Inspector and MWBC

[curt swartz]

It may not be relevant to you but it is to me!
How would you do this with NM cable or MC cable I never seen 12/14/ w 12 G cable.

Why would you need a cable that has #12's and #14's? There is no issue using #12's on a 15 amp circuit.

 

[480sparky]

It may not be relevant to you but it is to me!
How would you do this with NM cable or MC cable I never seen 12/14/ w 12 G cable.

Click here.

 

[david]

.
The MWBC is question has one receptacle on a 15 amp and the other is 20 amp.
So, we have 15 and 20 amp breakers tied together with proper handle tie.
Neutral is #12, then the #14 and #12 on the breakers.

Click here.

How is that the same as having a MWBC originating from the distribution panel with #14 and #12 on the breakers at the panel and using one neutral to make up the MWBC.

If this is done using NM cable I do not see how this is being done.

If this is being done with 12/2 NM-B and 14/2 NM-B why not just land the #14 AWG neutral and the #12 AWG neutral.

If they are already that way then this is not a MWBC just because the breakers have a handle tie to disconnect them as one.

 

[Ponchik]

How is that the same as having a MWBC originating from the distribution panel with #14 and #12 on the breakers at the panel and using one neutral to make up the MWBC.

If this is done using NM cable I do not see how this is being done.

If this is being done with 12/2 NM-B and 14/2 NM-B why not just land the #14 AWG neutral and the #12 AWG neutral.

If they are already that way then this is not a MWBC just because the breakers have a handle tie to disconnect them as one.

OP said it was a MWBC.

 

[kwired]

How is that the same as having a MWBC originating from the distribution panel with #14 and #12 on the breakers at the panel and using one neutral to make up the MWBC.

If this is done using NM cable I do not see how this is being done.

If this is being done with 12/2 NM-B and 14/2 NM-B why not just land the #14 AWG neutral and the #12 AWG neutral.

If they are already that way then this is not a MWBC just because the breakers have a handle tie to disconnect them as one.

OP never specified what wiring method was used. We kind of have to assume it was a raceway though, as finding that combination of conductors in a cable would not be common at all. As has been mentioned one could special order it, but unless you had a need for a lot of it, wouldn't be worth the cost.

 

[480sparky]

How is that the same as having a MWBC originating from the distribution panel with #14 and #12 on the breakers at the panel and using one neutral to make up the MWBC.

If this is done using NM cable I do not see how this is being done.

If this is being done with 12/2 NM-B and 14/2 NM-B why not just land the #14 AWG neutral and the #12 AWG neutral.

If they are already that way then this is not a MWBC just because the breakers have a handle tie to disconnect them as one.

Try reading the entire thread now.

 

[Dennis Alwon]

David, in certain cities in the US you cannot use nm for homes. Chicago , I believe requires conduit so perhaps the op is from there. I guess the contractor felt if he installed a 12 on a 15 amp breaker that the inspector would give him grief. Who knows. Also some cities , like NYC, used to req. a minimum of #12

 

[david]

Try reading the entire thread now.

David, in certain cities in the US you cannot use nm for homes. Chicago , I believe requires conduit so perhaps the op is from there. I guess the contractor felt if he installed a 12 on a 15 amp breaker that the inspector would give him grief. Who knows. Also some cities , like NYC, used to req. a minimum of #12

I have read the entire thread; nothing that I posted would have suggested that I haven?t. The type of wiring method would have no relevance to the overcurrent protecting the conductors in question.
However the OP said that this was a service upgrade. That implies that the electrician demoed what was there and re-landed the conductors to the breakers.

What was presented in the thread was unique and I would guess few at most likely none of the members here has ever seen this done. That in its self would merit probing into the subject further.
The possibilities are it?s a raceway system feeding the receptacles? in the bonus room if so then all is well. However if it is not then something is amiss and the probing may result in that being corrected

 

[jeff48356]

The inspector may say No, but must quote a Code section to support the alleged violation.... not a 'shirt-pocket rule'.

Actually, city electrical inspectors can (and usually do) go above the NEC for their standards. It may not be an NEC violation, but may not be allowed in that particular city. I would agree with the inspector, and I would have never wired an MWBC with different sizes of wire/breakers in the first place. It just doesn't seem practical or the professional thing to do. If I needed two circuits of different amperages, I would have simply run them separately.

 

[John120/240]

Actually, city electrical inspectors can (and usually do) go above the NEC for their standards. It may not be an NEC violation, but may not be allowed in that particular city. I would agree with the inspector, and I would have never wired an MWBC with different sizes of wire/breakers in the first place. It just doesn't seem practical or the professional thing to do. If I needed two circuits of different amperages, I would have simply run them separately.

I agree 100%. However if you are in a predicament a 12-3 w/ground romex would be acceptable with a 20A on one leg & a 15A on the other leg with handle ties. Confusing YES, smart thing to do probably not.

 

[roger]

Actually, city electrical inspectors can (and usually do) go above the NEC for their standards. It may not be an NEC violation, but may not be allowed in that particular city.

Then it better be in a formal amendment that all the contractors have access to. If an inspector is making up his own rules as he goes along he should be challenged.

Do you think a cop that may think 55 MPH is to high of a speed limit has the right or leverage to to start enforcing his own speed limit?


Roger

 

[PetrosA]

I don't see any safety issues with this. As my own boss, I wouldn't wire something this way, but as an employee I can see where the need might arise depending on who you work for. That being said, I've seen similar situations where someone has tapped off of a 12/2 with 14/2 downstream, and not changed the breaker. If I'm working on a panel like this, I mark that 12 with "15A MAX Fuse" or something similar in the panel and change the breaker. If the OP's situation had the 15A and 20A breakers next to each other with a proper handle tie, I don't see any problem unless there is some specific local ordinance which forbids it.

 

[kwired]

Actually, city electrical inspectors can (and usually do) go above the NEC for their standards. It may not be an NEC violation, but may not be allowed in that particular city. I would agree with the inspector, and I would have never wired an MWBC with different sizes of wire/breakers in the first place. It just doesn't seem practical or the professional thing to do. If I needed two circuits of different amperages, I would have simply run them separately.

Why do you think meeting the requirements of NEC is impractical or unprofessional? Just because you never seen something before doesn't necessarily make it wrong. Nothing has created any additional hazards here, confusion to future installers or maintenance, maybe, but I call that incompetence and not a safety hazard.

Then it better be in a formal amendment that all the contractors have access to. If an inspector is making up his own rules as he goes along he should be challenged.

Do you think a cop that may think 55 MPH is to high of a speed limit has the right or leverage to to start enforcing his own speed limit?


Roger

:thumbsup::thumbsup:

 

[mwm1752]

Why do you think meeting the requirements of NEC is impractical or unprofessional? Just because you never seen something before doesn't necessarily make it wrong. Nothing has created any additional hazards here, confusion to future installers or maintenance, maybe, but I call that incompetence and not a safety hazard.

:thumbsup::thumbsup:

Incompetence seems to be an unprofessional practice IMO. That said no code violation per the NEC. Could you run a 12# cu & a 10# al with a 12# cu grounded conductor for your MWBC?

 

[kwired]

Incompetence seems to be an unprofessional practice IMO. That said no code violation per the NEC. Could you run a 12# cu & a 10# al with a 12# cu grounded conductor for your MWBC?

As long as the overcurrent device is 20 amp or less, or you have a condition like a motor circuit that would allow it to be larger, why not?

 

[Little Bill]

Contractor friend asked me if I had any input on the situation.
Inspector did not give Article but failed inspection until correction is done.
I have no idea.

There is a MWBC to separate receptacles.
Room with MWBC is merely a bonus room, so no particular need on amperage.
Older home getting a service upgrade.
The MWBC is question has one receptacle on a 15 amp and the other is 20 amp.
So, we have 15 and 20 amp breakers tied together with proper handle tie.
Neutral is #12, then the #14 and #12 on the breakers.
Inspector says "no", the #14 must be changed to #12 and both breakers must be 20 amp.

He did not leave any additional information as yet.

Thought would post and see if anyone had any ideas before he confronts the inspector, as we cannot find anything stating they must be the same, as long as the neutral is equal to the highest amperage breaker.

Ideas?

Thanks

If the guy doesn't want to challenge the inspector on changing the #14 to #12, then just change the 20A breaker to 15A.
Problem solved!

Then after inspection, change the breaker back to 20A,
Nothing violating the NEC either way!:thumbsup:

 

[iwire]

. Could you run a 12# cu & a 10# al with a 12# cu grounded conductor for your MWBC?

Sure, and I would if there was a reason too.