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Just to clarify, how does two 30A breakers on different phases equal 30A?


Think of a 220volt center tapped transformer. This is, essentially, what feeds USA houses. There is only one phase, but two "legs". Usually the center tap is tied to ground at the house breaker panel and we call it "neutral". For a 30 amp circuit, it would seem that a one pole 30 amp breaker is enough, but since both legs are hot with respect to neutral and ground, both legs must have a breaker. For 220v loads, the 30 amps on both legs is the same 30 amps, it's not additive.

For 110 volt loads, it does appear that the breaker delivers 60 amps, but the loads, if equal, balance on the two legs and becomes a single 220 volt load. Double the voltage, half the amps, so two 30 amp 110 volt loads becomes a single 30 amp 220 volt load.

There did exist here in the states a two-phase electrical system that required four hot wires that all had to be connected correctly to work. It was kind of a precursor to three-phase, that requires only three wires and, for the most part, can be connected in any way. I think the last two-phase electrical distribution system here was decommissioned back in the '70s.

Stepper motors are two phase.

I'm jealous of our EU friends, they get three phase to their houses. I don't even have three phase to my industrial shop...

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Not trying to argue, but it seems that each leg is capable of pulling 30A, independent of the other.


They are not independent. You can get a single 110v load to pull 30 amps and return it on the neutral, but once you start adding 120v loads on the other leg, you lose current flow on the neutral. With two identical 120v loads, there will be no current flow on the neutral. They become a 220v load.

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As to the 8:1 bend ratio, how can that even be possible in most (at least, my) circuit panels? I only have 2" or so to go from vertical to horizontal on my wires. This doesn't seem like enough physical space for a 4-6 gauge wire. Not to mention the 0 gauge mains that turn in almost as little radius.


A #4 is 0.2" diameter, so 8x is only 1.6" radius. Typically, the big feeder wires come from the top and don't bend much getting to the lugs. Of course, this doesn't mean that your particular panel is done this way. Electricians know very little about wires...