Wiring questions for new 7.5HP 220v compressor

[767Jockey]

My trusty old 5HP 60 gallon Sanborn just died. Figuring that this will be the last compressor I buy, I went overboard and bought a Ingersoll Rand 7.5 HP single phase 80 Gallon Two Stage unit. It's Ingersoll Rand model number 2475N7.5.

When I wired the garage I put in larger circuit wiring for the compressor than the old Sanborn required, figuring that I'd buy something bigger down the road. I have it on a 40 amp breaker with 6 gauge wire. From what I am reading, this seems sufficient for the new compressor. It's about a 25 foot run from the breaker box to the compressor. Does that seem sufficient to you electrical gurus?

This unit come with a magnetic starter. I wired the old Sanborn, which was a 5HP that got wired right to the pressure switch, but I have not wired a mag starter before. Anyone have any tips on this?

I set everything up for this type unit when I built out the garage - there's 110 volt outlet all set up to power the automatic drain right at the compressor location, and a through the wall drain for the expelled water for the compressor drain.

Any input anyone has on this would be appreciated. Thanks.

 

[Aceman]

The circuit you've installed would work for a 5HP, not a 7.5HP.

 

[Bert_]

The circuit you've installed would work for a 5HP, not a 7.5HP.

#6 sounds fine to me.

NEC says size wire for 40A FLA X 1.25% = 50A rated wire.

#6 NM or #8 THHN

40A breaker is to small though, I'd go with a 60A. NEC allows up to 100A breaker but a 60 is quite a bit cheaper and for a compressor probably won't trip on startup.

Starter wiring is real simple. It will have L1 and L2 on the top side of the starter for you to land your wire on. Everything else will be pre wired.

 

[wyliesdiesels]

I agree with above. #6 is fine.

 

[Dagny]

yep good to go

 

[Cobradriver]

As an FYI....the old building I was in had that exact compressor wired to a 30 amp breaker(not a typo). After ~8 years of use it started popping the breaker on start up. We moved to new location and then the compressor was wired to a 40 and worked fine until I transferred again. I love how Fortune 100 companies can cheap out on the dumbest ****...

 

[767Jockey]

Thank you guys. So If I average out what's being said here. the #6 wire is sufficient. The 40 amp breaker may be too small. No harm in using it to see if it trips or not? As for the hookup, the two hot leads are interchangeable, either one to either terminal on the starter is ok. Sound ok?

 

[sberry]

Sounds ok.

 

[767Jockey]

Just to follow up, I wired and fired it up for the first time today on the 6 gauge wire and 40 amp breaker. I put it through about 20 start cycles. It's happy as a clam on the 40 amp breaker. Thanks for all the info, guys.

This compressor is a beast, by the way. It's brand new and of course the tank was empty. It filled up in about 3 minutes. Pretty impressive performance.

 

[PT Doc]

Just to follow up, I wired and fired it up for the first time today on the 6 gauge wire and 40 amp breaker. I put it through about 20 start cycles. It's happy as a clam on the 40 amp breaker. Thanks for all the info, guys.

This compressor is a beast, by the way. It's brand new and of course the tank was empty. It filled up in about 3 minutes. Pretty impressive performance.

Just curious, what the motor plate states as amps on your motor.

 

[GreyOwl]

Just to follow up, I wired and fired it up for the first time today on the 6 gauge wire and 40 amp breaker. I put it through about 20 start cycles. It's happy as a clam on the 40 amp breaker. Thanks for all the info, guys.

This compressor is a beast, by the way. It's brand new and of course the tank was empty. It filled up in about 3 minutes. Pretty impressive performance.

Did it not require a break in period before actually filling the tank?

 

[767Jockey]

Just curious, what the motor plate states as amps on your motor.

Sorry for the delayed answer, I just saw this. The motor plate says 32.00 amps.

 

[767Jockey]

Did it not require a break in period before actually filling the tank?

I didn't see anything about that in the literature provided with the compressor. Is that commonly done?

 

[alfredeneuman]

Sorry for the delayed answer, I just saw this. The motor plate says 32.00 amps.

Does SPL appear anywhere on the nameplate?
According to NEC, a 7.5hp motor should draw 40A @ 230V.

 

[Bert_]

Does SPL appear anywhere on the nameplate?
According to NEC, a 7.5hp motor should draw 40A @ 230V.

Modern 7.5hp will be around 30 fla. A modern 10 hp is about 40a some are down to 38-39. These are based off baldor, leeson, ect motor with real horse power.

 

[Lonnies Performance]

My 7.5HP Bendpak suggested a 35A breaker, which has been working fine.

 

[wyliesdiesels]

Does SPL appear anywhere on the nameplate?
According to NEC, a 7.5hp motor should draw 40A @ 230V.

~30a FLA is about right for 7.5HP.

The NEC tables are a bit outdated.

there was a discussion on this forum recently about this.