I have an older 220v wire with only 3 wires... 2 hot and 1 ground/neutral (bare). I need to connect (splice) it to a newer 220v wire with 4 wires... 2 hot, 1 neutral (white), and a ground (bare).

And older I mean less than 15 years old.

So what kind of cables do you have? Probably the old one is BX, with the metal outer sheathing. If this is the case, the metal sheathing is the "fourth" wire, serving as the equipment ground. The new cable is probably Romex, with the bare equipment ground.

You must use a metal junction box, you need to use an approved connector for the BX cable, and wrench tight the locknut onto the box. The bare wire from the other cable can be connected to the metal box using a machine screw into a threaded hole you will find in the back of the box. This is an approved method to connect the two equipment grounds from each cable together.

Do not forget to install a box cover once you are done splicing.

TK,

Are you sire he isn't referring to an appliance cord (e.g. a three-wire dryer cable that he is trying to tie into a four-wire line)?

Either way, it doesn't sound to me like his "older" cable is BX - he says "I have an older 220v wire with only 3 wires... 2 hot and 1 ground/neutral (bare)" - so he's obviously seeing a bare wire somewhere, not BX armor...

Cheers,
Moishe

I see your point, I did not pick up that the cable being referred to is SEU cable, two insulated hot wires, with the bare wrapped around the outside of the hots.

Got in late after a long day of electrical work. Sometimes the brain does bnot jive with the eyes.

In this case the 3 wire cable should be replaced with 4 wire, to extend the equipment ground back to the panel. This is probably for a dryer or a range, which now require 4 wire, and there is no other alternative to connecting the ground.

Good catch.

Thanks for the info... I did replace the old wire with a new 4-wire... 75ft of wire. Boy that wire has a mind of its own.

It was for a range. I'm now looking at moving a dryer... hope I don't find the same situation.

I am also facing this dillemna - connecting an old 3-wire 220, extending it with a 4-wire. The solution given me by an experience electrician is simply to ground the new green wire to a copper plumbing pipe near the junction box and run the new 4 wire 220 cable back to the panel.

Well, Bob, your "experience electrician" is a hack. It has been MANY years since it was legal (or safe) to ground to a local water pipe. They realize how dangerous this could be and dropped that allowance. This is especially true with the boom of Pex and cpvc piping being used.

I am confused, you say you are extending the old three wire cable, yet you say you will run the four wire cable back to the panel.
WHAT exactly are you doing?

I can say with certainty. You CANNOT extend an old 3-wire range circuit. Period.
You MUST run a new 4-wire circuit back to the panel.

Stan, thanks for your reply. The situation is an old home built probably in the late 40's or 50s. The kitchen is being remodeled, all the sheetrock removed making it possible to strip out all of the asbestos insulated wire, replacing it with Romex. None of the original circuits will be used. They will be disconnected and capped at the panel. This is where the old 3-wire 220 comes in. It serviced the original electric range but now a gas range will be installed. The breaker panel is an old pushbutton type and unfortunately located at the far end of the home in the basement where it would be impossible to run a new 4-wire cable without a lot of tearout. Plan is to junction that old 220 with a 4-wire cable and run it to a new subpanel in the kitchen which would service new circuits throughout the kitchen. The new 4-wire cable would be grounded to a copper pipe. The original breaker panel is grounded to the pipe where it comes into the house, rather than spikes driven into the dirt, as seems to be the practice now. The electrician in question has 50 years experience, has taught IBEW courses, has owned his company since the 50s and is up on the '08 codes. He knows this isn't exactly legal but doable in light of the situation and budget.

Knowing what type of cable they used back then it is HIGHLY likely this would not be a legal or safe thing to do. You DO need a 4-wire feeder to a sub-panel.



NO, it should not! From a legal and safety standpoint.
As I said, this was legal back in 1975, but they soon realized how dangerous this could be.
The piping in a house SHOULD NOT be used as an equipment grounding conductor.
The ONLY time this is safe is IF: a) the water pipe in question is being used as a grounding electrode, and b) you connect your ground within 5' of where the pipe enters the house.
Tell you electrician friend to look up 215.6 Feeder Conductor Grounding Means, 250.134 and 250.130(C).



The practice of using a metallic water pipe as the primary electrode has been around for many years. Newer codes require a supplemental electrode (or two) be installed as well.



Sometimes some of the old timers make the worst mistakes.
"Doable"?? Budget?? I hate being so harsh, but if your guy would do this he truly is a fool and doesn't value his reputation or your lives very much.

Please have him read those sections I mentioned to show how this is not so "doable".

HI guys,

T Steven's did you bother to check for the amperage needed by the new equipment? Were the amperage levels the same?

I did check the amperage of the new range and it was similar to the old. I ended up replacing the 3-wire with 4-wire... and feel much better about it than some make-shift splice.

"The ONLY time this is safe is IF: a) the water pipe in question is being used as a grounding electrode, and b) you connect your ground within 5' of where the pipe enters the house.
Tell you electrician friend to look up 215.6 Feeder Conductor Grounding Means, 250.134 and 250.130(C)."

Then I don't see the problem here really. Yes, the water pipe in question is in use as the grounding electrode for the main breaker panel. The primary ground is clamped to it immediately where it enters the house from the soil and has been probably since the house was built in the '40s. The new 4-wire cable ground for this subpanel will also be clamped to it within the 5' radius you outlined here. Seems as tho my electrician is thinking along the same lines as you. But he's also being pragmatic about ripping into finished areas just to tow the letter of the code. Afterall, people have lived in this house for decades with s water pipe ground. This guy can quote the code books too but also has the benefit of experience and knowledge born of decades in the field. Hardly a "hack" or a "fool."

See, now we are getting conflicting stories.

"The solution given me by an experience electrician is simply to ground the new green wire to a copper plumbing pipe near the junction box"

"The breaker panel is an old pushbutton type and unfortunately located at the far end of the home in the basement where it would be impossible to run a new 4-wire cable without a lot of tearout."

"The original breaker panel is grounded to the pipe where it comes into the house,"

Then you say:

"The new 4-wire cable ground for this subpanel will also be clamped to it within the 5' radius you outlined here."

If you can get the ground from the sub panel to the grounding electrode or grounding electrode conductor then why not run it to the panel? Or better yet run a new 4-wire cable?

The WHOLE point of this is NOT to "ground" the sub-panel to the actual earth. The point is to have a solid path to the main panel which is where you real safety "ground" comes from. This safety ground is created by the neutral to ground BOND in the main panel. A ground rod does nothing for safety as far as tripping breakers and short circuits are concerned.

If your last post is more accurate than the previous ones then yes, you are fine.


Oh, quoting code on the internet is easy if you know what you are doing. I assure you, my field experience is the reason I know what I am doing and the reason I know how to quote code.
So I ALSO have the "experience and knowledge born of (exactly two) decades in the field".

Stan, after reading your posts I don't think there's really any conflict here, maybe I could've communicated better. Wish I could show you the floor plan. To give you a better idea of what I'm looking at here - the old 220v wire comes all the way from the main breaker panel which is at the far end of the home to the area where I am remodeling. I wish to junction it and take it to a new subpanel via a new 4-wire cable where I can then run new circuits for the kitchen. The ground for this new cable would be clamped to the water pipe where it enters the house which is also right in the vicinity of both the junction box between the old 220 and the new cable, and also the new subpanel. As I 'd written before, this is also where the main breaker box is grounded with the copper water pipe where it enters the house. This ground wire runs all the way back to the main box. I realize that if there was a bigger budget the best solution would be to run a new 4-wire cable from this subpanel all the way back to the breaker box. This just isn't feasible but it looks as though we're still okay in light of these passages in the code. I guess my initial reason for posting was to get a second opinion. I sure found it! ;) Didn't mean to insult your experience - you wouldn't be the main answer man on this site if you didn't know your trade. Thanks very much for your input.