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#14703 - 09/30/02 12:04 AM 3 phase amperage  
aldav53  Offline
Joined: Aug 2001
Posts: 545
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 - 09/30/02 01:32 AM Re: 3 phase amperage  
pauluk  Offline
Joined: Aug 2001
Posts: 7,520
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.

#14705 - 09/30/02 01:52 AM Re: 3 phase amperage  
Trumpy  Offline

Joined: Jul 2002
Posts: 8,217
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, [Linked Image].

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#14706 - 09/30/02 10:07 PM Re: 3 phase amperage  
jlhmaint  Offline
Joined: May 2002
Posts: 202
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

#14707 - 10/01/02 12:31 AM Re: 3 phase amperage  
aldav53  Offline
Joined: Aug 2001
Posts: 545
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,

The Golden Rule - "The man with the gold makes the rule"

#14708 - 10/01/02 06:44 PM Re: 3 phase amperage  
arseegee  Offline
Joined: Jan 2002
Posts: 324
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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