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In my sub-panel that services the home I have 4 separate 20 amp circuit breakers all strapped together to trip all if one trips. On these individual circuits are the garbage disposal, clothes washer, dishwasher and all GFCI circuits? I want to install arc fault breakers but need more slots or room. I would like to remove the 30 amp and 50 amp breakers and install tandem 30/20 and 50/20 and use the strapped together circuits on those 20 amp tandems; is this possible?

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    Please take a photo of your panel and post it. This is pretty confusing. ...Also, why are you installing AFCIs? For what circuits? New or existing? – Speedy Petey Jun 23 '15 at 1:08
  • @Craig - The compact double pole breaker that you linked looks like it would fit into a standard 1" position in the panel. As such it seems that it would only pick up one AC phase. So are you suggesting that for 240VAC application that you use two of these in adjacent slots? If so one would have to link the handles. Easy to see how the adjacent "inside" handles can be linked by conventional means. But then what about the two "outside" handles? Do they may a handle linker that bridges over the two "inside" handles? – Michael Karas Jun 23 '15 at 7:34
  • Hi @MichaelKaras, that's an actual double-pole breaker (both AC phases), with the handles tied. But maybe I'm only thinking of the GE panels that'll take 1/2 inch breakers (I happen to have one in my house). – Craig Jun 23 '15 at 8:12

Any electrician who looks at this would consider that subpanel 'maxed out' ... Not necessarily due to the technicalities of the code to squeeze another circuit or two in with complex tandems but because of the amount of wire packed into that small box and the extreme of things taken to extremes - meaning the multitude of tandem breakers. Generally tandems are used for squeezing in 'one more' or properly upgrading a bath or kitchen on a tight panel. While possible to expand this box is a bit fully loaded as it is.

I would suggest getting a larger subpanel and trying to keep as much as possible as single, standard breakers. You can keep the feed wire and originating circuit breaker (in other panel) the same as long as you're not planning on adding more load. But a new metal panel box is going to be a similar price to a number of $20-30 complex tandems and tandem arc fault breakers.

Here's a subpanel for $75

  • Thanks for your help Neil. I'm not adding any circuits, I need to arc fault protect all outlets except GFCI's, laundry room and garage per code as I'm adding a floor inside the home above the formal living room just like the builder offered when the home was built brand new. We bought the house new after a previous buyer's loan fell through. At that point the house was partially framed and we couldn't make changes like adding the offered bonus room or bedroom. This panel is the result of the new home builder and has never been touched. I'm guessing it's over crowded due to the 6 electrical wal – user38774 Jun 23 '15 at 23:47
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    Tandem GFCIs and AFCIs aren't made at all -- there's simply not enough room for 2 breaker mechanisms + 2 electronics boards in a breaker-slot-sized space. – ThreePhaseEel Sep 8 '15 at 22:02

The only option to do this with your existing box would be to get your paws on a HOMT2020230 and a HOMT2020250 to migrate four of your non-handle-tied 20A circuits to use the same slots as your existing 30 and 50A circuits, along with a HOMT1520 to condense the two bottom circuits into the same slot, and then use the 3 slots this frees up for AFCIs. If you need more than 3 AFCI protected circuits, though, you'll have to go to a bigger box as tandem AFCI's aren't made at all.

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