120/277 DP Breaker

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Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
A friend sent me an email asking why a dp breaker rated 120/277 cannot be used for 240 Volts. I have never noticed a breaker rated that way. Any help.
 

augie47

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Tennessee
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State Electrical Inspector (Retired)
My first though would be to refer him to the "eyeglasses at Wal-Mart" thread :)
 

don_resqcapt19

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Illinois
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retired electrician
A friend sent me an email asking why a dp breaker rated 120/277 cannot be used for 240 Volts. I have never noticed a breaker rated that way. Any help.
If it was actually marked that way, there is no reason why you can't use it on a 120/240 volt system. The first number is the maximum permitted voltage to ground and the second is the maximum permitted phase to phase voltage. You could not use it on a 3 wire 240 volt system because of the 120 volt part of the "slash" rating.
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Well thanks for the replys but apparently he was talking about a DP switch not a CB. I guess I never look at them -- they are rated 120/277. I told him exactly what Don said. Thanks again and sorry for the confusion-- I should know better than to post for someone without all the info.
 
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