# MWBC Pump and Alarm Sewer



## Dennis Alwon (May 9, 2009)

IMO both hookups are noncompliant. I wrote a proposal to get this changed.

If you use a mwbc then a dp breaker or sp breakers with ties is required and this would effective kill the alarm circuit in case of a short.

Two circuits to a separate structure violated 225.30. IMO I would violate this rule not the other.


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## Cletis (Aug 20, 2010)

*passes*

Hopefully, you submit and it passes. BTW, it already has been amended locally in multiple state sewer sites i've been surfing last night all over the nation.


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## electricmanscott (Feb 11, 2010)

Dennis Alwon said:


> IMO both hookups are noncompliant. I wrote a proposal to get this changed.
> 
> If you use a mwbc then a dp breaker or sp breakers with ties is required and this would effective kill the alarm circuit in case of a short.


Is that an electrical safety issue that the NEC would/should have any interest in?


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## Dennis Alwon (May 9, 2009)

electricmanscott said:


> Is that an electrical safety issue that the NEC would/should have any interest in?


Not all codes are necessarily a safety issue however, I think using a MWBC with handle ties or a dp breaker can be a health issue if the pump fails and sewer backs up in the house. 

I do not understand why 2 circuits are not allowed to be brought to another structure-- it is allowed in some cases so I don't know why the code mandates that. 

I do feel it is worth fixing loopholes so that inspectors can make a realistic call. If there is an exception than there is no issue.

We have one jurisdiction that will not allow the MWBC and , in fact, got the manufacturer to change their connection so that 2 circuits can be used. Of course, that is the other issue that they have not bothered to enforce.


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## electricmanscott (Feb 11, 2010)

Dennis Alwon said:


> Not all codes are necessarily a safety issue however, I think using a MWBC with handle ties or a dp breaker can be a health issue if the pump fails and sewer backs up in the house.



True enough, but you submitted a proposal to the NEC which is not a design manual, unless of course you have some deep pockets and lobbyists, then it is whatever you want it to be. 


But anyway, regarding your proposal,
What does this have to do with the NEC? Seems that it would be out of the scope of it, that's all I'm getting at.


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## Dennis Alwon (May 9, 2009)

electricmanscott said:


> True enough, but you submitted a proposal to the NEC which is not a design manual, unless of course you have some deep pockets and lobbyists, then it is whatever you want it to be.
> 
> 
> But anyway, regarding your proposal,
> What does this have to do with the NEC? Seems that it would be out of the scope of it, that's all I'm getting at.



What is not in the cope of the NEC? The septic Pump? The NEC requires a MWBC to simultaneously disconnect both conductors. I wrote an exception to allow a septic pump to be exempt from having a dp breaker or handle ties.

I wrote another proposal to allow 2 circuits to one structure specifically for septic pumps.

I am confused as to why you think this has nothing to do with the NEC. It has everything to do with it, IMO.


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## cultch (Aug 2, 2011)

I can't let my pride get in the way of this one. I searched the net and could not find an answer.

What is MWBC??? A disconnect??? Wire??? What? Maybe we call it something else but I am not familiar with the term.


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## oldtimer (Jun 10, 2010)

cultch said:


> I can't let my pride get in the way of this one. I searched the net and could not find an answer.
> 
> What is MWBC??? A disconnect??? Wire??? What? Maybe we call it something else but I am not familiar with the term.



Multi-Wire-Branch-Circuit.


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## electricmanscott (Feb 11, 2010)

Dennis Alwon said:


> What is not in the cope of the NEC? The septic Pump? The NEC requires a MWBC to simultaneously disconnect both conductors. I wrote an exception to allow a septic pump to be exempt from having a dp breaker or handle ties.
> 
> I wrote another proposal to allow 2 circuits to one structure specifically for septic pumps.
> 
> I am confused as to why you think this has nothing to do with the NEC. It has everything to do with it, IMO.


Maybe I'm reading something wrong. Is the issue if the MWBC ocpd opens the alarm circuit will be killed too? If so, nothing to do with the NEC imo.

I like the idea of allowing more than one circuit to a "structure" (awfully defined by the NEC IMO) but I just don't see what the justification is.


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