As in a condo complex with the outside units fed via a bank of larger breakers just below the meter in the garage. Supposedly the one on there now is a 40/40 "piggyback" and I need to change it to a 40/20.
What's the story with these? Does one side of the breaker feed the other? Another case where I'll have to do some walkin' back and forth as right now the installers don't know which side of the breaker feeds the disconnect as they are both 40s. Got a 50/50 shot on the first try, though...
Why would there be a need for a piggyback? Space contraints? Why not just use skinnys?
Piggyback is two single pole breakers fed from a common bus clip in a single slot case. I've never seen them with two different values. You may have to combine some household circuits together onto 20/20 (or 15/15) to make room for the one you need. They're pretty common in the QO and HOM panels. Beats the heck out of putting in a bigger panel or a sub panel.
Well...I don't know if our guys are using the term correctly. I also heard the term quad bank or quad pack...quad something.
I don't understand why they did it like this, but here it is. Essentially it's just two single pole skinny breakers paired up per 240 load to catch both legs. You then have to connect them so if one trips they both trip. Simple as that. You'll note the middle two have a clip that fits over the throws, and the outer two are connected by a bracket with nipples that fit into a hole in the side of the throw. We're more used to seeing a bar or pin that connects the throws.
For the life of me, I can't understand why two regular fat breakers side by side would accomplish the same goal much easier. The load center wasn't built to accomodate any more breakers anyway, fat or skinny.
We basically have four skinny single pole breakers behaving as two double poles; with bracket-type whachamahickies ensuring that if one pole trips, the other will as well to ensure that improper voltage will not be fed to the device and someone will not be harmed by the remaining leg of power.
I'm just not sure of why it was done in this manner way back then (about 40 years) and suspect it was simply for versatilty. It's a condo situation with the 120v 15 and 20 amp breakers in the dwelling and the 208-230 2 ploes in the garage below.
If there are any lingering questions I'll send the picture to my electrician buddy around the corner and have him explain...?