I am considering replacing the motor on my Inca table saw (Dayton 1.5 hp 115v/16.4amp) because I only have 115volt/15amp power in my new shop.

I have found a Baldor 1.5 hp motor with 115v/12.4amps. Should I expect this motor to have appreciably less power than the 16.4 amp motor it is replacing?

  • Are you tripping the 15 A breaker with the current motor? – Mark Feb 6 '20 at 2:29
  • @Mark, I haven't even tried to run this saw on the current breaker. It's a different plug than I have outlets for. – Joe Feb 6 '20 at 2:40
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    15A receptacles are allowed on 20A circuits, so the first question is are any of the receptacles in your garage on a 20A breaker? You might just need to change a receptacle. – NoSparksPlease Feb 6 '20 at 2:51
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    What kind of plug is it? Can you pick it out of a lineup? (these being sockets, so flip them vertically in your mind). – Harper - Reinstate Monica Feb 6 '20 at 2:58
  • The current plug is a NEMA 5-20 @Harper-ReinstateMonica but I was planning to replace it with a NEMA 5-15 after changing to a lower amp motor. – Joe Feb 6 '20 at 3:29

In the vast majority of 120V-land, this is an easy problem to solve. Way easier than the $543+tax+shipping a 51-pound motor that will make your saw underpowered.

Many circuits with the familiar receptacle are actually on 20A circuits

Because there's an exception in Code that allows the familiar NEMA 5-15 recep to be used on 20A circuits (as long as there are 2 or more sockets in the circuit). The point of this rule is so the builder can just use the same recep everywhere.

If the breaker is 20A and the cable is 12 AWG copper, then you absolutely can just change it to a NEMA 5-20 20A receptacle. And, it's backwards compatible with NEMA 5-15, so your old stuff will still plug in.

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Changing the receptacle is such a simple and straightforward job (well, mostly) that inspectors exempt it from the usual rules about pulling permits, tenants not being allowed to do it in rental properties, etc. You still need landlord permission.

A new dedicated circuit is fairly cheap to put in

A new circuit to serve any of the above-pictured receps can be run for about $40 in materials, + labor. $550 is a lot of labor. In fact, if you have any notion to do this with 240V circuits, now's the time before your state enacts NEC 2020, which will require a $80 GFCI breaker on 240V circuits.

  • So I do have 20 amp breakers running to the 15 amp outlets in my shop. Would it be a code requirement that 12 gauge wire connects the 20 amp breakers to the 15amp outlets? I live in California. – Joe Feb 6 '20 at 21:55
  • I thought so. You're almost home. Yes, the 20A breakers need to go with 12 AWG wires, but that is most likely already the case. Don't use backstabs, but an easy way to test is to push it 1/16" in to a backstab hole on a cheap 15A recep. #14 will go through the plastic hole easily, #12 won't. Recently made Romex is now yellow for #12, but #12 also exists in white. – Harper - Reinstate Monica Feb 6 '20 at 21:58

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