Intermitent Shock from Shower Handle

The instant Hot Water is grounded back to the villa's panel.

The Instant Hot Water Heater has a "built in" ELCB that does not trip, and it's own breaker in the local panel.

The cold water is PVC pipe, the copper tubing out is earthed at the connection on the Water heater.

There are no "Local Regulations" Tomorrow we will check and see if the offending villas are all on the "same phase".

Shutting down the villas is Not An Option, we did disconnect the Hot Water Heaters that have the problem, and it is very intermittent. Going some times for weeks before showing up, than when checked it is normal.

Just need some of the forums experience and thoughts on possible causes.

In any event I will let you all know when we find the problem which has been happening for almost 2 years, since the villas were built.

No local regulations?...Which is the country?...I am planning to start some electrical business there.

The instant Hot Water is grounded back to the villa's panel. Via the supply cables CPC and a supplementary CPC or just the cable on it's own?

The Instant Hot Water Heater has a "built in" ELCB that does not trip, and it's own breaker in the local panel. It should have an ELCB at the supply panel.

The cold water is PVC pipe, the copper tubing out is earthed at the connection on the Water heater. The copper hot water pipe should have a supplementary CPC, if the pipe work consists of compression or push fit joints the CPC should extend to the shower head.

De-energise the villas that have the problem until their fault(s) has/have been removed. Consult a qualified electrician to chase-out the fault(s) and rectify it/them.

I am the OP. Iam well qualified Engineer. Now do you want to call electrician for rectifying this??...it is shame for me.

Is it always the same voltage? If not it supports Kramarat's supposition that it's a bad heating element. Intermittent condition may be caused by mineral buildup at the fault site on the element.

The problem is intermittent and happens to the guest when they touch the water faucet handle. It is difficult to believe that the water heaters are at fault, maybe 1 or2 but not 6, they are all the same make and model. We will megger the elements to the ground and see what we get.

The reporting of the incidents are hit and miss as it is reported by the guest, some are in the villa for 1 week and it happens only 1 time in that week if at all.

There are no drawings of the electrical system, there is no inspection by any authority.

There are no ELCB breakers at the panel, only on the water heater.

We believe that the problem may be that the ground is being used as the neutral in some villas. They do not mark the wires properly and Ground and neutral are the same to most"electricians" here.

We have run into this problem many times here. The villas are on the beach 10 meters><.

We have also had a problem with the neutral opening on the Transformer pole connection, this caused intermittent power outages and low voltage we found this because the neutral connection "glowed RED at night".

if the problem was there when we checked the it would be easy to find, but it is never there when we check. Only report by guest in villa, and than only 1 or 2 reports in a week or a month.

Yes it has been happening more due to the rains we have had in the last 2 months.

The guests only get the shock when they touch the water faucet. We will also test the ground to the water/copper pipe at the sink/shower.

At some villas they have drive another ground rod!! Does the ground go back to the MDB, we are told it does, but it is a black wire the same as the neutral!!

Fix the problem any way possible, shut down, rewire not an option. They have had many "Experts" foreign Engineers, Electrical Company Engineers, Certified Electricians most on vacation here look at and for the problem, no luck.

Again I am grasping at straws, we have some other tests to do and things to check, but getting an expert doesn't work, they have all given up. Access is also a problem, if customers are in residence you can do nothing until they leave or are out for the day.

We have never been able to make the fault happen when we were there, and it may not occur in that villa again for a month or more if at all.

If we could duplicate the fault we could find and fix it at other villas.

One question, why doesn't the ELCB in the Water heater trip?

We will check the water heaters today and see if the ELCB has been by passed, happened before, reason it trips to often! and is inconvenient.

I will let you know what happens, I need thoughts, options and experience, don't shoot the messenger.

<...why doesn't the ELCB in the Water heater trip?...>

because <...the ground is being used as the neutral...> and the reason for this is <...the neutral opening on the Transformer pole connection...>!

De-energise it before someone gets killed.

They have been disconnected in the problem villas, and it took a threats and mashing of teeth to get them to let us disconnect them, reason "it doesn't happen all the time".

The location is interesting, there is a small river running down the middle of the site.

The ground is built up on both sides of the river which is open to the sea.

The ground and neutrals will be tested today, problem here they are not consistent in the color of the wire and they often change wire color in the middle of conduit.

That's an Idea we will test the ground when the tide is out and when the tide is high.

Others have also driven additional ground rods in some areas, we will disconnect these.

I still don't know why the ELCB's in the heaters don't trip, we could put a GFI breaker at the panel, and try that.

"Others have also driven additional ground rods in some areas, we will disconnect these."

What? They have done this to stop being shocked! I hope you meant only for testing. An extra safety ground is not a bad thing.

What do you mean "shutting down is not an option"? If somebody dies here, you will have a lawsuit on your hands. Is that an option?

You said that there are no ELCB (or better RDCCB = residual differential current circuit breaker), and that they are prone, in your are to mix the Neutral with the Ground/earthing cables. Therefore:

1- You might have hit the problem on the head!

2- The intermittent and unpredictable happening is probably due to:

- The culprit switched branche might be only towards one of the appliances in the villa. Therefore, when this appliance is On, the current flow into the grounded (Neutral) will create a differential voltage due to the earth resistance (you mentioned < 10 Ohms which is too high by any standard !) at the time when the appliance is ON ==> thus the voltage and tingle from the tap.

- The apliance I might suspect would be the Air-Con if there are any and that they might be in use due to the hot season!?

Procedure: Switch OFF all the units in the villa except the Water heaters and experiment measuring the voltage from the tap to a well known earth point.You can also measure the current flow to get an idea of the earth resistance involved.

The experiment involves re-connecting One byOne, the allpiances and running them. Measure the voltage until you start to have some substancial one (like > 20Volts ac). This will indicate the circuits to re-inspect and check their Neutral connections.

Hope this is helpful.

By the way, earthing should not be relied on metal piping only BUT to a REAL earth rod (or pit...) to make sure you have a lower than 2 Ohms resistance.

{ 10Ω & 10A load, ==> 100 Volts, while 2Ω & 10A load would give 20 Volts !!}

>the copper tubing out is earthed at the connection on the Water heater.

How could this be if there is shock potential voltage between the shower handle (and its copper pipe) and the drain, which is presumably the local earth for the 'shockees' ?

It is common practice in the US to use a galvanic isolation union with a plastic bushing that physically separates copper pipes entering/exiting the water heater from contacting the heater's steel or cast iron shell? Is something like this in use?

When they contacted us last month the first focus was the ground at the MDB panel.

The ground rod was buried, If I can not see the ground and its connection I assume there is NO GROUND. We dug up the ground to see the connection, the clamp was rusted and loose, we drove a new 1.8meter 5/8" new copper ground rod next to the old one and ran a new GREEN ground wire, the new ground rod is protected with a PVC above the ground. The neutral was not grounded so we grounded the neutral at the MDB.

Advised the customer to call if the problem happened again. The problem happened about a month later in 2 other villas. (it may be more often but not everyone reports the problem because it is normal in many places!).

My staff will go to the site this morning and do the following.

open the hot water heater, megger the ground to the panel ground, the heater ground to the copper tubing, the ground to a temporary ground rod in the garden, and the panel ground to the temporary ground rod. We will also test 2 random recepticels in each villa with multi-test analizers.

They will also determine if these villas are all on the same phase of the incoming 3 phase power.

They will take photos of the electric companies transformer from all angles as well as check the connections with a thermal scanner.

Photos of all tests will be taken to back up the recorded readings. To many photos are no problem, not enough are always a problem. We take a photo record before, during and after each job or test. CYA!

We are ordering an Elite Pro power analizer as we are running into these types of problems more often now. We also need a TDR, any suggestions on a simple, low cost and reliable one would be apperciated.

I will let the forum know the results of our tests and observations, good or bad.

No, we do this now when we install water heaters, the proper plastic pipe and fittings have just become avaliable here.

If the copper hot water pipe really is earthed (which I doubt), then maybe the drain is floating, isolated by plastic somewhere along its run, and the shock voltage comes from a buried power cable whose insulation leaks. When the soil is wet enough (you mentioned it occurs during heavy rains) the leakage voltage makes the drain 'hot' and when the human in the shower touches the grounded faucet handle, they get shocked.

This is too improbable from more than one location though, which leads me to believe that the copper hot water pipe is electrically floating.

I am an electrician in Australia & I believe the problem is in the earth & neutral wires.

I think as well as the posibility of the 2 wires being transposed at the water heater or it's supply board there is likely to be the same incorrect connections in power &/or light circuits in 1 or more of the villas thus causing the intermitant fault only when the light or appliance is plugged in & opperating & useing the earth as a neutral thus creating the increased potential on the earth being used instead of a neutral.

I would sugest that 1 vila at a time you disconect every light, power outlet & appliance & correctly identify the earth & neutral at each point back to the vilas sub board & to other points in the vila with an ohms meter & mark / identify the earth with green tubeing at each point for future reference.

If the neutrals & earths are mixed up & interconnected after the ELCB it will render the ELCB useless & of no benefit & will give a faulse sence of security

Brett can you explain what you mean here :

If the neutrals & earths are mixed up & interconnected after the ELCB it will render the ELCB useless & of no benefit & will give a faulse sence of security

The only earth to neutral bond should be on the supply/ line side of the ELCB

If the earth & neutral are interconnected or conected in parralell any where on the load side of the ELCB & then an earth fault developes say you touch a live terminal & are holding on to the earth or metal case of an appliance (like some 1 taking toast out of a jammed toaster with a knife) the ELCB will not see this as a fault because the current is still going to the neutral where they are conected together

The false sence of security is the customers staying there thinking they are protected

Ground and neutral should be separate. Ground wire to be connected to an electrode and a ground wire should be connected to all sockets in addition to N & L

I agree with Bud's suggestion.

Isolate the hot water copper pipe from the faucet handle by cutting it and inserting a small piece of PVC or HDPE pipe. This will provide insulation if the copper pipe is transferring the voltage. If the voltage gets up near 100V, you will need to take the villa(s) off line because you might kill a guest.

Then you still have to find the problem and rectify it. I had the same problem in Bali - a similar location to where you are by the sounds of it. Same thing - gets worse when it's rainy season. I'm puzzled that your ELCBs aren't tripping. Are they wired the correct way around - incoming/outgoing?

Anyway the solution in Bali was to install ground rods at the villas and connect the neutral to them. This overcame the problem that the power company had not grounded correctly at the transformer and probably explains your "neutral glowing red" problem.

I don't have to tell you to take this very seriously. You sound intelligent and responsible. If you are getting heat from management, blame the power company at the same time as reminding them that the death of a guest is the death of the complex. Believe me, a guest was killed in Bali a couple of years ago as he stepped into the swimming pool and that was the end of that villa complex: both staff and guests refused to come. Consider beefing up your grounding at you main incoming panel.

My staff is back with data and photos, the 3 villas in question they found wire "pits" (hidden in the garden plants) where the wiring is underwater during rains. The connections are twisted and taped and all have overheated. One villa has it's own ground rod (buried in cement), the one to the MDB has been disconnected.

There are to many problems to go over here, just have a look at the pictures "I see what your problem is now" no one has ever looked in these hidden "pits" On one villa the ground is jumping between 10 and 1000 ohms about every 30 seconds.

No connectors or wire nuts just twist and tape.The "pits' are located behind the villas and are at ground level, when it rains they fill with water, when it stops they drain fast as the soil is sand. hot, neuteral and ground all swimming in a common pool connected to a 100 amp 3 phase breaker in the MDB.

I will now write a report, repair the connections properly and have the sides raised.

This will solve the problem till the next time.

yes we did find the neutral connection on the transformer was very hot where it was spliced to the galvanized pole neutral. They will repair it in the next day or so.

Thanks to everyone for the suggestions and advice, here we need to think outside the box most of the time, always look at what you think would never happen, it usually does or is the problem.

the

A little more information about how often the problem happens when it rains may help. Every rainstorm, only heavy ones, how long after the rain starts does the problem appear, how long does it stay after the rain goes? I realize I am wandering around with my response (late past my bedtime), but check it out. Hypothesis is generally that one or more ground rods is actually connected to a live conductor or other 'thing' (distribution wire, whatever) is causing a current flow through the earth when it rains. I think you have to decide where ground is and make it the reference point to debug this problem. Make a very long set of test leads for your meter, even if you must get a 1000' or longer roll of wire! Connect one end to the ground/neutral connection at the transformer since this is (presumably) the reference point. Then you can use the other meter lead to measure the voltage at the drain, copper pipe, water heater, etc. Perhaps try inducing come current into these things to measure the voltage drop and calculate the resistance of the various pieces to ground. (this will work best if you run 2 wires to the ground point: 1 to carry the current the other to make the measurement, like a 4 wire meter connection). 12V battery to do this ought to be fine for things that are connected up from fractions to many K ohms. One other thought, if you use an oscilloscope for the meter, you can compare the phase of the villa with that of the leakage and figure out which phase is causing the problem. OK, I remember that you are never there when the problem happens. Use the megger to check the drain pipe to ground connection or other 'connections' that don't show up with the current test? I like the suggestion that perhaps the drain pipe is 'lighting up' the tile floor. My thought is that the copper piping is actually grounded (run the current test above) and, again, the floor is getting hot, perhaps through the drain pipe. Something is perhaps using the ground as a return path when it rains and is made conductive? Ha! Maybe some location (or many locations) has hot connected to a ground rod that 'lights up' (creates a potential difference across the soil that can pass some current) the soil when it rains. Swimming pool motor? Outdoor lighting? You said hot and neutral are swapped all the time. The meter setup I described will help you find this. The fact that the ELCB doesn't trip indicates that the hot water heater power is not involved here, only as a ground connection through the pipe which the breaker does not detect. Long range metering, measure the robustness of the ground connections, see what is tied where (like the green sleeve marking technique, actually mark all 5 wire types if you can (ground, neutral and 3 phases), voltage measurements (even dry, maybe some stray voltage can be measured with a meter). Don't lose your enthusiasm to find this! You will find it with logic and because there is only one law at work here: E=IR. Does the best suggestion get a trip to the villa for a vacation? Ha ha! Good luck, Hugh

< .5 ohm would be a minimum. Have proper earth, have no problem.

Love to live in a place with no "Local Regulation". Does that mean you don't have to do the job "RIGHT"

Don't you have a "local regulation" to do it correctly., your own "regulation between the ears"

She'll be right mate..!

We always do it right, we follow the NEC when ever we can, it not possible and/or dangerous we Don't do the job! Some customers insist on unsafe installations or fittings and we refuse to do these Jobs also.

As you can imagine most of our jobs are repairs like the above.

A shock hazard exists when there is a difference in ground potential.Make sure all cold water pipes are bonded directly to the ground rod, as well as the neutral bonded to the Ground Rod.Back in the 1960's the telephone companies were required to bond any house where a phone was installed to prevent a/c back feed into the phone line.This also eliminated intermittent shocks from spigots,etc.It is now a requirement of the NEC on new work,or rework of old buildings.Relying on the metal pipes to be a continuous reliable ground conductor is not allowed.

Sounds to me like the tile floor,when wet, is a better ground than the water pipes.You have a loose or inadequate ground/bonding system.

If all grounds are at the same potential, there will be no shock hazard,therefor all grounds must be connected/bonded to a SINGLE point,so there are no alternate paths for the current to follow.Use a #6 AWG or equivalent conductor, and make sure the clamps are designed for the application.

HiTek

many are on the loose ground/inadequate ground story. A couple of notes: if the rest of the system was 'right', i.e. hots and neutrals were connected correctly, not tied inadvertently to a ground rod or pipe, there would be no 'need' for the safety ground connection, or at least there would be no safety ground current and no way to induce an 80V drop anywhere. If indeed there is a loose neutral somewhere, causing ground current to flow, and if the ground were intact, there again isn't any way to reasonably induce an 80V voltage somewhere. If someone's line voltage were 80V low, a lot of their appliances wouldn't work too well also, I suspect! So, I am back to my theory that there is/are a hot connection(s) to the earth somewhere, inducing the voltage through the soil which is lighting up the drain pipes. Make the long wire meter and do some measurements back to the transformer or whatever distribution panel makes sense (either villa by villa or the main beast). Remember the symptoms: Rain causes an 80V potential between pipe and floor. One of those two things is moving to 80V off the other when it rains. Hugh

It might help to look at potential insulation damage on the electrical wiring that would leak current when wet. I would check any wall / roof penetrations of the electrical service. If you place the wet roof at 220V (caused by the electrical leak) and the ground at ~0V, anything in between gets a many volts per vertical meter depending on the material conductivity.

The leak can also come from a faulty AC unit or a light fixture that get wet.

As other cautioned, this can be a dangerous situation. Don't troubleshoot on live circuit since you don't know what is powered. Disconnect the electrical supply from the remote distribution center and use a megger during rainy days to find the leak.

Remember, being a "qualified" engineer doesn't mean that you are qualified to do every technical work. An experienced electrician should be able to help you in this case. You will learn a lot about troubleshooting if you loose the attitude that you are the "Engineer" and know everything... If you did, this problem would have been solved by now.

If your problem is caused Only by your water heaters, it is intermittent, and cannot afford to close any of the villas, then just isolate the power supplying to all your water heaters. Using a properly sized Isolation Transformers can solve your problem regardless whether the ground wires and neutral have criss-crossed somewhere in the villas or the any of the heater elements are acting up intermittently!.

We were able to make the problem appear, we filled one "pit" with water that had run off of the garden. (used a hose) when the water covered the wiring the voltage appeared on the tile of the shower to ground it was very low <60 volts.

Filling the "pit" with water, in the "pit" are 1 hot phase, the neutral and the ground under the water in the "pit". The wires are also jumpered to feed another villa next door, but the ground wire is still connected to the Main ground rod for that villa, The THW insulation is badly deteriorated on many wire as is the tape joints from sitting in the water and over heating.

The "pit" we tested was the one with a separate ground rod, the ground rod went between 10 and 1000 ohms when tested after the water had drained.

I have given the management my results and how to fix it and am waiting for a reply.

Again thanks to everyone for the advice and sharing their experiences so we could better understand and rectify this problem.

Sadly the repairs will only be "patches", we will megger and document other "hidden" and potential problems to CYA.

Hi, Good work, although probably not the whole answer as you say, there could be an intermittent floating earth in there as well as the shorts in the pit, I would also be tempted to borrow a Ground Bond tester (with plug in outlet) and test every appliance You can get your hands on, - (so much better than just testing continuity) so at least the appliances are safe, and you may quickly discover some other problems as well. Cheers, Geoff.

I remember as a wee lad getting a significant but not painful shock sometimes when I would touch the garden spigot on the side of the house when in my (wet) bare feet.

Long story, short: The neutral (center tap on the transformer) going out to the pole pig had broken. When the 120V loads were not balanced on "both sides of the fuse panel" an imbalance would appear. The electric company came out post haste when my dad informed them of the dangling cable on the pole. (They were probably very relieved no one was injured and wouldn't sue their butts.)

Double check your connections to the utility.

One more suggestion that is in the same general direction as the others that may be helpful. The key issue is to trouble shoot the problem with the least amount of steps. Based on the fact that there are no code requirements that are enforced or inspected there is a good chance the wiring was accomplished by a layman with limited knowledge regarding grounding and the difference between the hot and neutral wire, assuming as long as you have two wires and the appliance works, end of story.

The hot wire from the supply panel is reversed with the neutral wire so the whole unit or a good portion of the unit is reversed combined the with a ground rod driven in sandy soil located a good distance from the transformer is the problem, based on the information you have given.

What do you do the find the problem is if the building has an equipment ground or a bare ground wire going to each outlet, disconnect or remove all light bulbs open all the circuit breakers disconnect all neutral wires at the panel now take an ohm reading between all the wires on the circuit breakers to the bare ground and neutral wire there should be no connection or it should be open between any of the wires. ( sure to turn off the main breaker) then turn off of the individual circuit breakers before making the checks. If you get a reading you will have check one outlet at a time until you find the reversal.

Be sure the ground is 6' long with a good tight clamp.

Hope this helps,

Roy