New construction wired by professional electrician, Montana USA. Dedicated circuit for a 14" chop saw with 10 ga. wire and a 20 amp breaker. Saw was used previously on a 15 amp circuit with no problems. The saw is rated to draw 15 amps. The saw is a 14" Milwaukee abrasive wheel cut off saw with cord and plug, it is plugged into a 20 amp duplex GFI outlet. It trips the breaker immediately upon energizing. The electrician says he can not install a 25 amp breaker as it would be out of code. Any suggestions? In the comments section of this question mention was made to slow blow circuit breakers, I have been unable to find any information on these. Does someone know where info. can be found? I tried Square-D's site.

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    Does it trip when you plug it in, or when you pull the trigger? How old is the saw? Does the saw work when plugged into another receptacle, what about another receptacle on another circuit? – Tester101 Mar 15 '15 at 18:44
  • Is it a GFCI breaker? – friedo Mar 15 '15 at 20:15
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    Motors often have higher than rated startup loads. (As an example, my 15A compressor draws almost 30A for just a moment.) Ask your electrician about slow trip breakers. – Aloysius Defenestrate Mar 15 '15 at 20:41
  • Best option IF possible (likely not, but worth checking) would be to switch the saw to 230V operation. Otherwise using a breaker that has a slower trip would be the norm. – Ecnerwal Mar 15 '15 at 20:47
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    It seems that all the comments miss a critical point: Does the saw still work properly when plugged into the old 15 amp protected circuit and/or any other circuit in the house/garage/shop? If so, it sounds to me like it's an issue with the new circuit. – FreeMan Mar 16 '15 at 13:53

10 gauge wire can have a 30 amp breaker under the current National Electric Code. (and past ones too). Most places use the NEC, but some make changes.

I do not have my book right here, but if needed I can get you the exact section in the code for that data.

I am 'sure' he carries a current copy of the NEC with him, for reference.

Aloysius is also completely correct, a 15 amp rated motor will draw a much higher momentary start-up current.

The current will also increase if you stall the saw.

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    Throwing a bigger breaker at the problem is likely a band aid, not a solution. – Tester101 Mar 16 '15 at 11:32
  • Understood and accepted. The questions I attempted to answer were the issue of the 25 amp breaker being out of code, and a possible reason for a saw to trip a 20 amp breaker. I do not know of a source for a thermal only, or at least variable magnetic trip breaker for a load center built to the newest building codes. So on that question, I provided no information. If you will look at his follow-up top level question, and read the information posted there, you will see that I identified a breaker by part #, a question about the series of his load center, and a complete reference point in the NEC – Some Guy Mar 16 '15 at 14:08
  • @SomeGuy, the problem is not with a 30A breaker and #10 wire. The problem is with a 15 or 20A receptacle and a 30A breaker. ..... Also, he states it previously worked fine on a 15A circuit. Obviously this is not an issue with startup current. – Speedy Petey Jan 8 '17 at 14:00
  • You need to look at the parts of the Code which say which receptacles can be on which breakers. The fastest way to find this is exact phrase search "15 or 20". That refers to which breakers may feed the common NEMA 5-15 recep. – Harper - Reinstate Monica Sep 21 '19 at 20:48

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