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Available Short Circuit Current?
How does the Canadian code deal with the available short circuit current available from the utility transformer feeding say a residence or dwelling?
We in the US have to have a Main overcurrent device that can shut the systems power off before the max. can build up to a dangerous level. http://www.hostboard.com/ubb/smile.gif
Ronald
Just curious how canada deals with this problem?
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Ronald,
There are no specific rules regarding available fault currents in dwellings. There is only a general rule stating "equipment required to interrupt fault currents shall have ratings sufficient for the fault current available at the terminals".
I guess they are assuming the transformers used to supply a typical single family residential service would not produce fault currents exceeding the 5000 A interrupting rating of a standard circuit breaker.
Ed
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Hello Ed:
Sorry took so long answering your reply.
About ten years ago we had one electrical inspector that was a fanatic on Ic rating of Main Breakers.
But now the newer breakers usually have an Ic rating to do the job without having to speacial order them. http://www.hostboard.com/ubb/smile.gif
Just curious about some of the differences between the Canadian and US codes.
Thanks very much for the reply.
Ronald
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