I hope I don't get run out of Dodge by bringing up multiwire circuits (I still tend to call them Edison circuits even though the configuration, I believe, was intended for DC as Edison HATED AC as most folks know).

Anyway, I have two pairs of existing Edison circuits (four circuits total) that I do not intend to completely re-wire since they work just fine. However, one of these pairs feed the outlets in my kitchen which I would like to GFCI-protect; the second pair feeds the clothes washer and a freezer outlet which I'm debating about GFCI retrofitting.

My questions are:

1) I intend to use two-pole GFCI breakers to accomplish this- are they prone to nuisance tripping in this type of setup?

2) I heard somewhere that GFCI outlets can be used on these IF they are installed at the end of the circuit run(s); is this true?

Yes, multiwire or Edison circuits are like oysters, we either seem to love them or hate them (my brother despises them something fierce but I don't mind them myself); nonetheless, they do have their place. I do not intend to start a debate (war??) on this configuration but merely have some questions on GFCI protection on these types of circuits.

Thank you in advance.

You can install GFCI receptacles on any section of a multiwire circuit, but cannot use the feed through option.
Your multiwire circuit's grounded conductor should be pigtailed at each outlet any way.
Just install the GFCI receptacles individually.
You will need a separate GFCI receptacle for each location...S

You can protect both circuits on the multiwire by putting a GFCI outlet at the first outlet on each line after the circuit splits.

I think what I'll do is put a two-pole GFCI on the kitchen circuits and use solo GFCI outlet(s) on the other two circuits if/when I feel the need for them.

quote:

You can protect both circuits on the multiwire by putting a GFCI outlet at the first outlet on each line after the circuit splits.

I've heard that GFCI outlets do NOT like this on a multiwire configuration... I think electure's point on not using the feedthroughs may be the correct one... I just want to be sure. Maybe I didn't understand the comment correctly???


quote:

Your multiwire circuit's grounded conductor should be pigtailed at each outlet any way.

Indeed. You folks would not believe what I found when I bought this house (well, actually, maybe you would). Someone decided to use the backwire and sidewire slots on the duplex receptacle feeding the clothes washer to split up the circuits!!!!! If this was ever legal, I don't believe it ever should have been. If the device fails, subsequently opening up the neutral, well, you know... WOW! That washer NEVER spun those clothes so dry before Needless to say, I ripped it out and done it up right.

UTMOST CARE must be taken to ensure neutral integrity on multiwire circuits.

Again, I must thank the host(s) for this fantastic website, and thanks to all of you for your expert advice on matters such as this.




[This message has been edited by Sir Arcsalot (edited 03-14-2004).]

I would agree with Eelctric Eagle on his response.

Remeber that A GFCI compares the difference between the ungrounded and grounded conductors downstream of the device, not upstream. The GFCI is blind about what is occuring before the device. As long each circuit has its own nuetral after the GFCI you should be OK.

I have installed GFCI on Shared neutral circuits but it kept triping. So i had to pull in an additional neutral.(flex job)
It was very strange to me because a GFCI does not see anyhting upstream from it. But it kept triping. I know there wasn't anyhting on the load side connected.


Edward

Edward, I must ask, what did you mean by
Roger

Ed there must have been something else going on.

The feed to any panel is essentially a multiwire circuit and GFCIs work down stream from there

What i meant was that the job was not romex. So i did not run just a grounded(neutral) wire through the studs. I ran an additional neutral through the flex.

I am not sure if there was anything else going on, because as soon as i connected the additional neutral all was working fine.

Edward

Must have hooked them up backwards!

I reckon it wouldn't hurt to mention some history of this thing on my behalf.

Once I discovered the spaghetti-bowl-in-a-handy-box fiasco, I went to shut off the breaker to the clothes washer. I then checked the voltage with my trusty digital VOM- 15 volts... HMMMM... my thoughts were a possible failing breaker or (perhaps) a minor carbon track somewhere within it, or something. Upon further investigation I found a second outlet not too far away and it appeared to be wired to this same circuit. Checked the voltage- 120. It was only then that I realized the circuit was Edisoned. Found the other breaker three-up from the washer circuit, on the opposite leg, shut it off, checked the voltage- zero volts; a little bit safer to work on.

My thinking about this was that, if this "back EMF" from the opposite leg was somehow "seen" by the GFCI outlet it would cause nuisance tripping but for some reason it would work fine at the end of the circuit run (perhaps) because nothing was downstream of it, somehow upsetting the circuit balance (in retrospect, it appears that my logic has some holes in it. Even so, theory and practice are oftentimes different worlds).

Even if the GFCI outlets do work fine at the beginning of the circuit and using the feedthroughs were no problem, this (in my opinion) should never be done as the integrity of the neutral grounded conductor should be totally device-independent on multiwire circuits. Pigtails prevails... Just my opinion...


[This message has been edited by Sir Arcsalot (edited 03-15-2004).]

[This message has been edited by Sir Arcsalot (edited 03-15-2004).]

This reading was nothing to worry about, a digital VOM reads induction from the other circuit, try the same measurement with analog meter.

I run many multiwire branch circuits and as long as you follow the rules that apply to them they work great, how many service entrance neutrals do you have?

GFCIs do work down line from a multiwire branch circuit, not some times, every time.

Compare a GFCI fed from a multiwire branch circuit to a GFCI fed from a 2 wire branch circuit.

Once you get back to the panel it is the same thing, a common neutral.

One thing you can not do is protect outlets down line on a multiwire branch circuit with a GFCI outlet.

This is what electure and Electric Eagle where saying.


[This message has been edited by iwire (edited 03-16-2004).]

Sometime last evening I thought about induced voltage being the likely source. Yesterday it seemed as though my brain spent a few hours in a paint shaker.

Thanks a great big bunch to all of you for your insight and expert advice on this matter; I think my light bulb is fully socketed now.

I have another, semi-unrelated question that I can't find the info for on this board: how do you box in the quotes with those lines? I don't know how to make the lines appear, though it's probably very simple.

[This message has been edited by Sir Arcsalot (edited 03-16-2004).]

When you click on "reply" you get the screen I am writing in now. To my left is a link labeled "*UBB Code is ON". Click on this link to see the rules.

Earl

You can also click on edit for any post that has the effect that you are trying to duplicate and you will see the UBB code. You can't edit any posts except your own, but you can see the code.
Don