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I have a 1.5 hp table saw motor rated at 115v/16amp. My garage has all 20 amp breakers but all outlets are 15 amp. Does the 15 amp outlet present a hazard if the wiring and circuit are all rated at 20 amps?

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Just change out the receptacle

I bet your tablesaw has a 5-20 plug on it, which won't fit into a 5-15 receptacle. Since you have a 20A circuit, though, there's nothing wrong with having a 5-20T duplex receptacle on it, or even changing all the receptacles on the circuit to 5-20Ts from 5-15s. This shouldn't be too tricky a job, as long as you turn off the breaker before you start (of course), change the receptacles one at a time, and note down how things were wired before you start unhooking them. Also, if the existing receptacle is a 15A GFCI, it'll need to be replaced with a 20A GFCI, not a regular receptacle.

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    Or the GFCI could be moved upstream and this outlet powered off it LOAD terminals. – Harper - Reinstate Monica Dec 23 '19 at 4:10
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    @Harper-ReinstateMonica True. But the simplest thing, by far, if the existing receptacle is a 15A GFCI, is to replace with a 20A GFCI. Replacing upstream will actually cost $1 more (because you are then replacing 15A GFCI with 20A plain and 15A plain with 15A GFCI) and can lead to the LINE/LOAD confusion. So a single straight replacement makes the most sense. Of course, we're all just guessing as to whether the existing receptacle has GFCI anyway. – manassehkatz-Moving 2 Codidact Dec 23 '19 at 4:48
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    @manassehkatz no no, no, you'd just move the GFCI you already own, to the upstream location. – Harper - Reinstate Monica Dec 23 '19 at 6:25
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    @Harper-ReinstateMonica Oops. You're right (as usual!). But it still raises the issue of getting LINE/LOAD messed up. – manassehkatz-Moving 2 Codidact Dec 23 '19 at 6:26
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    Don't forget to mention that OP needs to check whether the wiring is 12-gauge or better. – MonkeyZeus Dec 23 '19 at 13:55
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All of this is safe, except you cannot plug in the table saw.

What, you say? The table saw has a common-as-dirt NEMA 5-15 plug? How did that get there? That right there is the fly in the ointment. No, that is not safe. A 16A motor needs a NEMA 5-20 recep. (unless the motor has some very peculiar characteristics in which it's allowed to use a smaller plug AND breaker, but you do a specialized rain dance with Code to see if that is so).

However, there is nothing wrong with plugging a mix of 15A and 20A receps into a 20A branch circuit.

Make sure that if this recep is GFCI, that you either replace in-kind or move the GFCI recep to an upstream location and feed this location off its LOAD terminals. 15A Receps are supposed to be rated for 20A passthru, and that includes GFCI receps.

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Short answer is yes. If your table saw motor gets pinned down and is pulling > 15 amps, you've exceeded the specs for the outlet and it will get nice and warm. This causes the contacts to degrade and eventually introduce a good fire hazard. The longer you run it over its rated amperage the more likely you are to start a fire.

I'd replace the socket with a 15/20 socket like so: https://bit.ly/34SZTvs

My table saw has similar ratings, and to be honest as long as you don't put a ton of load on the blade the current will stay less than 15 amps. I've been running mine on a 15amp socket and breaker for 8 years. Have blown the breaker a couple of times when a piece got stuck, but my house hasn't burned down yet.

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