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#14703 - 09/29/02 09:04 PM 3 phase amperage
aldav53 Offline
Member

Registered: 08/22/01
Posts: 547
Loc: Chandler, AZ USA
Just to confirm my thinking, on a 208v 200a 3ph service, (providing the wire is the correct size), is good up to 200amps per phase measured with an amp clamp.
But the total would not be 600 amps, correct?
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#14704 - 09/29/02 10:32 PM Re: 3 phase amperage
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
If you have 200A being drawn on each phase, then no, you can't really say that the total is 600A because of the 120-degree phase difference between phases. That same phase difference is the reason why if you have exactly the same current flowing on each phase then the neutral current will be zero.

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#14705 - 09/29/02 10:52 PM Re: 3 phase amperage
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
I would say that you are correct, it depends upon the size of your protection on the circuit and the cable size.
You would think that you could directly add the line currents together, unfortunately, this not so, .
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#14706 - 09/30/02 07:07 PM Re: 3 phase amperage
jlhmaint Offline
Member

Registered: 05/25/02
Posts: 208
Loc: Fredericktown, OH, U.S.A
you are correct. 200amps is what you will read on each leg but you don't add them up. It is just 200amps

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#14707 - 09/30/02 09:31 PM Re: 3 phase amperage
aldav53 Offline
Member

Registered: 08/22/01
Posts: 547
Loc: Chandler, AZ USA
If one of the legs was a 208v to grd wild or high leg, I assume it would still be the 200amp max on each leg, on a 200a service. Also correct?
Thanks for your help,
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#14708 - 10/01/02 03:44 PM Re: 3 phase amperage
arseegee Offline
Member

Registered: 01/28/02
Posts: 321
Loc: Statesboro, GA USA
If your B leg is 208 to ground, you're on a delta secondary and thats actually a 240/120 delta. But youre still a 200A service. You will read 240 between phase to phase.

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