1. Originally Posted by Smart \$
OP'er simply wants to know if a multi-pole contactor rating of 30A means 30A per pole or 30A total.
And what would be the difference between the two? In what context does the word "total" come into play here? If you put two lights in parallel, with one drawing 1 amp and the other drawing 2 amps, then the two lights draw a "total" of 3 amps. But if you individually measure the amps flowing in each of the two poles of a 2-pole contactor, and if your meter gives you a reading of 15 amps in each case, are you going to conclude that the contactor is experiencing a "total" current of 30 amps? I hope not. This is not an "amps plus amps equals amps" situation. It is an "amps flowing out equal amps returning" situation.

2. Originally Posted by charlie b
Those two statements are saying exactly the same thing! Please do not think that 30 amps going across each pole of a two-pole contactor gives you a total of 60 amps. The 30 amps that are leaving one pole are exactly the same 30 amps that will be returning on the other pole.
With single phase, would you switch both live and neutral?

3. Originally Posted by charlie b
... It is an "amps flowing out equal amps returning" situation.
But the amps flowing out through one [set of] contact[s] doesn't necessarily return through another [set of] contact[s]. It could be connected to all single phase L-N loads, where the current flowing out through contacts returns on unswitched, individual neutrals... or all L-L loads with only one leg switched (though this is not the typical configuration, but not prohibited by Code).
Last edited by Smart \$; 09-05-12 at 12:33 PM.

4. Originally Posted by Besoeker
With single phase, would you switch both live and neutral?
Single phase could be two pole (i.e., 208 volt), and thus not have a neutral. That was my interpretation of the question.

5. Originally Posted by Smart \$
But the amps flowing out through one [set of] contact[s] doesn't necessarily return through another [set of] contact[s].
OK, I see where we are getting confused. Or maybe it is only me that is confused. I interpreted the question as dealing with a device that has two things that open and close together on command, and that serve a single load, so that current leaving the one will return via the other. You are talking about multiple sets of contacts, all operating together, but serving different loads. So that brings us back to Jim's original response, that any pole can handle 30 amps. Mea culpa.

6. Originally Posted by charlie b
OK, I see where we are getting confused. Or maybe it is only me that is confused. I interpreted the question as dealing with a device that has two things that open and close together on command, and that serve a single load, so that current leaving the one will return via the other. You are talking about multiple sets of contacts, all operating together, but serving different loads. So that brings us back to Jim's original response, that any pole can handle 30 amps. Mea culpa.
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