Shared neutral on gfi

[Cjmcelectric]

If you have a shared neutral example : one hot feeds frig, one hot feed kitchen gfi. If you turn off gfi circuit to service it will that neutral have any current from frig and does this pose any hazard.does the neutral load off frig take any and all paths back to source equally? I'm assuming this is the purpose of multi-wire branch circuits are required to be simultaneous trip?thanks

 

[Dennis Alwon]

If you have a shared neutral example : one hot feeds frig, one hot feed kitchen gfi. If you turn off gfi circuit to service it will that neutral have any current from frig and does this pose any hazard.does the neutral load off frig take any and all paths back to source equally? I'm assuming this is the purpose of multi-wire branch circuits are required to be simultaneous trip?thanks

That is correct-- you do not want to disconnect one side of a multiwire branch circuit without disconnecting the other. Remember that electricity will take all paths back to the source including thru you.

 

[Cjmcelectric]

Thanks Dennis!

 

[John120/240]

Also if you just had two single pole breakers with no handle ties, (the old fashioned way) you can send 240 V to one of the outlets.

 

[kwired]

Lets look into this one step further - Say your installation is old enough that handle ties were not required then it is possible to turn off the portion feeding the GFCI receptacle. (The fact that it is a GFCI really means nothing to us for the question brought up, it can be supplying pretty much anything that operates at 120 volts) If your intention was to change the receptacle - the only problem would be if the MWBC neutral was not pigtailed then supplied the receptacle - which I believe it has been long required to not depend on the device as the sole neutral connection for MWBC's, as removing the device would open the neutral that may still be carrying current for the other portions of the MWBC.

There is similar rules requiring the EGC to not be opened when removing devices from the circuit so that continuity of the EGC is maintained.

 

[ActionDave]

That is correct-- you do not want to disconnect one side of a multiwire branch circuit without disconnecting the other. Remember that electricity will take all paths back to the source including thru you.

True sort of. Depending on where you are in the circuit there is no danger.

Also if you just had two single pole breakers with no handle ties, (the old fashioned way) you can send 240 V to one of the outlets.

Again true. But it won't happen if you know what you are doing.

How much I resent 210.4(B)? I would remove it from the code before I would get rid of AFCI's.

 

[kwired]

True sort of. Depending on where you are in the circuit there is no danger.

Again true. But it won't happen if you know what you are doing.

How much I resent 210.4(B)? I would remove it from the code before I would get rid of AFCI's.

You must not do a lot of dwelling unit work.

Or you do, and like the extra sales from selling and maybe troubleshooting AFCI's:happyyes:

 

[handy10]

Lets look into this one step further - Say your installation is old enough that handle ties were not required then it is possible to turn off the portion feeding the GFCI receptacle. (The fact that it is a GFCI really means nothing to us for the question brought up, it can be supplying pretty much anything that operates at 120 volts) If your intention was to change the receptacle - the only problem would be if the MWBC neutral was not pigtailed then supplied the receptacle - which I believe it has been long required to not depend on the device as the sole neutral connection for MWBC's, as removing the device would open the neutral that may still be carrying current for the other portions of the MWBC.

There is similar rules requiring the EGC to not be opened when removing devices from the circuit so that continuity of the EGC is maintained.

I don't believe it is possible to place a GFI receptacle in a MWBC without a pigtail to the neutral, at least not if current is being drawn by the other side of the circuit.

 

[ActionDave]

You must not do a lot of dwelling unit work.

You are correct but I do work on homes. That seems to be the dividing line between those who use MWBC and those that cringe in fear.

The funny thing is I started out roping houses and never knew a building that did not have a home run that was not a MWBC. 12-3\14-3 to the crawl, same to the attic, branch out from there

Or you do, and like the extra sales from selling and maybe troubleshooting AFCI's:happyyes:

AFCI's are a fraud. I have wired and seen circuits in homes that I know are clean and they trip. This became a bigger problem when the combo, series/parallel breakers came out. Nuff said. I won't go any further. That horse has be beat enough.

 

[Dennis Alwon]

The funny thing is I started out roping houses and never knew a building that did not have a home run that was not a MWBC. 12-3\14-3 to the crawl, same to the attic, branch out from there

You obviously never saw one of the homes I wired. I think in 30 years I may have used a multiwire branch circuit 2 or 3 times and it was for outdoor lighting.

 

[kwired]

I don't believe it is possible to place a GFI receptacle in a MWBC without a pigtail to the neutral, at least not if current is being drawn by the other side of the circuit.

Not possible or not code compliant?

 

[Sierrasparky]

Last time I checked the GFCI's have two holes for each connection. SO you can have a situation where the nuetral is broken by removing the outlet. Not code compliant but you will find it out there.