Is there an electrician in the house?

[gottwake]

I have a compressor that I want to hook up and the motor draws 22 amps I guess continuously. Its 240, what would be the recommended wire/breaker make up for this install? This is all the info that I have, lost the manual. There is some stuff on the motor if it helps.

[dmurphy68]

10/3 wire 30 amp breaker

[Bus Ted Knuckle]

It also depends on how far from the service panel the compressor is. The further it is, the larger wire you will need. But you don't want to buy larger than you need-copper wire is higher than a cat's back. If it is within 40 ft or so, 10/3 should be about right. There are charts on the net, google for one, they will tell you what you need with all of your info plugged in.

[lilred67]

Originally Posted by dmurphy68

10/3 wire 30 amp breaker

[gottwake]

The panel is 2 feet from the unit. So you guys dont anticipate a draw upon stratup of more than 30 amps? My A/C has a 40 and runs on less than 10. (so i was told).

[Old Dave]

I'm guessing by the 22A current draw that's probably a 4 or 5 HP motor. 22A x 125% is 27.5A, 30A breaker with 10/3 wire should be fine.

[gottwake]

Dave...Im not sure what that formula was but you absolutly sound like you know what your speaking about. Sounds good to me...thank you.

[shifty]

Question for you: What does the unit say it is rated for, amperage-wise? You say up above "the motor draws 22 amps, I guess"...

When it comes to electricity, it's not something you want to "guess" about. You should look on the unit itself to find this information, or contact the manufacturer.

Electricity is serious. You're basically talking about the difference between your house/garage/shop possibly burning down due to an electrical fire (or not). You can rest assured that if your house/garage/shop DOES burn down, the insurance company will be looking this information up, and refusing to pay out on the claim if negligent wiring is found to be the cause.

Not trying to be a joykill here I'm just trying to look out for another board member!

[gottwake]

Shifty...what exactly am i looking for on the motor?

[raggedjim]

The name plate on the motor should have an area that says "AMPS" or "FLA" (full load amps).


Rg

[shifty]

Try to find how many amps the motor draws. It should be listed on or around the motor, 15A, 20A, 25A, etc.

[Blue'72]

You electrical guys are so shmart. I wish I knew half of what you guys know, but it's all really confusing to me. I got a D- in electronics in jr. high only because the teacher didn't fail anyone...

Just thought I'd give you guys some kudos. Now back to helping get this compressor wired in!

[gottwake]

okay, it says 22 amps.

[dmurphy68]

From What you plate tells me is that the full motor draw is 22 amps... That is a start up draw it should run on less than that after start up. The only way to see the true amps of the motor is an amp probe once you have it hooked up. I do not forsee any problem with 10/3 and a 30 amp breaker

[bigjimzlll]

While a 30 amp breaker may be fine, you may look at getting a HACR rated breaker. At 22 amps FLA (which is low for a 5HP motor) the start up(LRA) could be as high as 45-50 amps(up to 225%).
The HACR(basically heating/AC rated) has a little longer time delay to help offset the start up amps.

I'm sure you'll be fine with a 30 amp circuit. Ideally a disconnect switch with 30 Amp dual element time delay fuses could be used.
To over complicate it even more... a 60 amp disconnect with fuse reducers fed with a 40 amp circuit and number 8 wire would be how I would do it at my house.

The reason for the 60 amp disconnect is because the NEC(national electric code) states that you can up size the fuse for the "motor" protection up to 225% for start up if needed. The biggest fuse youcan put in a 30 amp disc. is a 30 amp. So if you trip the 30 you can put in a 35 or 40 amp fusein the 60 amp disc.

[Thealien]

Originally Posted by bigjimzlll

While a 30 amp breaker may be fine, you may look at getting a HACR rated breaker. At 22 amps FLA (which is low for a 5HP motor) the start up(LRA) could be as high as 45-50 amps(up to 225%).
The HACR(basically heating/AC rated) has a little longer time delay to help offset the start up amps.

I'm sure you'll be fine with a 30 amp circuit. Ideally a disconnect switch with 30 Amp dual element time delay fuses could be used.
To over complicate it even more... a 60 amp disconnect with fuse reducers fed with a 40 amp circuit and number 8 wire would be how I would do it at my house.

The reason for the 60 amp disconnect is because the NEC(national electric code) states that you can up size the fuse for the "motor" protection up to 225% for start up if needed. The biggest fuse youcan put in a 30 amp disc. is a 30 amp. So if you trip the 30 you can put in a 35 or 40 amp fusein the 60 amp disc.

That is all fine and good but if you don't use a motor starter (manual or magnetic) you are not protecting the motor with overloads as required by the national electric code when increasing fuses/breakers for motor start up current.

The fuses/breakers are only protecting the conductors and not the motor. The way I would do it would be a properly sized motor starter fed with properly sized conductors and fuses. I don't like saying too much on forums, I would hate for someone messing up with electricity and burning their house down.

I am an industrial/commercial electrician licensed for 25+ years.

[gottwake]

Okay,
How about this. I will run a 30 amp breaker with 10gauge wire. Basic.

[dmurphy68]

Originally Posted by gottwake

Okay,
How about this. I will run a 30 amp breaker with 10gauge wire. Basic.

Keep it simple stupid if you were going to be using all the time like in a shop i might worrie but not at a house

[gottwake]

Yes...I live by K.I.S.S