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I'm working on a GE TM2010S CTL panel to install a generator connection. However the panel is full with two sub-panels.

My plan was to relocate the two 60 amp sub-panel breakers down to make room for the 30amp generator breaker in position 2&4 to allow the main breaker interlock to operate. [See photo of partial work where relocated them to 6&8, 14&16 from 2&4, 6&8]

However, I've since learned that this box appears to NOT allow the use of tandem breakers, however one was previously installed [photo below].

Questions:

  1. Is it okay to position the two 60 amp sub-panel breakers lower on the panel?
  2. Can tandem breakers be used? (The panel states use of THQP [half width] breakers is allowed)

GE Panel Description Panel photo enter image description here Panel wiring diagram

keshlam
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pathfinder
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  • FYI nearly every breaker in that panel is illegal - Type C and BR are not substitutes for GE. You need GE breakers that are listed on label, or other types whose manufacturer has tested for compatibility in GE panels such as Bryant/Eaton type "CL" (but not type BR). – nobody Jul 18 '23 at 01:26
  • @nobody - illegal? or "should be replaced"? I've only heard the Challegers should be replaced. Or would they be illegal because they're not compatible with the GE panel? They were likely installed with the original home construction. – pathfinder Jul 18 '23 at 02:15
  • In violation of NEC since day 1 - breakers used in a panel board must be listed for that specific panel type. Many breakers of the same size will seem to fit but will actually damage the bus contacts. This is separate from the fact that Challenger breakers turned out to be defective. – nobody Jul 18 '23 at 02:59

1 Answers1

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Use THQL and THQP breakers, like the label says

This will afford ample opportunity to access the full 40-pole capacity of this panel.

  • BR and QP breakers do not belong in this panel.
  • Type C breakers do not belong in any panel, as they cheated their UL Listing and do not trip when they should.
  • The two 60A breakers appear to be GE and that's fine. The mystery breaker on lower left costs $7 to replace so I would just do that.
  • THQL is the correct model of full-size breaker for this panel.

The THQP thin 1-pole breakers are half width and must be used 2 per space.

The THQP 2-pole breakers work by using a 1” wide breaker that straddles two breaker spaces. They need a THQP thin 1-pole above and below them to fill out the spaces, though you can daisy chain a stack of THQP 2-poles with only one 1- pole at top and bottom of the stack.

I believe they max out at 50A, however.

The number markings are correct and identify full spaces. With THQP thin breakers it is particularly important to keep your head about where spaces are.

Since you have aspirations to populate the panel further, consider using mostly THQP breakers for plain circuits. This will give you a bunch of gaping holes in the panel cover, fill those with the alien breakers you got rid of. Just don't energize them. I would use the Challengers as empty hole fillers and give away the BR and Siemens to people with those panels.

Beware of MWBC (2 hot 1 neutral) circuits. It is especially important to phase those correctly in a GE panel. I recommend landing each MWBC on a THQP 2-pole, as it's too easy to incorrectly phase them otherwise.

Edit to add photo: odd little cruciforms found where a GE panel supports thin THQP breakers. Photo from electrical-forensics.com

enter image description here

Harper - Reinstate Monica
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  • This box is a TM2010, CTL, with a circuit diagram that shows only 20 poles. So it appears that even using the THQP breakers, its not possible to double the poles. Is this a correct interpretation? – pathfinder Jul 25 '23 at 18:08
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    @pathfinder Possibly, but no need to guess. Pop a breaker off and look for the very distinct "cruciforms" on the bus stabs. See edit – Harper - Reinstate Monica Jul 25 '23 at 21:37