[carpenterdavid]

I have a 1hp table saw on a 20A circuit, 24 feet of 12g wire. It trips the circuit breaker on almost every start-up, but runs fine, and will start again if only shut off for a minute. Is there a time delay circuit breaker I can use? I have a Square D panel. Thanks

[tkrussell]

The piece of info missing is the voltage. I will assume 120 volts.

A 1 HP 120 volt motor, per code, is to be rated to draw 16 amps, and is allowed to use a circuit breaker no more than 40 amps.

The #12 wire is fine, as the branch circuit must be a minimum of the 16 amps plus 25%, 16*1.25=20.

Try a 30 amp breaker, I bet the unit will start fine.

What has been done is created a motor circuit. This circuit and receptacle is now a dedicated for this motor ONLY.

The receptacle must be a single receptacle, not the typical duplex receptacle, 20 amp AND 1 HP rated.

This circuit and receptacle MUST not be used by anything other than this table saw.

Even thou it came with a straight blade 20 male plug, I usually install a twist lock receptacle and male plug, to insure a motor circuit such as this to make it definitely dedicated for the motor.

Not required by code, (should be) but if I leave a straight blade outlet,it is too easy for anyone to come along and plug some other device in that outlet, and now that motor circuit is not sized properly, and violates code. I like to make things "idiot proof" after I leave.

[LandserElectric]

NEC 210.21B " A single rcpt on an invidual branch ckt shall have an amp rating not less than that of the branch ckt".

Secondly,

Do NOT put a 30a breaker on #12 wire. The breaker protects the wire, nothing else. With all due respect tk russell, what you are suggesting is dangerous, the rest of your advice I have seen on here is sound but I respectfully disagree.

You can put a 40a breaker in as long as you use #8 wire, or a 30a if you use #10. We do this all the time with hvac loads, but if the overcurrent protection goes up, so does the wire size.

You may have just worn out the breaker. Replace it with another identical one. I sometimes change breakers on jobsite temporary panels twice in the same week from heavy use by carpenters. Once the mechanism gets too hot its done for.

If you have used this tool for a while it may be simple as swapping out the breaker.. is this a new occurrence? Did it work for a while before?

Look for evidence of heat on the breaker or bus and also make sure the connection is tight. You are right at capacity so a high resistance connection, whether a joint, breaker, or recep. Terminal may be the problem.

On a related note, I do not allow stab wiring or feed through of plugs on my jobs, I have had a lot of past warranty issues with them. I refuse to believe that knife edge in the stab connection or the little pre-scored tab on the side of the device provide equal or less resistance than a solid mechanical joint. Make sure it's a commercial grade 20a recep as well.

Sometimes what appears to be an electrical problem can be mechanical. A bearing that's bad will cause a motor to trip out breakers and fuses as well.

[Missouri Bound]

Is this a dedicated circuit for the saw? Seems like the breaker may be the issue. I have a 3 HP table saw which starts and runs fine on a 20amp breaker. But then again, how old is the saw? A worn motor may just draw a little too much for the breaker. And as far as the 30 amp breaker.. what does the saw specify? You certainly want enough for the saw to start, but not too much where the saw will not be adequately protected.

[tkrussell]

Land, your correct, I cannot get around Table 210.21(B). If falls before Article 430 and set the stage for cord connected motor. I neglected to back up from Article 430 and comply with preceding articles.

The 1 HP 120 volt motor needs, or can have, a OCPD up to 40 amps, see Table 430.52, however I screwed up leaving the 20 Amp device, even thou it must be HP rated.

The receptacle will need to be a 30 amp device, to match the circuit breaker size chosen to start this motor.

The motor can be hard wired with a disconnect switch, but hardwiring defeats the portability off a table saw.

As far as matching wire size to circuit breaker, that is not necessary once Article 430 and 400 are understood. However I should leave that at the commercial and industrial level, and not give that advice to residential DIY'ers.