multi-wire branch circuits and AFCI breakers

[RustyShackleford]

I'm planning to replace the "fire-starter" Federal Pacific StabLok main load center in my stepson's house.

The house was mostly wired with multi-wire branch circuits (MWBC), that is, they used 12/3 and 14/3 cable in order to save a little copper. This means neutrals are shared between two hots (which hopefully are connected to opposite phases in the load center). They used single-pole breakers for the hots for the MWBCs. Do I understand correctly that this isn't kosher and that I should use double-pole breakers to land the two hots from each MWBC ? Or is there an option to tie together the handles on two single-pole breakers ?

If double-pole breakers are required, what if I want to add some AFCI circuits ? On a straight panel R&R like this, our AHJ does not require upgrading to AFCI; but I think it's a good idea for a few high-risk circuits, such as ones in sleeping areas and ones that tend to have a lot of extension cords plugged into them. But as far as I can tell, there's no such animal as a double-pole AFCI breaker. So what can I do ?

 

[Whitenuckler]

I'm planning to replace the "fire-starter" Federal Pacific StabLok main load center in my stepson's house.

The house was mostly wired with multi-wire branch circuits (MWBC), that is, they used 12/3 and 14/3 cable in order to save a little copper. This means neutrals are shared between two hots (which hopefully are connected to opposite phases in the load center). They used single-pole breakers for the hots for the MWBCs. Do I understand correctly that this isn't kosher and that I should use double-pole breakers to land the two hots from each MWBC ? Or is there an option to tie together the handles on two single-pole breakers ?

If double-pole breakers are required, what if I want to add some AFCI circuits ? On a straight panel R&R like this, our AHJ does not require upgrading to AFCI; but I think it's a good idea for a few high-risk circuits, such as ones in sleeping areas and ones that tend to have a lot of extension cords plugged into them. But as far as I can tell, there's no such animal as a double-pole AFCI breaker. So what can I do ?

Hi - I am not in your state, and not an electrician, however my first thought is that if the loads are 115V, and the breakers are side by side in the panel (or wired 230V) then it OK for single pole breakers. I'm not sure about adding single AFCI breakers ie if they would work properly sharing that neutral...should be OK. I believe you only buy 2 pole breakers or linkage tie's for 230V loads.
I will be interested in learning from this post. I added some heaters in my porch and used 14/3 and 2 SP breakers. Same as a kitchen plug I believe.

 

[RustyShackleford]

I'm not sure about adding single AFCI breakers ie if they would work properly sharing that neutral...

I'm planning to use Siemens, since that's what I'm familiar with. Their AFCI breakers only have the hot connection (the neutral can go straight to the neutral bar). So no issue there.

 

[Whitenuckler]

I'm planning to use Siemens, since that's what I'm familiar with. Their AFCI breakers only have the hot connection (the neutral can go straight to the neutral bar). So no issue there.

To be honest, I have only looked at what they call GFCI's which detect a possible leak of power from the hot. I have never installed one of these AFCI breakers in a panel myself. You are right, it sounds like they are only concerned with their hot circuit. I have not really looked at what they are for...arc's that are not high enough to trip the breaker on an overcurrent?

 

[EbS-P]

Handel ties existed for regular single pole breakers. I doubt they do for new afci beakers but they might. Why not just use double pole afci breakers?


Yes you need the handles tied in the mwbc. It’s still allowed in code (I think) so breakers must be available.


Your friend has shared a link to a Home Depot product they think you would be interested in seeing.

Siemens Type QAF 20 Amp Double-Pole Combination AFCI Circuit Breaker Q220AFCP - The Home Depot

Bring the best and essential upgrade to your electricals by selecting this Siemens Type QAF Pole Combination AFCI Circuit Breaker.

www.homedepot.com

 

[RustyShackleford]

Your friend has shared a link to a Home Depot product they think you would be interested in seeing.

Holy Mazola ... $122.

So if I decide to forgo upgrading any circuits to AFCI (or do it at the outlets), do I need to use ordinary double-pole breakers on the MWBC circuits, or can I just use single-pole ones with handle ties ?

 

[Whitenuckler]

Hi - I am not in your state, and not an electrician, however my first thought is that if the loads are 115V, and the breakers are side by side in the panel (or wired 230V) then it OK for single pole breakers. I'm not sure about adding single AFCI breakers ie if they would work properly sharing that neutral...should be OK. I believe you only buy 2 pole breakers or linkage tie's for 230V loads.
I will be interested in learning from this post. I added some heaters in my porch and used 14/3 and 2 SP breakers. Same as a kitchen plug I believe.

It looks like I was wrong. The handles need to be tied together, or a 2 pole breaker used for a plug. It is a safety issue as if one side of the plug is faulty, they want to isolate the entire plug as it is one unit.

 

[RustyShackleford]

It looks like I was wrong. The handles need to be tied together, or a 2 pole breaker used for a plug. It is a safety issue as if one side of the plug is faulty, they want to isolate the entire plug as it is one unit.

What you mean by a "plug", sorry I'm confused.

 

[RustyShackleford]

Anyhow, I'm getting the impression it's ok to use single-pole AFCI breakers (assuming they're the kind that don't have a neutral connection, the neutral just goes straight to the neutral busbar), and tie the handles. Sound right ?

 

[Whitenuckler]

What you mean by a "plug", sorry I'm confused.

Sorry I have a bad habit of calling wall receptacles plugs. A plug is wired to a a cord, and goes into a receptacle. I was down in the basement and put a tie between my two handles. I didn't have a code one yet but used a screw. I can see why they want that for a receptacle, however you are shutting off a side that could be fine.

 

[Whitenuckler]

Anyhow, I'm getting the impression it's ok to use single-pole AFCI breakers (assuming they're the kind that don't have a neutral connection, the neutral just goes straight to the neutral busbar), and tie the handles. Sound right ?

No, not if it feeds any receptacle. I'm not sure if the rule is just for receptacles. You could run 14/3 to a junction box and use one side for lights and one side for plugs. Is that the sort of circuits at the house?
I just came up with an example. A ceiling fan with fan and light wires. It is common to use 14/3 and two single pole breakers I believe.
Really, if you are feeding a cable with 230V, you should use 2 pole breakers as if you had a problem in your cable, would you really want power still feeding it? Probably not.

 

[EbS-P]

Search the Siemens catalog and see if they make what you need. How many circuits are you taking about? the extra cost is probably less than $1000. That may seem like a lot but it’s how they would do it if you paid someone.

I am all for saving money but if the correct product exists it’s what I’m using.

Be sure and save a double space at the top for whole house surge protection.

I’ve told my AFCi story before but here it is again. I had a dehumidifier that was recalled. Never had an issue with it for 4 or 5 years. But I read how many fires they started and went and got a replacement and just kept the recalled unit. New one died in less than a week. Returned it only for the store to be out. It was hot and humid so unplugged the recalled unit back in. I woke up to and APU On our TV beeping. “Weird” I thought. Remember it’s down the line from an AFCI receptacle I installed. Reset it. Was woken up an hour later by the beeping again. Then it hit the recalled dehumidifier. I went right then and cut the cord off the unit. Never has the AFCi tripped again.

I am a firm believer in AFCI everywhere it’s required by CURRENT code.

If the correct double pole with Handel tie exists use it. If your son is paying for the parts tell him it’s his Christmas present.