I have an installation of a new compressor rated 330A. The manufacture reccomends fusing at least x1.15. This is ~380A. I have an existing feed utilizing 500MCM which is good for 380A. Can I fuse at 400A since my load is still under the ampacity of the wire? Code reference? Thanks.
Fusing Question
- Thread starter Mike4806
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- Lockport, IL
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- Semi-Retired Electrical Engineer
Yes you can. 240.4(B) allows you to go to the next higher standard rating, and 240.6(A) has the standard ratings.
Welcome to the forum.
Welcome to the forum.
1.15 seem like that may be overload setting, not fusing. You can go up to 1.75 x FLA for a compressor. Also if the compressor is a continuous load, you must use the FLA x 1.25. So your fuse size may be as high as 600 amps and wire capacity 330 amps x 1.25 = 413 amps. If this is correct the 500 kcm would not be adequate. Suggest you verify these figures before you go any further.
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