclosed Cu, and corrosion can again occur to the buried Cu.

Thank You, Spades. I have not evaluated the soil pH, but it is decomposed limestone - black clay gumbo to southerners. This problem has persisted for close to 5 years - I don't know what I don't know. It did not cause breakers to throw, but I did have lights blinking in time with the washing machine agitation cycle. All high current appliances caused light to dim, but each check for blinking lights steered me to checking my ground rod and ground system. My DVM and plug-in ground device all showed fine.

The house ground had to travel several hundred feet before getting close to the power company transformer. Lines here run underground.

I also wonder how this broken connection has impacted my meter reading, since it relies on current consumption - right? Also, since I have a "smart" meter that provides troubleshooting data to the main office of the power company, isn't a broken Neutral something that should show up after 5 years? Just wondering.

Is your water heater an electric one with electrically insulated heater elements? If so, the element's insulation frequently cracks or breaks and conducts from the break to the grounded tank shell. This can cause many problems such as your and especially when you are taking a shower and touch the shower head or the knobs.

Take a "virgin" sample of your soil to a county soil conservation lab or a commercial lab. Have them test the pH. A high pH will eat the copper pipes away due to corrosion. This is why many codes require backfill with washed sand around the supply lines from the curb.

Just a few minor things that could give you some of the effects you are seeing. Combine them with some of the others mentioned and you may get started in the right direction.

Good Luck, Old Salt

Wow, talk about multiple causes for the same problem! You have the perfect storm of conditions to move copper molecules out of your pipes and into the soil. Your pipes are directly buried in an alkaline slab, the soil surrounding the house is moist and alkaline, then you can add the normal electrolysis that occurs in a water heater (which I'll bet has long ago consumed the sacrificial anode) and with the increased reactivity of warm water. Do you have dielectric (insulating) unions on the water connections, were they bridged? Then you throw in all the leakage current from the broken neutral to accelerate the damage...

Best bet is to replumb the entire domestic water supply using PEX or CPVC tubing if your local codes permit, or at least abandon everything that's buried and run it above grade, it's the only way to avoid the problem in the future. Until then, file a meter reading and floating neutral complaint with your local utility to get that buried section replaced since it's a safety hazard (tell them that you feel a burning sensation if you put your hand on a faucet and the other one on an appliance to get quick action).

I agree, just go with PVC...

Sacrificial anodes are only used in electric water heaters, right? Mine are natural gas, so the copper pipes suffered. The copper was 23 years old, but copper is supposed to last 50 years - perhaps in good conditions. All copper lines under the foundation have been inspected for degradation. About 50% replaced. All that have required replacement were the ones connected to one of two water heaters - the water heater that was tied to the house ground at the fuse box. The primary failure occurred within 10 feet of the water heater - under the slab, where hot and cold copper were close to each other sweeping back up to the first manifold that also sends water to the second floor. I have two water heaters, each serving half of the home. All lines have been replaced on my nickle - my insurance company denied the claim since the break occurred under the slab - standard wording on the Texas HO-A policy. Perfect storm - kinda feel like the captain on that boat.

My gas water heater has a sacrificial anode.

So you look like George Clooney?

<...Sacrificial anodes are only used in electric water heaters, right?...>

Wrong. Outboard motors and metal boat hulls use them as well.

Ram,

I suggest PEX piping, It has been proven out that it works and works well when installed properly and resists almost everything that would affect a copper line.

As for CPVC? I wouldn't use it. It becomes brittle after several years and will cause problems.

I have lived houses that have had all 3 of the mentioned plumbing and PEX is the one that has held up the best.

Hope this helps....

If the neutral fails to/in a US house, it could possibly be dangerous. But I have never experienced this myself....it is considered dangerous in a European house I believe....especially in a 3 phase house, but the neutral is made quite differently....

If GFCI (ELCB for me!) are installed (as any safe person does even if code does not make it a requirement), then I do believe they will trip (hopefully!) as they look for unbalanced loads. But I am not 100% certain.....I cannot see why it would trip though!

But even then, why would current flow via the grounding? You would need to have a failure in the insulation of the device surely.....

Here for example (220VAC 50Hz), all metal water piping and metal baths, sinks and similar should be bonded to the ground, and also to a large underground metal plate, which may or may not be code where you are as well.....

Naturally, there is (should be!) a bond between ground and neutral at some point in a system, especially where 120VAC loads are expected!

Naturally only once.....in my (limited) experience, mostly its bonded outside of private housing, by the local electrical company.....though your local code will specify where....here its done at the 1st main fusebox.

Theoretically at least, there should be no potential difference between earth and neutral in a working installation. Though with many 120VAC loads, it is possible that there is a small difference. Code will say what max difference is allowed.....

I'm not entirely au fait with US wiring codes, but if there is an open service neutral (grounded supply conductor) on a multiphase supply then, depending on the load balance and the integrity of the earthing system, the consumer's neutral can float up as high as phase to phase voltage.

Assuming an MEN or similar earthing system, any out of balance current (full load current in the case of a single phase 2 wire supply) will be carried by the consumer's earthing conductor and it's associated stake and/or water pipe parts of the ground circuit as the only path back to the service transformer.

Depending on the amplitude of this current and the ability of the earthing medium to handle the current flow, a voltage drop of several volts right up to full phase voltage can be developed over the length of that circuit and will be impressed on any metal connected to the earth, including your taps, baths, metal sinks etc.

If that circuit were to be interrupted by say a Plumber replacing a piece of pipe or an Electrician removing the earth bond, then he could be subjected to a fatal shock hazard. If the ground earth is a high enough impedance, then high touch voltages can appear on all earthed metal, even as high as phase voltages.

I don't know about the terminology in Germany - the terms are commonly misused - but generally an ELCB (voltage operated) is a different device to an RCD/GFCI/RCCB (current operated). ELCBs, in the strict meaning of the name, are rarely used in modern installations although it would actually provide better protection in the above event.

Whilst an RCD should definitely be installed, it will not, in the event of an open service neutral, operate to disconnect the supply, and it will not operate if a person makes a circuit between the - now live - earthed metal and a good earth.

It's normal for some current to be carried by the earthing medium as it is, after all, a parallel resistive circuit to the neutral. Two volts drop on the earth is normally considered acceptable, with five being upper limit.

Andy - in this case, the only return path for electricity was ground and that was over 150 feet away. My breaker box ground is good - better than spec, but it is also directly connected to the copper pipe system under the house to insure the plumbing system is also grounded. I have yet to find a ground that isolates the plumbing system from the breaker box, though - they are linked behind the sheet rock walls in the garage.

No "own" earth pit!

Plus (guessing only), your house ground got separated from the incoming mains Neutral/ground. Voila, a nasty problem!! Which that new cable reinstated.

A broken neutral is going to give you a lot of problems.

The 120volt circuits in parallel now become circuits in series with 240 volts.The voltage seen at each appliance will vary according to the other loads connected..

You are a technician,so draw a simple 3 line diagram,with the neutral in the center,carrying the unbalanced load back to the transformer center tap.

From each side to center,you will get 120 volts.

Across both hot wires you will get 240 volts.

This is normal.

Now,disconnect the center(neutral) from the return path to the transformer.

This now places all loads in series with 240 volts,with the voltage on each dependent on the total connected load.

This results in unpredictable voltages at all loads in the house,and can damage everything.

In the USA,all copper plumbing is supposed to be bonded to the neutral,and to a separate ground rod.

If the neutral broke between your house and the transformer,it is the responsibility of

the utility company to make repairs and compensate you for any damaged appliances.

A question come to mind about your water supply:

Is is a public water supply,or does it come from a domestic well?

If a private well,then the water is normally acidic in nature,so imagine a copper pipe with acid on one side and alkaline on the other.

What do you think will happen?

As others have suggested,replace the copper pipe with CPVC or equivalent according to local codes.

Make sure you have a secure ground at the ground rod,and that the main panel is bonded to the ground rod.

Insofar as a standard rate of erosion of the pipe,there are too many variables to make a standard formula feasible.

Refer to the NEC for grounding and bonding requirements or hire a licensed electrician to do the work.

Many localities will not allow an unlicensed person to work on anything electrical except plug-and-cord connected wiring.

Good luck.

Thank You, and each of you who have provided analysis. There is little published information I've found detailing this type of failure, but that would be logical if the public power company were trying to hush discussion - liability issues.

The primary failure was within 10 feet of the hot water tank, which was routed back through the concrete slab, under the house, routed to various locations across the first floor, routed back up through the slab and manifolds used to send the hot and cold to other locations. The most severe leak (which flooded and ruined well over 1800 sq ft of carpet and wood floor) began in earnest at the apex of a 100 year flood here in Texas where the ground was 110% saturated for several weeks. Any rainfall prompted flood warnings and we still have (two months later) rivers and tributaries at flood stage, as practically all the lakes in Texas were well above full and slow drainage continues to drop lake levels to normal.

PEX was an initial consideration and work had begun to replace lines under the slab, and through the slab, with PEX for hot and cold. That began before the issue with the broken neutral was discovered and well after hundreds of feet of tunnels and holes in my slab (and walls) where all copper feeds through. The Master Plumber, though, changed the replacement lines back to copper after reviewing the mechanical stresses of my soil and determining that too much stress would be placed on both connectors and slab penetrations. Copper, he said, is more forgiving and longer lasting under these conditions. I agree. PEX, above the foundation slab, is hard to beat, but could more easily be damaged at wear and stress points. Also discovered I had QEST plastic line running from the meter to the shut-off at the front of my home. That also required replacement and PEX was used for that run. Major technical issue (QEST plumbing lines) for Shell and their R&D that is now illegal for plumbers (in Texas and probably everywhere else) to touch or repair - no approved parts available and lines have to be replaced when encountered.

The TXU (local power provider) Emergency repair tech was here in less than 20 minutes after my call for help last Tuesday. He disassembled the meter on the wall and attached analysis equipment. He informed me there was at least 88 volts on my ground (earth) of the 4-wire supply (two 120VAC, one neutral, and one ground - earth) and that the neutral was not working. He also told me of a call he got last week where an electrician charged one woman $15,000 to rewire her home for the same issue, only to complete the rewiring job, clear the check and then inform her she needed to contact the power company to complete the repair. He indicated that broken neutral lines occur with some frequency (forgive my pun).

Attempting to troubleshoot this dimming of lights issue, over the past 5 years, all internet references pointed to the earth (ground) being the culprit. I have even added a second 8 foot ground rod trying to improve the earth ground back to the breaker box, to no avail. Perhaps if I had gone past page 10 of my research I might have found a reference to the power company neutral also creating similar problems, but it should be easier to find.

My plumber also discovered that the same 88 V electrical potential was on my natural gas line feed to the house (next to the water heaters in my garage) where the original electricians ran a ground wire from the pipes feeding into the water heater (the one connected to the failure 10 feet away) back to the 200 Amp breaker box - not to a dedicated ground for the plumbing. I'll have to check the codes for that issue. Thank God my gas lines are not leaking.

I have water supply from the city - no well. With the plastic supply line from the city meter to the house, they are isolated from the voltage. The return electrical path for my home, up until a week ago, consisted of traveling about 120 yards through the earth back to a ground-based transformer box.

I'm simply reaching out to fellow thinkers with more experience to better prepare my resources of information, especially since there are lots of resources available to the power company to refute my complaint. Working now to identify a proficient legal representative, but want to also be a participant in the entire legal process. I've suffered for quite some time. I also discovered, two days ago, a melted power strip on the floor of an area that was flooded - still plugged in and no breakers tripped. I could have easily been fried when I stepped into 2 inches of water and touched appliances if the neutral temporary repair connect had not been completed the day before.

Internet sources say that the ground and neutral should only be connected (bonded) at the main sevice panel (breaker box).......

However, internet sources for connecting dryers and ranges with only a 3-wire cord, tell you to connect the neutral and ground with a strap on the back of the appliance. This can cause the ground to become hot (as you have in your home).

Also watch out for surge protecting devices.

What was your electricians reference when he said the gas pipes were hot? The water pipes? A ground rod? The neutral?

It was the plumber that was shocked to the point of not being capable of releasing his grip from the "hot" copper water pipe. His assistant, who was also in the tunnel, got him loose. Upon climbing out of one of the several tunnels under the house, the same plumber who had been shocked, tried to use the galvanized pipe gas supply line (supplying the water heaters through the wall and into the garage) to steady himself before climbing out of the tunnel, was again shocked by the gas line metal pipe. This house was originally built in 1992, so it was designed with grounded lines to all connections. The ground to all connections had an 88V+ potential.

It was the power company technician - TXU emergency response - who identified the 88 volts on my ground and the broken neutral, and then installed a temporary (above ground) connection for Neutral from the supply to my house (150 feet from my home) to the transformer 150 feet away.

I am guessing here, but it appears that where you live, there is no requirement for a ground pit (or whatever they are called where you are, one per house.

Its done really early on when building a house here, (I have actually never seen it done, my house is 107 years old!!), but the thick wire issuing from the ground can easily be seen. It has to be at least of a certain physical size and is tested by the local electricity supplier for efficiency (low ohms) to the local power ground.....In some soil types/locations, it has to be made bigger and set deeper....thats all I know....I do believe it can also be incorporated into the foundations....

Here we have basalt (stone reef) sometimes only a meter or so underground, making even even cellars difficult to build/excavate! What effect that has on the earth pit construction (as a name to use), I cannot say!!

This is to ensue that the whole house is grounded and that it can NEVER rise above a few volts over the supply ground.....it seems to work,,,,

Having that would have prevented the 88 volts (not even a true killing voltage but still very uncomfortable!) from getting that high.....

Also, you are not allowed to bond the neutral and earth just anywhere, and only once, here it is in the first fuse box only.....where for further safety reasons I have three ELCB/RCDs (I know the name is old fashioned and maybe not quite correct), to monitor safety problems and to drop that phase if and when required.....only a few milli-amps of current taking the wrong direction and BOOF!! it's off!!

It amazes me that few westernized countries it seems, have these units as a requirement, including here!, still no requirement!! They are not even expensive!!! Under US$20 a pop!!

To me it sounds as though a bad electrician was using your house plumbing as a neutral connection. That MUST be illegal even in the USA. Or you had an electrical device, that had poor insulation and was feeding power into the house ground via its casing.......an RCD or similar would have popped IF installed.....

Here each metal bath/shower/kitchen sink must be individually earthed with their own thick earth cable, back to that earth pit......its not perfect, but its a good start. That is not relying on a single bonding, meaning that most pipes are then basically earthed at both ends.....

Then your local water Ph has wrought the damage in the pipes (which must have been REALLY SEVERE, as just a pin hole would not have done it, the pipe had to be totally gone at some point!), severing the contact to the earth/neutral bond. Or someone cutting a water pipe.....

Ergo. You were "dead" lucky it wasn't more than 88 volts!!!! It could easily have been 120 volts!!! (and if someone says 220, I am not going to argue!!)

Such "accidents" are usually caused when some idiot plumber, working on a badly installed water/electrical system, replaces a piece of copper with plastic!!!

My point is that, there has to be more than one "error" to cause such problems.

If it was me, I would rip out all the old piping and replace it with new plastic and run large sized earth cable to all points, backed up with a good earth pit and ELCB/RCDs.

Read here:-

http://wiki.diyfaq.org.uk/index.php?title=ELCB

http://en.wikipedia.org/wiki/Earth_leakage_circuit_breaker

and here:-

http://en.wikipedia.org/wiki/Residual-current_device

"With the open neutral, the ground is left to provide current. An RCD would not have tripped with an open neutral".

I told him that way back in answer #15, "Whilst an RCD should definitely be installed, it will not, in the event of an open service neutral, operate to disconnect the supply, and it will not operate if a person makes a circuit between the - now live - earthed metal and a good earth."

He doesn't understand the concept.

I do understand the concept, Spades, but I'm also unemployed, 61 years old, and unlikely to be rehired by the semiconductor industry. Very limited budget and everything here satisfies or exceeds all codes - nothing less. I'm simply trying to repair my home so I can sell it and look the next owner in the eye and say "This is a good and safe home, worthy of your investment". "I've made everything I've touched or contracted for repair better than I found it."

Each of us has our own cornucopia of life challenges. Some overlap, but each is different. I continually have to remind myself to try and view the world through the eyes of others. Not perfect, but continually improving. After all - that which I view as perfect today will change tomorrow, no?

I wasn't referring to you CD. Sorry if you misunderstood that point.

If the current seen by the RCD going through the phase line, is not equal and opposite and balanced to the current flowing through the Neutral, for any reason whatsoever it will drop its breaker....

Simple! for a few here, but obviously not all!!

If you look here and read the very first sentence it should ring some alarm bells for you and some others here:-

Residual_Current_Device

Which reads so:-

A residual-current device (RCD), or residual-current circuit breaker (RCCB) is an electrical wiring device that disconnects a circuit whenever it detects that the electric current is not balanced between the energized (line) conductor(s) and the return (neutral) conductor.

What is so difficult in understanding that?

OF COURSE IT WILL DROP POWER IF THE NEUTRAL IS BROKEN!!! IMMEDIATELY.

As long as the "diverted" current through the ground (assuming that other than the missing neutral, the wiring was originally made correctly and to code) exceeds the rating of the RCD, which is usually up to a max of 30ma, not exceeding the timing for domestic installations. See below for Break/Response Time.

IT WOULD BE USELESS IF IT DIDN'T!!

Why cannot several people here understand what is really such a simple concept, or is it simply that I and a few others here are TOTALLY BRILLIANT in comparison?

Break time (response speed)

There are two groups of devices:

• G (general use) for instantaneous RCDs (i.e., without a time delay).
• Minimum break time: immediate
• Maximum break time: 200 ms for 1× I_Δn, 150 ms for 2× I_Δn, and 40 ms for 5× I_Δn
• S (selective) or T (time delayed) for RCDs with a short time delay (typically used in circuits containing surge suppressors)
• Minimum break time: 130 ms for 1× I_Δn, 60 ms for 2× I_Δn, and 50 ms for 5× I_Δn
• Maximum break time: 500 ms for 1× I_Δn, 200 ms for 2× I_Δn, and 150 ms for 5× I_Δn

Here's a simple little line drawing for you Andy.

Note the broken service neutral.

The red arrows show the current flow from the transformer - through the RCD - through the load - back through the RCD - and back to the supply transformer via the earthing conductor and earth mass.

You will note that the current flow through the RCD is indeed balanced on both active and neutral.

The RCD will not trip on a lost service neutral.

As I said, you do not understand the concept.

The egg can be removed with a little soap and water..

You proved me right! You mad another angry post.

That is due to a very poor installation, which your pretty diagram demonstrates fully!!

Why do you always assume you know why? It could have been a cut cable from another builder on another project many years later, but in any case is off topic for what spades was trying to say to you.

STAR LINK MAY NOT BE MADE TWICE
he did not show 2 star connections in that diagram, and please don't shout. (OT again)

If ONLY one star point had been made, the above failure cannot happen

What? A cable can't be cut if you only have one? get real (OT again)

it appears to be in some US houses reading on CR4, copper pipes used as neutral is really horrific to me personally

I don't believe that has ever been done, Certainly not in this OP's house. Again you are making assumptions and not reading what the OP said. You seem not to understand that neutral and ground are connected in the panel. When this <.001% insident occurred, the current was forced to flow through ground, so you assumed the pipes were intended for neutral. shame on you.

go ahead - have the last word as you always do. prove me right again. <unsubscribe>

My father always warned me against arguing with a fool, and you're the biggest one I have seen in a long time. The more you say, the more you display your severe lack of knowledge, particularly on things electrical. I can only imagine that the other forum members put up with your inane rantings for the entertainment value as there is certainly nothing knowledgable or educational in anything you have to say. I'm done with you, l just hope that some poor soul doesn't believe your BS and get themselves killed.

This word, philosophunculist, came up in a different thread just today.

It may have applicability here.

I had to search for its definition.

You may have also missed:

― George Carlin said:

"Never argue with an idiot. They will only bring you down to their level and beat you with experience."

― Mark Twain said:

"Never argue with a fool, onlookers may not be able to tell the difference."

I didn't miss it Lyn, in fact your first GA was from me.

I just failed to really appreciate the depths of this guy's thick headed stupidity.

I assumed that since you lot put up with him that he must have something to offer, I have to say that I have been unable to find any evidence of it in the twelve months that I have been here.

My apologies Standards guy, that post was not meant as a reply to you but to Idiot Andy's post #136.

Which you either did not understand or maybe simply did not read!!! (just to be pleasant!!)

Replying to the wrong post is also an indication......

Thanks for the drawing. The egg in this case may take cleanser and a chore girl or coarse sand paper, but first he has to see the egg. That may take a 12 step program.

Congratulations Andy! You have broken the record for broken records. You have now posted 38 posts that were pushy, angry, or insulting in one thread (there may be more in another thread). I'm betting that you will do one more - prove me right.

Right in what?

Something you do not control in the least?

Big deal, you are easily made happy with nothing!!

StandardsGuy - The only electrician in this evaluation is the emergency tech from the power company. He identified the broken neutral line from the company transformer to the remote connection to my home (a buried box at the property line, which then runs 120 feet to connect to my home meter on the wall by my garage). My clothes dryer (220VAC) is 4-prong, but the clothes washer (120VAC) is 3 prong - I guess the washer neutral and ground are linked, as are all other 3-prong appliances. Interesting observation!

The power company tech disassembled my meter, attached a diagnostic meter in its place, and began checking with a DVM. He then informed me I had an 88 VAC potential on my ground (which was also directly connected from my breaker box to the plumbing at the water heater cold input line). I can only imagine that my gas lines, by virtue of being connected to the water heaters, also had an electric charge. It was the plumber, after being electrocuted under my home and climbing out of the tunnel, put his hand on my gas supply line to steady himself and was again shocked. I cringe at the thought of having electrically charged gas lines through the house into my attic where they feed my A/C heaters!

"I guess the washer neutral and ground are linked, as are all other 3-prong appliances. Interesting observation!"

Yes, as the links I provided said, but only at the panel. Why?

BTW, you should check to see if all neutral wires in the breaker panel are tight. Loose connections there could be part of the problem.

Good point!

Thanks, Lyn. All have egos, but some have limited control or thought of the future.

In learning, there are few absolutes and the opportunities to grow are endless. I've listened to the brightest tell me that the CDs (critical dimensions) in photolithography would never go below 1 micron. We are now printing lines on computer chips that represent about 3 atoms of silicon wide (1000 x smaller than 1984). The unknown is often solved with out-of-the-box thinking, something I have been doing for 30+ years with similar minds. We all have differing life experiences, but those who view the future from a silo are destined to repeat the same errors, no?

I worked in the pwb industry when 3 mil lines and spaces was leading edge.

That company doesn't exist any longer.

Good luck with you problem.

Andy, you're just too easy.

Only for you my love!!!!

In my experience I have had leaking hot water pipes that were embedded in concrete - and may have been due to poor installation - and that was even in a system that had basic pH water.

However, we are currently living in an area that has slightly acidic pH water, and copper piping is a problem - especially with hot water lines. There are formulas for the rate of removal of copper with pH, temperature, and flow rates. The first areas to "pin hole" are the hotter lengths (near the hot water heater), and at elbows.

The cold lines also are prone to corrosion, but at a slower rate.

Companies are installing plastic sleeves inside existing copper lines. I have not seen the process but apparently it is used on larger lines like 1" and up. There are arguments pro and con the technique. The general attitude is to replace the lines with PEX, or thick wall copper lines (buys more time before the problem re-occurs)- but both those require serious renovations opening walls etc.

(As an aside - unfortunately the home I have now has poly B lines - and they are starting to pin hole in the hot water lines. It is a mess, but when I have to open a wall all the poly b gets replaced with PEX.)

That seems far more likely that what the OP posted, thanks.

GW - All pipes that may be in contact with concrete should be insulated for galvonic (?) mechanical vibration, I'm told. My plumbers have done this through all slab penetrations. Looks like rabid woodpeckers invaded my home, but this is what is necessary to insure when I sell, I don't share shoddy work with the next owner. It was the hot supply from the water heater - the one attached to the ground, that had the major failure and flooded my home. The failure increased in amplitude over a 5 day period and created dramatic problems that cascaded problems. Suffice to say, this did little to improve my health.

I have no knowledge of copper pipe failure due to corrosion, but from what has already been posted it seems possible.

One thing to consideris that there could be a serious earth fault (or a neutral break) somewhere else in the distribution system. meaning the whole return current flows throughout the 'earthed' network that could cause a volt drop in the pipes (etc) where those that that passed through your house showed 88 volts when tested.

I agree entirely, but there is to my mind only two possibilities (I am willing to be educated and to hear of more possibilities), as I recently posted:-

1) Illegal usage of water pipe as a neutral return by someone, electrician or uninformed (previous?) home owner.

2) Broken down insulation on a device that used the water pipe illegally as a ground.

Both might/should be against code in most civilized countries.....usually for safety reasons, earthing is done by a third wire, BUT in some countries, here for example, years ago and I believe the USA for a time, only 2 wires were used for everything.....no laws here requiring an update either....

Compounded by the lack of an RCD or similar to safeguard anyone in that house from such possible problems and electrocution.

I feel that all neutral and ground connections need to be on their own cable right back to the fusebox, never any other method....what do you or anyone else say on that?

Here, in my house, it had 2 wires only, so they had a ground/neutral link in every socket!!! which was why I rewired the whole house to 3 wires. This problem could have happened to us as well.....THEN!

When rewiring in the 80's, I even considered using UK 13 amp plugs and sockets for a time, but for insurance cover reasons that was simply not possible....

I find the European system to still be simply dangerous to life and limb, even when fully updated and "on" code.....

"I feel that all neutral and ground connections need to be on their own cable right back to the fusebox, never any other method."

I totally agree. I don't know about present codes, but I have book "Wiring Simplified" based on 1975 codes. It required grounding receptacles to be used in all new construction and GCFIs on all outdoor receptacles and bathrooms. My 1977 home has a ground rod outside below the meter with a 1/2" conduit going down to the rod. I'm not aware of any ground using pipes, but the book shows a picture of a service entrance with a ground clamp to a water pipe!

The OP mentioned getting a lawyer involved. He needs to find out what the problem is before he worries about who to blame for it.

You may have two different problems. I'll agree that the neutral connection is a safety issue and must be repaired asap.

Do you have well water? and have you had it tested? What's the pH?

I have well water that is slightly acidic with a pH of 6.9. Not enough to bother the taste or to cause problems drinking it, but I can't use copper pipe in my house. When I moved in, I replaced all of the copper with brand new type L. Within five years it was degraded to the point where it was crushable by hand, similar to what you describe. Since then I've gone to CPVC and it hasn't been an issue.

You mentioned that you had a plumber working on the pipes. Did he test the water? Most plumbers carry a basic water test kit to test for hardness (mineral content), iron and pH. Might be worth asking him if you have him back. They usually don't charge for the test.

Thanks! I have city-supplied water; good to know the pH. Just tested mine and it is at about 7.

There's no way you should have 88v on your neutral line, broken or not....You obviously have a hot wire touching the neutral, or a shorted fan motor or some other short that feeding line voltage to the neutral....You need an electrician to find the problem and correct it...A new neutral line will do nothing to correct this problem, other than reduce the threat of lethal shock...

I am not that familiar with 220v house wiring as used in Europe and elsewhere. In Canada it is 110/220, with the neutral grounded at the fuse panel. With an open neutral from the utility and unbalanced loads on the circuits, the "line to neutral" voltages can become quite unbalanced (and blow things up). However, the ground conductor may conduct current depending on how good a ground it is, and may have varying potentials due to the varying load current flow.

I just dream I had such a large house that required 2 hot water heaters and was big enough to allow tunneling under it.

Have you inadvertently got the colours wrong and swapped live and neutral wires somewhere in the circuit so that your switches are are switching the neutral wire.

Every thing would appear to work normal, except the voltage measured between neutral and earth would be line voltage. At the same time the voltage between live and earth would be zero.

No wiring changes have taken place since 2000, when I moved in. The problem began (lights dimming) when the power company Neutral stopped functioning (on the power company side - leading to my property) over 5 years ago. The power company technician diagnosed the broken neutral and everything now seems to operate normally during differing loads on the supply - no fluctuations in motors or lights.

I feel that the title of this blog must be wrong.

You have "Copper Plumbing Failure Due to Broken Neutral?"

I personally suspect that there are other reasons as to why a copper pipe has failed, as several others have mentioned, acidic ground being one of them. But normally you would have had pin hole leaks for years as a previous warning....

Also, even if the neutral is broken, which it appears to be as the new overground cable has fixed all the problems, why has it anything to do with your plumbing and shocking the plumbers?

The twain should never meet!!!

Though the plumber may not be 100% innocent, he could have been the final disaster in a "comedy of errors!" so to say.....maybe he cut a copper pipe that served as a neutral conductor for some awful reason, that would fit! What was he doing under your house in the first place?

How about "Plumber cuts copper pipe and accidentally isolates house neutral from mains supply?"

I believe you mentioned having a ground rod in a previous post, if so, then hopefully all your grounds go from all your equipment (including metal baths, showers, plumbing, water heaters etc.) to the ground link in your fuse box and from there to the ground rod.

Also, if you get a ground from your mains supplier (not a given everywhere I am lead to believe), that will also be bonded to that point as well.....(I don't know code for everywhere, who does?)

Maybe your ground rod needs careful checking and re-installing? It should pull any short circuits to ground down to a low voltage, hopefully tripping out any breaker due to over current at least....

Naturally, properly installed RCDs should be even safer and much quicker....

What does your code require?

In your position, to safeguard my family and pets (not forgetting me!) I would say rip out the whole lot and reinstall correctly, testing along the way.

You only live once!!

Best of luck.

• If the neutral connection to a home fails then the priority is to restore the supply, as nothing should work.
• If something still works during a neutral outage, then there is an electrical fault that requires immediate isolation and correction on safety grounds.

<...88+V...> relative to what, please?

I guess the neutral could fail in the main distribution system if it became broken and then shorted to earth such that the return current now flows via the earthed network giving rise to dangerous voltages at various points that otherwise would be near zero.

The problem for the OP is that the fault could be anywhere and no amount of rewiring in his place would fix it.

....and back to the pipe corrosion question - using plastic would appear to be the answer - except that if many others in the area have already changed to plastic - the earth network would be denied the benefit of numerous copper pipes so that the few pipes left behind would carry most of the neutral current - giving rise to even higher fault voltages.

Can you post a sketch showing how that current would flow with regard to:-

....and back to the pipe corrosion question - using plastic would appear to be the answer - except that if many others in the area have already changed to plastic - the earth network would be denied the benefit of numerous copper pipes so that the few pipes left behind would carry most of the neutral current - giving rise to even higher fault voltages.

Thanks for your trouble.

GA for a Good Question.

Where?

Cancelled out by one off-topic to date.

Andy and PWSlack. Sorry, I don't know how to draw pictures on CR4.

I will try to describe the network as I imagine it. Power from the generator goes to the users down the live wire. The current returns via the neutral. The neutral is connected to earth at the generator. There is thus a return path for the current through the earth.

In terms of safety, all exposed non-current carrying metalwork is bonded to earth. (in theory zero volts because the earth resistance is zero - in theory) Thus a fault that causes a short to earth (into non-current carrying metalwork) will send a current back to the generator through the earth network.

Unlike the neutral cable, the earth is a complex network of indefinite series and parallel paths - and anything but zero resistance - such that the neutral current now flowing through earth will give rise to a voltage throughout the earth network.

Now consider a fault somewhere at the user end is caused by the mains neutral being shorted to non-current carrying metalwork when at the same time the neutral is completely broken and provides no current path back to the generator, it means all the current will flow via the earth network.

The resistance of the earth (at the short) might be high enough to limit the current to below trip levels and local individual earth leakage trips would function as normal because for them the correct current is flowing through their neutral - on its way to the point of short circuit.

A broken overhead neutral cable dropping and shorting to the ground could cause it.

The current takes the route of least resistance, which might happen to be via the OP's house through his water pipes and bonded metalwork - hence the voltage.

Does that makes sense!

Great reply, Horace! You have described my situation very well. I have a background in lasers and optics, but less with electronics or electricity - at least I have not killed myself with either. Power here is supplied in the 440V+ range until it nears the home, then reduced with transformers. The nearest transformer is well over 100 meters from my ground system. My neutral was damaged (who knows how or when) between the transformer and the junction that feeds my home. Since that time (over 5 years ago), at the same time I replaced a clothes washing machine in the home, I have noted power issues. All my internet searches directed me to checking my earth ground - none to check the neutral supply to the home. I have invested many hours troubleshooting inside my home and on the earth ground. No change. I even installed a second earth ground pole, as some internet references indicated earth ground poles have a 10 year lifetime. No change to the problem of visual and audible signals from lights and other appliances (change in motor hum) and light dimming at the same time.

Only now, with the temp connection (between the edge of my property and the transformer) do I recognize all appliances and motors working as expected - like I have a healthy power system. A guy that lives alone has fewer opportunities to note problems of this sort.

Perhaps it is due to my limited power demand and other problems have not surfaced before now - who knows?

The fact that my wiring system has functioned without tripping more breakers may be due to a water table flow of underground water within 10 feet of the surface. I have next to, about 5 homes to the east (downhill), a pound continually supplied by artesian flow. Regardless of drought, it has always been full. This could easily be part of the equation of how voltage and current returned to the transformer all this time, no?

"My neutral was damaged (who knows how or when) between the transformer and the junction that feeds my home. Since that time (over 5 years ago), at the same time I replaced a clothes washing machine in the home, I have noted power issues."

Your clothes washer may have bad wiring (open or loose neutral for example). If you meant the dryer, it may have a strap from neutral to ground even if it is a 4-wire cord. I would check both of them out.

Regardless of drought, it has always been full. This could easily be part of the equation of how voltage and current returned to the transformer all this time, no?

Lets say that if you had had a drought below ground, life could have got MORE than just tedious....but maybe your lights might have gone out almost completely an therefore helped you to discover the problems....

But as I have "wittered" on and on about here, a proper RCD or similar would have TOLD you what was wrong, because until the Neutral problem was fixed, you would not have got power on in the house!!!!

PLEASE, PLEASE, PLEASE, GO OUT BUY ONE FOR EACH PHASE (probably only one needed in the USA domestic supply) AND INSTALL IT.......it is "life saving"....

I fail to understand the "resistance" (pun intended) that I see everywhere, here as well, to installing them.....I only know two houses with them, mine and my elder Daughter's house......in spite of the fact that they are now a requirement!!

All UK house builds since maybe 60 years (slightly guessing!), have required them....

A reasonable explanation as to how they work, for the UK but it will apply to most countries:-

electrical.theiet.org/wiring-matters/15/insp-test-rcd.cfm?type=pdf

or here:-

https://en.wikipedia.org/wiki/Residual-current_device

Which covers the USA as well.....

Thank You, Andy Germany. I need to research and learn about RCD - in progress. I was surprised, though, to find the link between my neutral and my earth ground built into my fuse box!

I think that you may find that the supply TO your house may also be linked as well. Twice is in domestic code (as far as I am aware) wrong and can cause EXACTLY the problems you have seen.....it simply fits.

You need the utility company to check the code and to check that out....then someone MAY have to decide which one to remove......

But if other homes are on the same phase, then all homes should have "their" links removed and all rely on the one at the substation/Transformer....is my take, but I could be wrong on that.

Local code must decide....

Andy #84: Maybe my reply is a bit off-topic' in detail, but on-topic in spirit.

All UK house builds since maybe 60 years (slightly guessing!), have required them....

Nearly but not quite: I was employed by a company in Bristol, UK, in 1964 that sold the early RCD's and it was hard work. Earth leakage devices were required if it was not possible to get a 'zero' earth. But they were tripped on current through the earth wire. Typically 150ma.

RCD's we sold were the early 30ma safety type, and although well received by everybody we spoke to very few actually bought them. "...legislation is required...." they all said.

Being young (niaive) I thought a good demo would be to trip the RCD by touching it to show how safe it was. I only did it once! - I got an almighty poke! - but I am still here - so it must have worked - and it still does - I use it in the power supply to my narrowboat.

I have long since been out of the business, so cannot comment on today's exact legislation except to say they must be fitted - and proven to work at the 'safe' current within a 'safe' time scale.

I agree with your safety logic Andy. It is daft not to fit them.

Many thanks for your sensible comments.

It hurts doesn't it, even though it is really low current and a real short time.....?

Any unbelievers should be made to try one out in the same way we did!!

Thanks for the update, the web implied 1955 as the first of such devices being installed in the UK....

A PS to my previous post #114.

The few RCD's we sold back in the mid 60's often kept tripping for no apparent reason. The company got accused of selling dud products - but on test the RCD's proved to function correctly.

Generally the tripping was found to be caused by 'normal' leakage in heating elements in kettles, cookers, water heaters, etc, nothing like the 150mA needed to trip the ordinary breakers, but often enough to exceed 30mA at random intervals.

The 'official' company solution was to tell the customer replace iffy products with ones that did not 'leak', but better, to sub-divided the circuits to reduce the total of collective leakage - 'look at the extra RCD's you will sell'

In practice customers rebelled at the thought. RCD's got bad press. Manufacturers of the 'leaky' appliances didn't like it either.

As I said, selling RCD's was hard work in those days - more like a crusade!

As I said, selling RCD's was hard work in those days - more like a crusade!

Is it any different nowadays, looking here, who is convinced enough to buy one? Nobody is my guess.....

Why is the ground not connected to an earth pit/grounding rod at the generator? This alone is a loss of safety as it references the earth (as in planet) to the ground. No ground rod and it would be possible for the ground plane to have a high voltage when referenced to true ground, though provided generator insulation is in a good condition, you may never notice it....

Why are no RCDs installed, even though code does not always require them for very old buildings? But in the UK where you live, its required for all new builds since the 60's or 70's (from memory!)

How can any sane person NOT used them as a significant "EXTRA" safety device?

Unlike the neutral cable, the earth is a complex network of indefinite series and parallel paths - and anything but zero resistance...

Why is it complex? Please explain what you mean! Also, why cannot it not be close to zero resistance as code requires? I fail to understand how that sentence is correct, except where code has been ignored....

Resistance of any ground connection in the house, to the ground connection at the generator needs to be checked by a good qualified electrician to be within code limits and not tried to be explained away by such a "throwaway" sentence!

Now consider a fault somewhere at the user end is caused by the mains neutral being shorted to non-current carrying metalwork when at the same time the neutral is completely broken and provides no current path back to the generator, it means all the current will flow via the earth network.

How in God name could this happen? Two accidents at the same time? But let us accept that for the moment!

If a single point of "bonding" has been used as code requires, and the ground is low Ohms, as it should be, there could be a low voltage/high current relative to system/house ground, that even if touched, should not be dangerous.

Also, if an RCD had been installed, the supply would already have been dropped automatically, demonstrating a fault to the user(s).

The resistance of the earth (at the short) might be high enough to limit the current to below trip levels and local individual earth leakage trips would function as normal because for them the correct current is flowing through their neutral - on its way to the point of short circuit.

If the ground resistance is well above code allowed levels, as you imply, then some interesting things happen, ovens take ages to heat up, lights flicker and are dim, motors refuse to start and and and.....

Also, if your Earth Leakage Trips are so set, that they do not trip, then they are useless. You write as though only a current trip breaker was in use, which of course will/may not trip as you said.....you are mixing the two up here......your mistake.....two different styles of breaker, both are needed in a good install, or combined units.

Truly good condition, correctly installed ELCBs/RCDs and the like will trip almost instantly in such a situation as you describe. Alerting householder to a problem.

Its still dangerous (without RCDs) I admit, but ignoring all these indications of lights flickering, ovens not getting hot, hotplates running cool etc., is tantamount to gross stupidity.....

Don't you agree?

I appreciate you taking the trouble to respond to my previous explanation, and although you have put an alternative view, and I agree you could be right, I have simply tried to describe a scenario that offers an explanation to the OP that his problems might have nothing to with the integrity of his installation, but due to a external fault such as a neutral breaking and shorting to earth elsewhere (or bonded previously as a deliberate act), that he is the victim of random events not of his making.

The incident has only recently come to light due to equipment not working properly and the OP noticing strange things happening to his water pipes. It is possible that the bonding of the neutral to earth elsewhere has existed for a long time in a distribution network that has evolved from the days before codes existed but only becoming obvious due to a break in the mains neutral cable.

I guess the best answer for this question of plastic pipe replacements is "just how are the sinks, bathtubs, and other plumbing now going to protect you if a charged (hair dryer, curling iron, or radar range) falls into a sink? The primary purpose of a ground to the metalic plumbing system is to save the life of someone in wet environments like bathrooms, kitchens, or laundry areas. Carry the voltage to a safe ground instead of through a human, right? That was the reason to change code in the US, back in the late 60"s, to require an earth ground for all plugs, outlets, switches, and light sockets. Later, code was updated to use GFIC (ground fault interruption circuits) in"wet" areas, as the breaker reaction was too slow to save lives.

While the plastic pipe has its benefits, it will not provide an earth ground and save lives.

I think that you are a bit confused about the differences between Earthing and Equipotential bonding. Technically, if the hair dryer etc. were to fall into the bath with you, and that bath was not electrically connected to earth, then you would receive no shock as there is no path to ground. The device would likely short out and trip the breaker due to internal current flows, but they would not be external to the device. The problem is that we can't be sure that the bath is totally isolated from ground, and therefore the safe option is to purposely connect it thus.

The primary purpose of connecting baths, taps, concrete reinforcing etc together in wet areas is to ensure that there is no potential difference between them - thus the term "equipotential bonding". Those items don't necessarily need to also be connected to the consumer's earthing conductor to achieve this aim, but that is generally also done. This bonding prevents electric shocks from being experienced between different items in the wet area that may achieve slightly different potentials if it were not for the bond.

Some of these potentials can occur through inductive or capacitive coupling which will not trip a GFIC device (no circuit earth leakage) but may be sufficient in amplitude to cause distress to a person especially if they are wet.

By bonding all possible contact points together, the likelihood of shock hazard is greatly reduced.