4-Wire Receptacle Alternative

The neutral wire at some point is grounded....so I don't see any reason to run a separate ground, unless you are meeting some code requirement...In that case I would run a separate ground wire to an adjacent receptacle ground connection if I was unable to run a ground back to the breaker box...I would not connect to a water line in lieu of a proper ground...

I'm a little hesitant to jump in when a UL approved appliance is being modified but I have done this in the past. My old neighborhood has had problems with neutrals opening up. (If you recall in an old posting the fire department was dispatched to a smoke filled neighbor's house due to this.) I'm often barefoot when using the washer & dryer. I wasn't very fond of trusting that neutral was grounded and that all failure modes would result in an acceptable chassis voltage due to the E=IR drop of the neutral wire.

I'm interested in why SolarEagle does not like water pipe grounding. I've never argued with the old saying that neutral should only be grounded once at the service entrance but ground can be attached to good quality grounds at many locations. (Never ground to a gas line.)

DISCLAIMER: I'm not legally qualified to give advise on this subject.

"I'm interested in why SolarEagle does not like water pipe grounding."

Many modern water installations use polyethylene pipe underground, with a coupling to copper pipe buried just below the surface at the building entry. Any attempt to "ground" to the copper will be fruitless and of high resistance, due to the short buried length of copper - perhaps less than one foot.

The polyethylene run saves the installer a few bucks and requires you to establish a different, proper ground connection.

If you suffer a fire and make an insurance claim, any evidence of non-code grounding is an immediate let-out for your insurer.

I would have to say that I have never seen an appliance where the chassis is connected to the neutral wire, and would question the sense and safety of such an arrangement - what happens if the neutral wire becomes open? The chassis then attains mains voltage and become a fatality in waiting, particularly as you mention the proximity of grounded water pipes.

Most regulators prohibit the separate connections of equipment to water piping for earthing purposes, generally due to the possibility of that piping subsequently being disconnected from the rest of the plumbing and the residual pipe and the appliance, then possibly being above earth potential if the appliance has some form of ground fault.

For those reasons, I would suggest that your option 1 is a no go.

Option 2 would be to certainly separate the jumper, as I said above, I would not have thought that to be an acceptable practice in the first instance.

For the reasons above, you should not be using the appliance if it is not properly protected against a chassis ground fault.

If you can't provide a correctly sourced earth, then consider installing an RVD (residual voltage device) adjacent to the appliance power outlet with a wire running from the earth pin on the outlet to the RVD earth connection, no physical connection to earth is then required thus eliminating the need for a separate connection to local water piping.

Here is a link to some relevant information if you are unfamiliar with RVD technology

The best ground should be at the main service panel.

Grounding elsewhere could create a rare, but potentially dangerous conflict of interest for the electrons should the ground resistance change and one of the "other" grounding locations becomes a "better" ground than what's at the main panel.

SE is correct. Do not use the water line for grounding. The electrical code doesn't allow this anymore because it is unreliable and you don't know the pipe is grounded or provides an adequate ground. The water pipe may present a long run to the grounding point for the pipe and if you are crawling around under the house and touch the pipe you may present a better ground than where the pipe is "grounded" and you, potentially, could electrocute yourself.

The point of contact between the ground and neutral wire is at the service entrance where you see neutral buss and service ground attached to each other. The idea is the grounded conductor (the neutral) and the grounding conductor (the physical ground wire) are kept separate thereafter. The grounding conductor is not supposed to carry current but is to provide safety to personnel if some equipment power finds it's way to the chassis.

Control equipment I've been involved with indicated a separate ground conductor to the service entrance and not to rely on conduit to serve a grounding function.

Also, I haven't checked out my dryer schematic but my recollection is that the three-prong dryer plug is 240 volt with the center/vertical prong being the ground(ing) conductor. The lower voltage for the dryer controls is developed via a transformer with a 240 volt primary.

Is your 3rd wire between panel & receptacle insulated? In order to create a 4 wire system, you need to connect that 3rd wire to your Neutral, for it to be a true 4 wire connection, which may require you to insulate it in the panel, and relocate it from the ground bar where it most likely is now.

I admit I was surprised when replacing range & oven here in NC in 1995 that the neutral & ground were bonded at the appliance, though all 3 wires were fully insulated back to the panel. Uncomfortable that there would be intentional current on the ground wire...

A good solid ground to a nearby receptacle sounds reasonable, from a pure engineering standpoint.

I have attached the relevant 2 pages extracted from the Owner's Manual (expected to be a .pdf but I guess only images allowed). Hopefully, one of you can steer me in the right direction (i.e. is there something I can do to reduce the chances of an inadvertent path for dangerous voltage or is this just something I must live with?). By the way, I should probably point out a few characteristics of my electric service: 1. I live in a condo and my interior breaker panel (actually considered a sub-panel, I believe) is fed from one of an external bank of 100-amp breakers. 2. I have no access to the ground conductor (nor to either of the two hot or neutral conductors). 3. The metal box enclosing my breaker panel appears to be grounded via the 1-1/4" rigid conduit stubbed up from the floor slab into the bottom of the breaker panel box.

The ground conductor people are talking about is inside the panel, it should be visible once the front cover is removed, main breaker off, of course. The other ground near the dryer is available inside the box for your washer 120v feed. You might need to install an old work box nearby to be able to fish a ground wire out of the 120v box to your dryer outlet box.

I not aware of the danger presented by the current method installed in hundreds of thousands of homes in the US, where the neutral is bonded to ground at the appliance, especially if no GFCI is installed at the panel.

I’d be interested in what changed in appliance construction to drive this change in wiring technique. I was surprised to learn that it was allowed in the first place, but it has been standard practice for decades.

"I not aware of the danger presented by the current method installed in hundreds of thousands of homes in the US, where the neutral is bonded to ground at the appliance, especially if no GFCI is installed at the panel".

In Australia (which are the only regulations that I am competent with), it has never been acceptable to bond the Earth conductor to the Neutral at any point other than at the main switchboard.

Doing so at the appliance introduces the possibility of the appliance chassis (and any other exposed metal attached to that earth wire) attaining mains potential in the event of the neutral wire becoming open circuit in concert with a high resistance or disconnected earth wire at any point up to reconnection to the neutral at the source, or its connection to the general mass of earth.

I was unaware of, and am really surprised that this system has been allowed to continue for so long in your country.

I suspect that part of the reason for the recent changes to this practice may be the probability of an RCD/GFCI falsely tripping due to the earth conductor carrying part of the return current that then bypasses the neutral terminal of the RCD/GFCI and thus presenting as a false ground fault.

Again, in Australia, all new installations, and most additions now require the installation of an RCD, so, if this is also the case in the U.S., it would appear to be necessary to cease the bonding practice in order to facilitate the correct functioning of the installed RCD.

So it looks like the 4 wire connection was introduced with the application of GFCI/RCD to these appliances. So if you don’t have a ground fault breaker feeding your appliance, there is not much benefit to a 4 wire system. An open neutral or ground wire AND an internal ground fault could electrify the appliance metal components. For appliances that have line to neutral components, usually controls, fan motors or dryer drum drive, an open ground will likely cause the appliance to be non-functional, at least alerting the user that something is wrong. Hopefully you don’t get a ground fault at the exact same time.

I've never seen nor heard of anybody being electrocuted by an electric dryer using the neutral as a ground for the cabinet....what are the odds? ...and when we start looking at odds that high I can think of other circumstances that are much more likely for electrocution...I would say if you're worried about it just make sure you are wearing rubber sole shoes when doing the laundry...

Any localities that apply NEC will require a ground run to a tested ground rod. The main panel ground lug is generally accepted by inspectors as a correct and suitable ground connection. The neutral wire commonly floats by a few volts from bonded ground.

I have yet to see a 3 wire run that was not hot 120vac plus side, hot 120vac minus side and ground. The wire you are missing is not ground, but is instead the power system neutral. It is likely that some components in the dryer run on 120vac and run power back through the neutral wire. It is non-code and typically prohibited to run operating power through the ground wire. The main issue is that if a ground wire connection fails at the wrong place that any items with a ground connection can become hot and pose an electrocution hazard. The other concern is that an electrician working on the circuit could disconnect a ground wire carrying current and wire will become hot and pose an electrocution hazard for the electrician.

Many national standards, and that in the UK is among them, prohibit the connection to a water pipe as a ground or earth return conductor. The reason is that many formerly-metal water distribution systems now have significant sections replaced with plastic water pipe, which does not offer the continuity to the star point of the local distribution transformer that is needed to provide a safe installation.

The consideration <...cost-prohibitive...> does not seem to take into account the <...cost...> of fatality if installation and maintenance is not done according to local national code.

If in doubt, consult a local qualified electrician.

Looking at what you wrote I can deduct that you are worried that the chassis of your appliance becomes Life if something goes wrong. If the piping system is not grounded properly, and you do not know if it is, your plan will under fault conditions also make every tap and every thing connected to the water system a death trap.

I will think that the wires in your appliance wall socket is L1, L2 and Earth (Ground) and not L1, L2 and Neutral as you suggest. The only way that the instalation could pass the code in any country.

...I will think that the wires in your appliance wall socket is L1, L2 and Earth (Ground) and not L1, L2 and Neutral as you suggest. The only way that the installation could pass the code in any country.

Here's a clipped image directly from the LG Owner's manual, showing one of the terminal points labeled "Neutral"...

But also note that Neutral and Ground is definitely not connected to each other.

The importance here is not what the cable are labeled in the drier. You have to find out what the input source for that point in the socket on the wall is. What does the house wiring bring to that point? On the diagram they call the white wire connected to ground just a "white harness wire" if it was indeed Neutral it will be called Neutral. We are here to try and assist you, not to argue with you. The earlier diagrams could not be read. The one you posted in your answer to me looks much better, thank you.

Dear Oomborrie,

I apologize if I came across as being argumentative. I only came here seeking some possible advice and direction. While I appreciate the outpouring of feedback from everyone, it hasn’t really given me the answer I’m seeking – namely: Is there anything I can (or should) do to enhance the safety of my dryer circuit. All I know is there must be a reason why 3-wire 2-pole dryer receptacles are no longer allowed by code for new construction. Maybe I’m being overly cautious and should just accept that there will “probably” never be a safety issue with my dryer. But without asking for (and comprehending) advice regarding the perceived problem, I can never know if there’s a solution (or if there’s one that is feasible). To further describe my scenario (and hopefully answer your specific questions) here is everything additional that I can think of as being relevant:

Four conductors enter my breaker panel enclosure through a rigid conduit, which is mechanically attached to the enclosure:

.....1 hot (black) to breaker rack lug

.....1 hot (red) to breaker rack lug

.....1 ground (bare) to grounding bar

.....1 neutral (white) to neutral bus (neutral bus has an integral tie strap, but the strap is NOT bonded to the metal box)

There is continuity between each of the following (verified with audible continuity checker)

.....Breaker Box to Neutral bus

.....Breaker Box to Grounding Bar

.....Breaker Box to Conduit

..........And by extension:

.....Neutral bus to Ground Bar

.....Neutral bus to Conduit

.....Ground Bar to Conduit

The NEMA 10-30 dryer receptacle is fed from a 2-pole 30-amp breaker via the three conductors (B, R, W) of a 10-Ga. NM-3 cable

The 3-wire dryer cord (NEMA 10-30P) has been wired as shown in the graphic in my previous post (i.e. Black, Red and White wires connected as directed). In addition, a bare copper wire was run between the grounding screw shown in the graphic (referred to as the “External Ground Wire”) to a grounding clamp attached to the iron pipe feeding the cold water angle stop for the washing machine.

The building has no crawl space and the water supply lines (iron pipe) are all underground and are most probably imbedded in the floor slab, so chances of inadvertent water pipe disconnection with subsequent contact with a worker is not likely.

In the remote electrical shed housing the 100-amp breaker feeding my breaker panel, there are few clues as to how my breaker (sub) panel is grounded, as everything is hidden inside enclosures and conduits. And in case it’s relevant, the 2-pole voltage is 208v not 240v.

p.s. The inability to attach a .pdf (or maybe there's a way that I overlooked), is why I posted the 2 pages as .jpg's. This was my first post that wasn't all text.

Can you do the readings not with continuity buzzer check but on the x1 Ohm scale and give us the Ohm reading. You have to know where that White wire in the wall socket come from. Red and Black comes from the Breaker. In the distribution board Neutral and Ground seems to be connected in your instalation. Also measure at the wall socket side at the drier the Ohm reading between White wire and the conduit. Buzzer will buzz, depending om the meter make up to 150 Ohms. We are working with Ohm readings smaller than that.

There have probably been many code changes that would differ from the existing structure, over time as things are changed out the standard procedure is to bring them up to code at that time...That might require rewiring the entire house depending on the year it was built..or just the circuit feeding the dryer...the changes are made over time to codes to enhance the safety of the occupants...My philosophy is if it ain't broke, don't fix it...If it's a source of worry for you, then change it out properly...I would think you have bigger things to worry about though...

I totally agree with you on this. You will see I am asking him about the distance and condition of the conduit. Next suggestion will be to use the wires to pull a draw wire back to the board and add an Earth wire to the wire loom.

What is the distance between Distribution Board and Drier Wall Socket. Is the wires in conduit for the total distance?

You are not likely to have a problem. I suspect the NFPA code changed because it became a possible safety issue. The neutral and ground are connected at your service panel. This is a requirement of the NFPA. White, or natural gray (whatever than may be) is the neutral, at least in the US, green or green with a yellow stripe or uninsulated bare copper, is the official color for the ground wire. I think in the past no-one thought it was a big deal to connect the equipment ground to the neutral but with the advent of ground-fault-circuit-interrupters it became necessary to separate the two. Also if the neutral became loose or broken the separate ground would protect a person who came in contact with the equipment if it was electrified. I'm surprised you said your power is 208V line-to-line instead of 240V. 208 V is indicative of a 3-phase 4-wire system which I wouldn't think would power a condo. Also, I suspect you pay a separate power bill which indicates you have separate metering. This would require you to a separate service entrance panel (which it sounds like you have) so the neutral buss is grounded at the panel.

Here is the info you need;

Also a link to the page for more details:

https://ask-the-electrician.com/wiring-a-range-power-cord.html

Direct your attention especially to the important notes