GF, in a fairly old mid-1900's house that she's renting. Electrical system has been replaced since the house was built (breakers instead of fuses) but it's still pretty old stuff. House has had some modifications, like the garage being turned into a den and a loft office, and there's been some crazy work done on the electrical panel. House contains some old electric baseboard heaters (on their own circuits) which she is supplanting with some more modern space heaters plugged into AC outlets.

She says that she doesn't understand something about the circuit breakers, and that Google isn't helping her find what she needs to know. So I said I'd ask here. If necessary, I can get photos this weekend.

She says there are some circuit breakers which appear to be two 15-amp small-size breakers next to each other. And they are connected together at the switches so that when one trips they both trip. But they appear to be separate breakers.

My first reaction was that they were actually a larger "ganged" pair to give more amperage. But she says that is not the case, and that her googling says you can't do that anyway (ie, make a 30 out of two 15s). Also, her empirical experience is that they're just a pair of 15's, because she can run one space heater on one of those circuits but not two of them (the space heaters draw about 10-ish amps each).

My question is: Has anyone seen this trick where there are two 15-amp breakers connected together? And what is the purpose for connecting them together? If they are on different circuits, why gang them like that?

I might be able to get photos this weekend.