12/3 wire, two separate circuits
I live in an old house, with 2 apartments, that still has fuses. The electrical wire that supplies the kitchen is 12/3. One 20 amp circuit supplies the fridge, the other 15 amp circuit supplies the outlet on the counter and the light over the sink.
I've read this type of setup is acceptable if the two circuits are on separate poles (or leads). If the two circuits are on the same pole, the neutral wire can be overloaded. But all of what I've read refers to circuit breakers, not fuses.
My fuse box has 6 round fuses; 3 on the right side, 3 on the left. The circuits in question are both on the left hand side, one above the other.
I've read that to tell if the circuits are on separate poles is to test the voltage between the 2 circuits. If you get a 240 volt reading, the circuits are on separate poles and are safe from overloading the neutral. But if you get 0 volts, the 2 circuits are on the same pole and are not safe.
I tested the voltage and it is ZERO between the two circuits. If I test a circuit on the left with a circuit on the right, I get the 240 volt reading.
From my understanding I need to switch the wires so one is on the left side and one is on the right side; which will be fairly easy to do.
But I want to be sure this is what I'm supposed to do before I go ahead.
From my understanding this house was split into 2 apartments sometime in the 60's, so this electrical setup with the 12/3 wire has been in place since that time, with no know problems. (house still standing!!)
Any advice would be a big help.