Wiring a clothes dryer

[JoeOef]

My wife and I just moved into our first home. As an older house that is mint, but has seen no upgrades, the wiring is one of our first major projects. The house came with many of the original 1948 appliances, including the dryer which was wired 3 wire 220. We will be running four wire service to the dryer next week, but in the mean time, the electrician advised me to hook up a female 4 wire plug (old dryer was hard wired in) to the existing wire, and running a separate, insulated ground to the water pipe next to the equipment, where another outlet is also grounded. I've done all this, and have a working dryer, but am paranoid about safety with an unconcerned, un-technical wife and two small kids running around. Am I ok doing it this way?

On a side note, the electrician also told me by grounding to a cold water pipe, I could potentially electrify all the water in my house and "kill everybody" ( his words) and to be careful. Any truth to this? I read groubdibg to water pipes was at least at one time to code. I'm thinking about getting a different electrician or wiring new 3 wire service to the rest of the house myself.

 

[Socophreak]

You need to ensure your pipes are bonded to ground. Just bonding a circuit ground to the water pipes is not good enough.

I would just run a 4 wire circuit all the way back to the panel. W/ new outlet. This may not be the easiest way, but it is certainly the safest.

 

[wyliesdiesels]

To prevent electricity from flowing on the grounded metal in your house, the water pipes need to be bonded to the main service panel AND the neutral to ground bond connection in the back of the dryer where the cord connects needs to be disconnected! If left bonded and the neutral connection drops out, then yes, u can have a shock potential! Grounded water pipes dont create shock potential, its the bonding in the dryer that does!

If your 3-wire dryer feed connects to the main service panel, then it is 'grandfathered' in. If the 3-wire feed instead connects to a subpanel, this is a no-no amd needs to be fixed! I'm guessing it connects to the main service panel!

And u cant run any new 3-wire feeds for dryers and b upto code!

 

[JoeOef]

It does connect to the main service panel. I'm guessing its still advisable to upgrade to 4 wire? In the mean time, should I disconnect the ground?

 

[wyliesdiesels]

It does connect to the main service panel. I'm guessing its still advisable to upgrade to 4 wire? In the mean time, should I disconnect the ground?

Reread my comment(#3). I was editing as you posted! The neutral bonding in the dryer is the key! If u want to keep the ground wire hooked up, then remove the bonding strap. If u remove the ground wire, then leave the boding strip bonded!

 

[Charles (in GA)]

Dryers have operated for years on three wire systems, they work just fine that way. In many cases, there is a jumper inside the dryer terminal block access, that is removed or installed, depending on whether if it three or four wire, the instructions will tell you. Mine is running right now on a three wire system and there is no reason to go changing it right now. Wire it up per the instructions with the dryer for three wire and use it.

Charles

 

[JoeOef]

Washer/dryer are newish but were purchased used. I opened the breaker for the night and will download the instructions and figure out this bonding strap situation after work tomorrow. Thanks!

 

[wyliesdiesels]

Its real easy. U remove the cover where the cord connects to the dryer and there should be a bonding strap in there on the middle/neutral terminal.

 

[wssix99]

I've done all this, and have a working dryer, but am paranoid about safety with an unconcerned, un-technical wife and two small kids running around. Am I ok doing it this way?

It would probably be good to make sure the pipes are properly grounded and you should be all set.

Even with three wires of the four hooked up, I'd think you are probably just as safe as you were with the old dryer.

You can always remind your wife in the meantime (while you get the upgraded wiring run) we always choose to use the old stand-by option:

On a side note, the electrician also told me by grounding to a cold water pipe, I could potentially electrify all the water in my house and "kill everybody" ( his words) and to be careful.

If you hook up the wrong wire and connect a power wire instead of a ground wire - or have crossed wires in your dryer or outlet, this could happen.

 

[JoeOef]

To clarify though, and forgive my limited understanding, if the pipes are grounded properly, and the wires are connected correctly, if something shorts put and the ground acts like the safety it is supposed to, will it electrify the water in our pipes?

 

[sands35]

Electricity will take the shortest / easiest path. It will ground to well, the ground. There shouldn't (in theory) be enough potential between your faucet and your feet to create a problem. Besides, the breaker would have tripped by then anyway.

 

[wyliesdiesels]

To clarify though, and forgive my limited understanding, if the pipes are grounded properly, and the wires are connected correctly, if something shorts put and the ground acts like the safety it is supposed to, will it electrify the water in our pipes?

If a hot wire shorts to a grounded object such as a grounded water pipe, grounded appliance frame, etc. then the breaker SHOULD trip(Zinsco and Federal pacific Electric excluded). The grounded object therefore will only be electrified for a split second until the breaker opens(we're talking milliseconds).

To answer your question, if your water pipes are grounded to the main service panel correctly, then there wouldnt be a way for you to get shocked, through say electrified water, because the pipe IS the shortest, easiest return path via the ground bonding at the main panel.

The only way someone can get shocked is if they 'insert' themselves in between the circuit, such as one hand holding a live wire and the other hand grasping a grounded water pipe. Ive touched bare live wires a few times in my career(didnt know they were live at the time) and I didn't get shocked. How, u ask. Because there was no path for the electricity to return on; ground or neutral(my boots are electrically insulated and i follow the electricians rule of left hand behind my back, so my other hand wasnt touching an electrical path). Keep in mind that electricity is always trying to return to its source(eg. a transformer).

Electricity will take the shortest / easiest path. It will ground to well, the ground. There shouldn't (in theory) be enough potential between your faucet and your feet to create a problem. Besides, the breaker would have tripped by then anyway.

If by ground u mean the earth, then that would be incorrect. Electricity is always trying to return to its source and will flow on EGCs because EGCs are bonded to neutral in the main service panel.

 

[VHF]

I'm surprised more people weren't getting shocked by dryers with a 3-wire connection, especially in old houses with the dryer in a damp basement. The heating element is 240V, but the motor is only 120V, so the dryer does present an unbalanced load with some current on the neutral. With a 3-wire connecton, the neutral and ground are combined, and the dryer cabinent is bonded to this neutral. Because there is some resistance in the neutral wire, and there is current flowing on the neutral, the dryer cabinet won't be at quite the same ground potential as the neutral/ground buss in the main panel.

Imagine standing on a wet concrete floor in an old house with marginal wiring. Do you really want to touch that metal dryer cabinet? What if you are a better current path than the neutral wire back to the panel?

There's a lot of things I don't like in the NEC, but the 1996 change to require 4-wire circuits for dryers & stoves was a smart move!

I would use the temporary ground to a water pipe that the OP has done until a 4-wire circuit can be installed. As was already discussed, it is very important that the bonding jumper on the back of the dryer be removed (otherwise the water piping could carry neutral current.) It is also important to verify the water pipe in use has a continous metalic path back to the house's incoming water pipe (which is an excellent ground as you have many feet of metal pipe buried in the earth.)

 

[sands35]

If by ground u mean the earth, then that would be incorrect. Electricity is always trying to return to its source and will flow on EGCs because EGCs are bonded to neutral in the main service panel.

Yes, you are technically correct assuming house wiring is working, but that's not the OP's question (as I read it) and given his prior posts.

"Return to it's source" isn't quite correct though. Electricity will try and reach the lowest energy state possible. It will go from high potential to low potential and the low potential doesn't have to be at the source.

How I read his question:
Dryer shorts to ground, doesn't trip breaker (for some reason), and he is at the wash sink with the water running and his hands are in it (implied) and he has grounded the electrical panel to the water pipe in the house (prior posts from OP).... then his Q.

To clarify though, and forgive my limited understanding, if the pipes are grounded properly, and the wires are connected correctly, if something shorts put and the ground acts like the safety it is supposed to, will it electrify the water in our pipes?

Electricity will take the shortest / easiest path. It will ground to well, the ground. There shouldn't (in theory) be enough potential between your faucet and your feet to create a problem. Besides, the breaker would have tripped by then anyway.

So, no the water won't be electrified because there isn't enough potential between the water, the pipes and the ground (that you are standing on) to electrocute you.

 

[Milton Shaw]

My neighbors house (6 years old) has all PEX piping in the house. There is a #4 ground wire run from breaker box to the pressure regulator that is hooked to PEX on both sides of it. Lots of good that ground wire is doing. Of course this is the house the plumber got the blueprint turned around on and ran the icemaker water supply line to the middle of the living room floor. That did require a lot of stud cuts as all the water was in the wrong place coming out of the slab.