120/240V single phase amps?

[Caleb20]

I have been racking my brain and just cant rember the answer to this question.

If you have a single phase 3 wire two hots and a neutral service that is 120/240v and a 100A main how many amps can you draw total? I know this is probly a stupid question but i am getting hung up on the fact that if I draw draw 100 amps from one of the 120v feeds and 100amps from another 120v feed am i drawing 200A from the transformer up stream of jsut 100Amps?

 

[dpc]

100 A.

David Castor

http://www.cvoes.com

 

[Compositepro]

100 amps at 240 or 200 amps at 120. Same power for both. But you cannot put 200 amps at 120 through one load. It would have to be 2 separate loads of 100 amps at 120. You basically have two secondary coils in the transformer that are rated 100 amps at 120 volts that are in series so you cannot parallel connect them.

 

[dpc]

100 amps at 240 or 200 amps at 120

Well, a circuit breaker knows nothing about voltage at least as far as current carrying ability. A 100 A breaker can carry 100 A. (Actually 80 A continuously).

As far as the transformer, current can't flow in only one leg of the secondary. If 100 A are going out on one leg, 100 A is returning somewhere.




David Castor

http://www.cvoes.com

 

[waross]

You are fed from a 240 volt transformer with a center tap. That gives you 120/240. Your 100 main breaker will allow a maximum 100 amps to pass on either hot leg. If the loads on the hot legs are unbalanced, the difference will return on the neutral, but the maximum allowed is 100 amps at 240 volts.

Bill
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