# wire size amp disco



## Dennis Alwon (May 9, 2009)

myenergy said:


> I need to know the wire size for a 350 amp load on a 500 amp breaker 240/120 volt. single phase commercial service . thankyou


You need to protect the wire at the breaker size not the load. The wire must be good for 500 amps unless perhaps this is for a motor but you stated it is a service.


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## MDShunk (Jan 7, 2007)

No problem, but can you describe the type of load a little better first? That makes a huge difference in these decisions.


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## myenergy (Jan 25, 2010)

Hey Guys This just happens to be a code Question for one of our apprentices. no other details available and the correct wire size is not on the list of answers. just wondering if we can down size. 800kcmill is one of the answers. code reference please


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## MDShunk (Jan 7, 2007)

That's a sucky question. It says this breaker is served by a certain type of service, but it doesn't say if this breaker is part of the service entrance or just a branch breaker; or what type of load. I hate people who write test questions that don't have a clue.


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## Dennis Alwon (May 9, 2009)

My suspicion is they mean service. I would base my answer on 240.6. I let you figure the answer.


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