ptonsparky
Tom
- Occupation
- EC - retired
On service upgrades, are you required to install handle ties on breakers serving mwbc? Never entered my mind to do so until reading another thread on mwbc.
handle ties
- Thread starter ptonsparky
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I agree with Pete however you never know what the inspector will want.
210.4,B doesn't have an exception for existing stuff. And since you replaced the breaker, I imagine that's why the AHJ wants it handle tied (or a 2 pole).
Personnel safety
Also, just a Multi Wire Branch Circuit note - splice all neutrals with a wirenut, - not the screw terminal bus on the device. 300.13, B
Voltage unbalances
Personnel safety
Also, just a Multi Wire Branch Circuit note - splice all neutrals with a wirenut, - not the screw terminal bus on the device. 300.13, B
Voltage unbalances
- Location
- Simi Valley, CA
We require that you install the handle tie breakers for a service change.
Why wouldn't you put them in? Other than cost. Remember inspectors don't care about cost.
Why wouldn't you put them in? Other than cost. Remember inspectors don't care about cost.
To substantiate my stance on the OP's question I believe that requiring the handle ties or common trip breakers is retroactively enforcing the requirements of the NEC (given, of course, that the original MWBC was installed prior to the requirements of 210.4(B) and that the original installation had received approval).
If the AHJ's have determined that handle-tied or common-trip breakers are required for MWBC's that existed prior to 210.4(B) then I can't see how they can determine that AFCI breakers aren't required for the same service change.
Pete
shepelec
Senior Member
- Location
- Palmer, MA
How is requiring the new installation to conform with the current NEC retroactive?
If you are installing a new panel and breakers I would say it needs to conform to the current code.
Arc-faults may have a problem with the wiring configuration where as handle ties or two pole breaker would not.
If you are installing a new panel and breakers I would say it needs to conform to the current code.
Arc-faults may have a problem with the wiring configuration where as handle ties or two pole breaker would not.
If a new MWBC is installed then I would agree.
The question, as I understand it, is not whether a certain type of breaker would be problematic with existing wiring but whether a new or different type of breaker (i.e. AFCI or Handle-tie) can be required to be installed for existing circuits.
It is simply my opinion that it is not enforcable and would be retroactive.
Pete
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
I agree with this post.
Whether or not it is problematic with the exiting wiring shouldn't really have any bearing on NEC compliance.
- Location
- Simi Valley, CA
That was pretty much what I was gonna say.
I'm going to make you do the panel schedule per the new code, I'm going to make you update the grounding and bonding if it's required, I'm going to require that you put in the correct size riser and service entrance conductors. I don't think a couple of two pole breakers are really going to matter that much.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
You wouldn't require that for just a panel change would you? A service upgrade I can see, but not just a straight panel swap.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
I agree with these guys. And too add, requiring AFCI would also dictate that only a few certain type of panels could be used if there are existing MWBC because AFAIK only a few mfgs make 2pole AFCIs.
- Location
- Simi Valley, CA
Well let me just clarify due to regional differences. Here that's usually one in the same.
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