Question
I'm scratching my head trying to understand why my Sub Panel was set up using the tandem breaker configuration described (with picture) below.
There are 3 tandem breakers, with the top two on the top breaker slot and the 3rd breaker on the next slot down. You can also see a cover where another tandem breaker for the second slot might normally be. There's also what I believe is a "cheater bar" across the bottom two breakers tying them together.
Why are the bottom two tandem breakers tied together across two slots like this? And, possibly worse, why is there another non-joined tandem breaker sharing the top slot. Best case this is some complicated scenario I just don't understand. Worst case this is a problem and I need to re-wire my subpanel (which I might do anyways for sanity).
Background
I understand tandem breakers allow you to use the same breaker slot for multiple circuits (with caveats). I also understand that you can tie multiple breaker slots together to control phasing or create a 220v circuit.
However I can't quite make sense of what's happening here. There aren't any 220v circuits that I'm aware of and that'd be a problem anyways as these are 15A breakers, wouldn't it? I can see 4-5 separate circuits in my garage attic which are all tied to these two breakers. Note the circuits aren't under heavy load: a few lights, 1 outlet and the garage door opener. I haven't looked yet to see if all of these circuits go directly to the breaker or if there's a junction box hidden somewhere in my house.
Maybe I'll pull off my panel cover and discover some weirdness on my panel itself leading to this setup, but this configuration seems suspicious. And there's so much room on this panel. I don't understand why tandem breakers were even necessary.
It's also possible that the cheater bar is there purely to turn off all power to the garage if either breaker is tripped, maybe as a safety feature.
Any thoughts?
Thanks!
Best Answer
A pic of the innards of the panel would help, but it's mostly likely a MWBC (Multi Wire Branch circuit) for your garage lights. If so, it's required that the breakers feeding it are handle tied like in your picture. Seems like over-kill for a lighting circuit unless there were lots of high wattage incandescent lamps in the original installation.