Twin breakers

[cppoly]

Are twin breakers (having two breakers installed where one breaker would normally occupy) in commercial or residential buildings code complaint?

 

[jaggedben]

Yes. If they are listed on the panel label to be installed in that panel (same as any other breaker).

 

[LarryFine]

Are twin breakers (having two breakers installed where one breaker would normally occupy) in commercial or residential buildings code complaint?

Yes, and we generally prefer to call them 'tandem' breakers.

 

[suemarkp]

In addition to being listed for the panel, the particular slot also needs to be rated for them. There are many panels rated as 30/40 -- 30 slots, 40 circuits. This provides 10 slots where tandem breakers can go and 20 where they cannot. I think this used to be because of the older limit of 42 overcurrent devices per panel and that limit has gone away. Now days you can find 30/60 and 40/80 panels where every slot can take a tandem.

Running out of neutral holes is also a problem in the older panels, even if you are legally using the slots.

 

[jap]

The "twins" or "tandems" or "piggybacks" whatever you want to call them aren't generally the problem.

It's the neutrals that are associated with the existing cicuits that are most times not given the attention they deserve when people go moving things around to install them.

JAP>

 

[LarryFine]

It's the neutrals that are associated with the existing cicuits that are most times not given the attention they deserve when people go moving things around to install them.

Agreed. You often find both legs of a MWBC put on the same phase.

I have seen new work with the black and red on the same tandem.

 

[infinity]

Are twin breakers (having two breakers installed where one breaker would normally occupy) in commercial or residential buildings code complaint?

Type of occupancy doesn't matter as long as the panel listing is followed. For something like a 40/80 that suremarkp mentioned you could have 40 tandems providing 80 circuits. If the panel were listed as 40/60 then only 20 tandems can be installed.

 

[Steviechia2]

The problem is most circuits now have to be arc faults so the days of tandem breakers are limited

 

[Crash117]

Siemens is making tandem arc fault where the neutral does not connect directly through the breaker. In fact, I think their new design even has full 1” type afci nit having the neutral on the breaker. It goes with the rest of the neutrals on the same bar. All these breakers are plug on neutral.

 

[Tulsa Electrician]

Agreed. You often find both legs of a MWBC put on the same phase.

I have seen new work with the black and red on the same tandem.

So true. Ran across this the other day.

 

[Tulsa Electrician]

Same panel. Ooch

This is where all those MWBC went.

 

[don_resqcapt19]

Siemens is making tandem arc fault where the neutral does not connect directly through the breaker. In fact, I think their new design even has full 1” type afci nit having the neutral on the breaker. It goes with the rest of the neutrals on the same bar. All these breakers are plug on neutral.

Yes, the AFCIs that do not have a ground fault protection circuit do not have the load neutral connected to the AFCI breaker. The breaker still needs a neutral connection for the electronics that make the AFCI work.

 

[jaggedben]

So true. Ran across this the other day.

Yes, it seems there's a few guys out there who are completely unclear on the concept and believe that the tandem is supposed to get both wires of the MWBC.

 

[infinity]

Yes, it seems there's a few guys out there who are completely unclear on the concept and believe that the tandem is supposed to get both wires of the MWBC.

I've seen this called out by home inspectors who were too lazy or didn't know that they need to trace the black and red conductors all the way back to where the cable enters the panel. Seems that the sparky alternated the condcutors when he attached them to the tandem breakers so they were wired correctly. This is all out the window now with the handle tie rules for MWBC's.

 

[jaggedben]

Yeah, I mean I've seen a couple panels where when I looked carefully at everything, every MWBC was doubled up on a single tandem. The probability was near certain it was done on purpose.

 

[norcal]

Yeah, I mean I've seen a couple panels where when I looked carefully at everything, every MWBC was doubled up on a single tandem. The probability was near certain it was done on purpose.

If GE THQP, were used it been just fine, or a older Challenger, or Crouse-Hinds panel with twins, guess I should include Zinsco/Sylvania, & FPE too.

 

[jap]

If GE THQP, were used it been just fine, or a older Challenger, or Crouse-Hinds panel with twins, guess I should include Zinsco/Sylvania, & FPE too.

How would using these types of tandems make it any better?

JAP>

 

[jaggedben]

If GE THQP, were used it been just fine, or a older Challenger, or Crouse-Hinds panel with twins, guess I should include Zinsco/Sylvania, & FPE too.

GE THQP is just ... different. I don't call those tandems. The Challenger type A "side-clip" tandem breakers should not be touched except to remove them so I consider that moot. I don't believe you're correct about Crouse-Hinds, but maybe something I never saw. Same with FPE.

Zinsco, I agree, but very rarely would I be willing to work on those either.

The ones I was posting about earlier were none of those. Typical Murray/Siemens or Eaton BR tandems like still sold today.

 

[Crash117]

If GE THQP, were used it been just fine, or an older Challenger, or Crouse-Hinds panel with twins, guess I should include Zinsco/Sylvania, & FPE too.

If you’re not paying attention to a MWBC, both legs can end up on the same phase using GE THQP.

 

[letgomywago]

If you’re not paying attention to a MWBC, both legs can end up on the same phase using GE THQP.

But if using 2 pole ones you shouldn't have any issues