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-   -   How would you determine if the wire running TO the box is 200amp? (http://www.diychatroom.com/f18/how-would-you-determine-if-wire-running-box-200amp-70046/)

 hueco 12-26-2015 09:19 AM

by the breaker protecting it or by the wire size. The wire size is the best measure.

 joed 12-26-2015 12:09 PM

The size of the wire determines the max breaker. You can always use a smaller breaker if you want.

 dalepres 12-26-2015 01:52 PM

Quote:
 Originally Posted by hueco (Post 2824738) by the breaker protecting it or by the wire size. The wire size is the best measure.
It's not clear whether you're asking a question, and what that question might be, or if you're simply posting a tip.

Wire is never 200 amp, or 15 amp, or 20 amp. 12 gauge wire will carry 200 amps - for a second or so. Wire has current rating. Circuit breakers have current ratings. You want the rating of the circuit breaker to be less than, or equal to, the current rating of the wire - because you would likely have a fire long before you get to the limit (not the rating) of the wire.

But your subject line seems to ask about the rating of the wire. You can only get that from the wire. The circuit breaker serves to protect the wire should you exceed that rating.

 hueco 12-26-2015 07:20 PM

#12 is never rated for 200 amps, but such a question is about right for a DIY forum and, in fact, there is a whole lot more to it than that. Recommend obtaining an UGLY'S book which is the best, handy reference book to use. My reply assumed the question regarded how one can tell the amperage of a service by the size of the conductors.

 rjniles 12-26-2015 07:59 PM

The size of the service conductors can only show the maximum possible capacity permitted by code. I could use a service conductor with a capacity for 200 amps and use it for a 100 amp service. Or I could us a service conductor with a capacity of 100 amps to feed a 200 amp service. Of course the second example is a code violation.

The size of the service is determined by a combination of the capacity of the meter socket, the service conductors and the main disconnect.

 Jump-start 12-26-2015 10:40 PM

The code permits (310.15 (B) 7 ) incoming service conductors for dwellings to be reduced by a factor of 83% over what they normally would be.

#2 AL is good for a 100amp service and 4/0 is good for a 200 amp service.

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