Circuit breaker for air compressor

[kevmor99]

I currently have an air compressor, 230V, 12 amps, it looks like it says 2B for horsepower (it's hard to read), I'm guessing it's 2 HP?

It's about 30 feet from the panel and I'm looking to add a quad tandem breaker as it's out of space. If NEC says I can size the breaker to 250% of the amps, does that mean I can use a 30 amp max breaker?

Also, I'm thinking of using larger wire in case I'd like to upgrade way down the line, so if I ever got a 5 HP compressor I wouldn't need to run a larger wire. What wire would you recommend? I think at my old house I was using 12/3 wire, but would 10/3 be better in this case?

 

[alfredeneuman]

I'm thinking of using larger wire in case I'd like to upgrade way down the line, so if I ever got a 5 HP compressor I wouldn't need to run a larger wire. What wire would you recommend? I think at my old house I was using 12/3 wire, but would 10/3 be better in this case?

A neutral is not necessary, so it only needs 2 wires and a ground
A 5HP motor can't be installed with #10 Romex, it's got to be individual conductors in conduit.
If Romex, it would need to be #8

 

[wyliesdiesels]

Are you wiring this 2HP compressor with a cord and plug? If so then you cannot size the breaker more than the outlet rating. The 250% factor is only for hardwired motor circuits.

Can you post a pic of the nameplate?

 

[kevmor99]

That makes sense, it currently has a NEMA 6-20R plug on it, so the max breaker would be 20A to match that? Is the 20A receptacle rated at the running amps or does it take into account the starting amps?

Here's the name plate: https://ibb.co/59MZXVz

 

[wyliesdiesels]

That makes sense, it currently has a NEMA 6-20R plug on it, so the max breaker would be 20A to match that? Is the 20A receptacle rated at the running amps or does it take into account the starting amps?

Here's the name plate: https://ibb.co/59MZXVz

For a motor circuit the receptacle needs to be rated for the same or greater HP as the motor. The running amps is inconsequential. And the starting amps is 4x-8x the FLC which would could be close to 100a but only for 100ms or so...

I'm not sure what 2B is. might have something to do with the duty factor...

 

[u2slow]

That makes sense, it currently has a NEMA 6-20R plug on it, so the max breaker would be 20A to match that? Is the 20A receptacle rated at the running amps or does it take into account the starting amps?

Here's the name plate: https://ibb.co/59MZXVz

My 16A @240V compressor uses a 6-20P cord, and a 20A breaker. No issues.

https://www.grainger.com/product/SPEEDAIRE-3-0-HP-1NNF7

 

[mike93lx]

Is it a hard run? If not, just install what you need now and worry about new wiring when a new compressor comes

 

[pancho400cid]

My guess is the motor is rated at 2HP with class B rise temp.

The motor doesn't have a service factor and the insulation is Class B so at 2HP continuous the motor would be operating with no thermal margin... You're running at the max temp the insulation is rated for.

A more expensive motor might have class B rise at rated HP, but class F insulation so would have some thermal margin and would possibly have a service factor of 1.15 as a result.