Hot Topics: Adding Twin Breakers to a Subpanel

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Original Post: Adding twin breakers to a subpanel

n1ml Member

Adding twin breakers to a subpanel

I have a Cutler Hammer, CH7GG, subpanel in my garage. There is another subpanel as well as a main elsewhere in the house.

The panel has 42 3/4” spaces. The present complement is:

9 two pole breakers

22 single pole breakers

2 twin type breakers (two single pole breakers in a 3/4” package)

I need to add another two pole 240 vac, 15 amp breaker for a compressor.

Can I add two more twin type breakers to make room for the new compressor circuit?

ibpooks Forum Topic Moderator

I don't recognize CH7GG as a valid Cutler part number, but generally speaking a 42 space panel will not be rated for any tandem breakers. Can you read the allowed breaker types on the label inside the panel door?

n1ml Thread Starter

CH7GG is stamped above the breakers. The only label is a place to list the circuits for the breakers. There is no typical label that defines the breakers. It does take Eaton or Cutler Hammer type CH breakers, like CH230.

There is no main in the panel, only lugs above the 42 slots. It is fed from a remote panel that has a 200 amp breaker and another 50 breaker that feeds a different subpanel.

Tolyn Ironhand Group Moderator

Look at the label inside the door of the panel.

n1ml Thread Starter

That is the problem. The only label on the inside of the door says Cutler-Hammer, Safetybreaker Load Center and has 42 lines in which to describe what the breaker position does. There is also a "Danger, Electrical Shock" warning sticker. A "Ground Fault" warning label was added. The house was built in 1991.

I have seen the types of labels that describe panel specifications but there is no sign there ever was a label like those.

ibpooks Forum Topic Moderator

If it's from the 1990s, then it definitely can't take any tandem breakers. Panels weren't allowed to have more than 42 circuits until well into the 2000s.

What that means is that the panel is already overfull with the two tandems currently installed. Usually in this case the best fix is to install a subpanel right next to this one. Move the four circuits on the two tandem breakers over to the new subpanel, which will free up two slots for the breaker to feed the subpanel.

CasualJoe Member

I'd try removing the cover/door and looking for a label inside the panel box, probably on the left side. In past years CH series panels had the cover/door sold separately so the actual panel label was always inside the box.

"If it's from the 1990s, then it definitely can't take any tandem breakers. Panels weren't allowed to have more than 42 circuits until well into the 2000s."

Agree completely. I believe it was somewhere around the 2008 NEC that allowed more than 42 circuits in one panelboard.

n1ml Thread Starter

Removed the cover and there is no label inside the box or on the back of the cover.

I do have a question after reading a lot of internet info and getting confused.

My dryer circuit breaker, 240vac, 30 amps, takes up two spaces but I would consider it one circuit. Is this correct?

CasualJoe Member

"My dryer circuit breaker, 240vac, 30 amps, takes up two spaces but I would consider it one circuit. Is this correct?"

That's correct, it is one 120/240 volt circuit, but the breaker uses two pole spaces. When the code calls out 42 circuits as the maximum per panelboard, it is referring to pole spaces.

n1ml Thread Starter

Gotta start to plan on adding another panel next to this one.

Too bad it is in a flush mounted finished wall. Oh well.

This 42 space panel is fed directly from a 200 amp breaker about 65 feet away. I am thinking a 12 space Cutler Hammer panel would work. The other two house panels use CH breakers, so I thought I could keep all the same throughout.

What size feed breaker should I use in the existing panel to feed the new panel?

ibpooks Forum Topic Moderator

You can use up to the maximum rating of your new panel. For a 12 space, that usually will be 100A. Assuming you connect it via a conduit nipple to the next stud space over, you can use #3 copper wires in black, black, white with #8 green ground.

n1ml Thread Starter

I will plan to move the two tandem breakers over to the new panel and use single standard breakers. That would give me the two poles I need for the new 240vac circuit.

Do I have to move the hot, neutral and ground for each of the four circuits or can I just wire nut the hot in the old panel and connect it to the breaker in the new panel? That would be just four splice connections instead of 12.

At first glance, the new panel ground and neutral bus is just connected back to the old box busses. At second glance, it sure would confuse someone only looking at the new panel. The original installer did an excellent job making the inside look neat and uncluttered. I want to keep it that way.

Ibpooks Forum Topic Moderator

Yes to avoid confusion and make a neat installation all wires should come from the new panel. The electrons don't care, but it is much easier to understand for a future serviceman who opens up this panel.