MWBC Question Again

Status
Not open for further replies.
kwired said:
Well no, but if using GE single pole AFCI's and possibly some others now, you can.
Click to expand...

But why would you wan to ?

To me, that just creates another avenue for breakers to trip in an already neusance trip ridden scenario.

JAP>
 
jap said:
But why would you wan to ?

To me, that just creates another avenue for breakers to trip in an already neusance trip ridden scenario.

JAP>
Click to expand...
GFCI receptacles on a MWBC isn't a problem, and I have done that for years. If using GFCI breaker - it will have to be a two or three pole GFCI breaker or you will have problems even with no active load if you tried to share a neutral.
 
kwired said:
GFCI receptacles on a MWBC isn't a problem, and I have done that for years. If using GFCI breaker - it will have to be a two or three pole GFCI breaker or you will have problems even with no active load if you tried to share a neutral.
Click to expand...

That's my whole point.

So what was the GE Breaker thing you were talking about earlier?

JAP>
 
jap said:
That's my whole point.

So what was the GE Breaker thing you were talking about earlier?

JAP>
Click to expand...
GE AFCI's (never used one but have read about them) supposedly don't have any GFP anymore and you can share load side neutral between them and another circuit. It is the 30 mA GFP in most other AFCI's that won't allow you to share neutral with any other loads period, as it is same thing as GFCI just with a higher trip setting. Some have mentioned that there are a few others out there like that now - I really don't know, thought Eaton's BR was supposed to be one, but ones I have seen recently didn't seem to indicate they were that way. Most other AFCI's I have been involved with were Square D, they definitely still have GFP function.
 
Spa Breakers are GFCI and are available with and without a load side neutral connection... the ones with a neutral are available up to 50 amps, ones without, 60 amps.

And I agree about the multiwire branch circuits with GFCI receptacles on them... The multiwire branch circuit is split into two standard branch circuits, at which point either one or both can have a GFCI receptacle, with no operational problems.
 
JFletcher said:
The multiwire branch circuit is split into two standard branch circuits, at which point either one or both can have a GFCI receptacle, with no operational problems.
Click to expand...

That's pretty common knowledge, and, most spa breakers are 2p and 240v loads.

We are discussing 1p Arc Fault or Ground Fault circuits originating at the breaker in the panel.


JAP>
 
jap said:
That's pretty common knowledge, and, most spa breakers are 2p and 240v loads.

We are discussing 1p Arc Fault or Ground Fault circuits originating at the breaker in the panel.


JAP>
Click to expand...
It is the GFP component of many AFCI's that will require neutral to return to the breaker itself, MWBC's will not work because of how these function unless the MWBC is supplied by a true 2 pole unit.

Newer GE AFCI's is one example where this no longer applies as they don't have a GFP component in them anymore.
 
When in the world will a neutral have full voltage on it?we do know what a neutral does right? It carries minimal potential yes not saying to go lick the neutral but ive never come accross a neutral with 120v coming back if u have then your doing something way wrong


Sent from my iPhone using Tapatalk
 
ActionDave said:
I think being forced to shut off three circuits instead of one makes it more likely someone will choose to work hot.

I also think MWBC will die off in my lifetime. They will either be made illegal or they will be not allowed by job specs.
Click to expand...


I rarely see MWBC being used now. I know a while back they were used a lot especially for lighting circuits.
 
AntTnson said:
When in the world will a neutral have full voltage on it?we do know what a neutral does right? It carries minimal potential yes not saying to go lick the neutral but ive never come accross a neutral with 120v coming back if u have then your doing something way wrong


Sent from my iPhone using Tapatalk
Click to expand...
In a two wire circuit it carries every bit of current the ungrounded conductor does. Disconnect it under load and touch it and you will be subject to full 120 or 277 volts of the supply circuit.

In a multiwire circuit it is carrying unbalance current from the associated ungrounded conductors. You still don't want to disconnect it while loaded and touch it, how much voltage it will have to ground depends on how balanced the loads are.
 
I've had a few bad experiences of disconnecting neutrals and finding they were live. More often from unintentional MWBCs, a.k.a. bad wiring, than from an intentional MWBC, but I've seen both and it amounts to much the same thing. Point being, yes, this is a real thing.

I just wish people would mark and group MWBCs, or only use them with cable. I don't need handle ties if that's done.
 
jaggedben said:
I've had a few bad experiences of disconnecting neutrals and finding they were live. More often from unintentional MWBCs, a.k.a. bad wiring, than from an intentional MWBC, but I've seen both and it amounts to much the same thing. Point being, yes, this is a real thing.

I just wish people would mark and group MWBCs, or only use them with cable. I don't need handle ties if that's done.
Click to expand...
Which has been a rule for a while now, unless you are still on what 2005 or earlier NEC?
 
kwired said:
Which has been a rule for a while now, unless you are still on what 2005 or earlier NEC?
Click to expand...

I know it's a rule. My complaint is people not following it. And I'm just saying it's a much more important rule than the handle-tie rule. For one thing, if there's multiple MWBCs in a single raceway, handle-ties don't tell you which neutral belongs to which hots.
 
jaggedben said:
I know it's a rule. My complaint is people not following it. And I'm just saying it's a much more important rule than the handle-tie rule. For one thing, if there's multiple MWBCs in a single raceway, handle-ties don't tell you which neutral belongs to which hots.
Click to expand...
Apparently your inspectors aren't enforcing it either, or just aren't paying close enough attention to catch it if they do know better.
 
Status
Not open for further replies.
Top