Panel board I have not seen before

The breakers (OK one) had a hole for insertion perhaps of a cartridge fuse ? (not sure)
The one listed as 20 had a pull out with two mini cartridge fuses listed at 20 amp each.
Someone please tell me about these.
They were in a Condo (so they are in a sub)
Not looking for fun issues ,just facts on the breakers.:wink:

These are QF type and installed in 1970

Thanks in advance.



Paul are you out there?

I just swapped out a panel that was an older QO style. It was more than 50 years old but still worked like a charm for a main panel. I would imagine it’s the same concept as the one I did. Each breaker had two handles to it as well as two lugs. They fit on the buss just like any other breaker. Two separate branch circuits would then connect to the two screws/lugs on the breaker. If you look at the panel diagram/label, you’ll see each one listed with an R. That is labeled for the Rear terminal. I don’t see why the cartridge fuse pull-outs would be any different. Instead of the breaker having two throws on it, you have two fuses inserted into the pull-out.


Thanks Jeff.
I still do not understand the empty space on the far left breaker in the middle of it .
Apparently for a cartridge.
Never saw anything like it before.

Strange days, as I just finished three in a row with Ceil Heat.

That’s most likely where the second pull-out fuse is located. Apparently missing.
I gotta get out of the suburbs and go into the city for some of the more interesting things you are discovering. I’m lucky if I come across a true crawlspace with an entrance from the outside.


The labels clearly say Square-D. Is that what you are asking?

Looks like cartridge fuse panel to me… perhaps an intermediate between edison fuses and IDE panels made by Siemens at one time. The cartridge is missing as you have pointed out. An antiquated unit and difficult to find replacement components