Electrician question..air compressor.

[Steve V]

I just got a IR SSL5 air compressor. I am finding conflicting info all over the net and to specific info in owners manuel. I think I need a 30amp breaker and 10 guage wire,sound good? I have found some say 60amp 6 guage cooper wire. Looks my electrican usde 14 guage 20amp on the circuit so needless to say he's not getting a Christmas card this year. My compressor is across the shop under the stairs from the breaker bo so I will need a separate disconnect at the comp end.

I do not want burn up my new comp or shop. I already wired it and ran it on the under rated setup and it did fine.

 

[Bent6]

A 30A circuit is fine for a 3hp compressor but a 5hp motor would need a 50amp circuit using either #8 THNN stranded or 6/3 Romex.

 

[davelostmissing]

Links would have helped
Compressor, Air, 5.0 HP - Stationary Electric Air Compressors - Air Compressors and Vacuum Pumps - 4YW10 : Grainger Industrial Supply

21.5A
(Edit-better answer above)
Lapp Online Catalog: National Electrical Code Allowable Conductor Ampacity Table 310-16
Voltage Drop Calculator - for single and 3 phase ac systems and dc systems

 

[Rivical]

I'm no expert, as these guys sound to be. But just as comparison... I've an old Speedaire 5hp that I've been using sucessfully since the 80's on #10 THNN, with a 30A disconnect 14" from compressor feed. My current shop's comp location is only about 20' from the panel, but this is the same wire and disconnect I've used on a 30A breaker at up to 60ft from the panel in previous shops.

 

[Steve V]

It is a 5hp model. It is about feet from box.

Thanks for the info.

Sorry about the typos last nite the edit function/or my connection kept messing up when I tried to correct it. It have slow net in the sticks!

 

[TurboBuRick]

Steve,

Read the motor plate. Look for fla. (full load amps) Add 20% to get your breaker size. I didn't get how far of a run but #8 wire should be more than sufficient.

Does the compressor have a motor contact?

RL

 

[Steve V]

Rick what is motor contact? The run is about 30-40 ft from panel after all the logs. I may land up moving it next to the breaker box though.

 

[Steve V]

Talked to the electrician who wired my shop, 12 guage wire he used with 20 amps. He said I need to upgrade to 10guage with 30 amp breaker. I beleive motor was 21.5 amps. I will check tonite.

Since the compressor is fairly quiet and will hardly sun with such a big tank,I may move it next to the panel and run 8 guage just to be safe.

 

[machinegun]

Well based on the AWG amperage ratings for 240 volt check out this chart

How to Size Wiring and Cabling for Your System - AltE

My recommendation would be conduit, THHN #8 on 30 amp breaker. This is of course assuming that like my old compressor using a 5 HP motor with 22 amp start load.

A little overboard but rather be safe and provide as little voltage drop as possible.

You may have to adjust if your run is say more than 15 ft, although with the above combo I think you can go up to 70 feet and be more than with in the AWG ratings.

Hope this helps

 

[Steve V]

Good info..thanks.

 

[TurboBuRick]

Good advice from machinegun.

This is a contact. It's actually called a magnetic motor starter. Motor contact

The bigger hp compressors will usually have one.

RL

 

[davelostmissing]

Contactor?
Contactor - Wikipedia, the free encyclopedia

 

[Steve V]

Again great info and thanks.

It does not have a contactor but it has a reset button on the motor so there something there what I am not quite sure.

FLA is 21.5 so 30 amps will be suffiecent.

I will use 8 guage and am moving right next to the panel. Will be a very short run. 4-5 ft.

 

[TurboV6Olds]

Again great info and thanks.

It does not have a contactor but it has a reset button on the motor so there something there what I am not quite sure.

FLA is 21.5 so 30 amps will be suffiecent.

I will use 8 guage and am moving right next to the panel. Will be a very short run. 4-5 ft.

The reset button is the thermal protection of the motor. All motors need thermal overload protection to avoid damage to the motor. Most smaller motors rated 240 and less have thermal protection in the motor. If you get to motors that are 208v 3 phase or 480 3 phase this is where the magnetic starters come in. A magnetic starter has overload relays in side the starter that can be reset with a push of the button if the motor was overloaded. The purpose of the overcurrent device (Breaker) is to protect the wire used to operate the eqiupment and the overload protection is designed to protect the motor. Good advice from the above posts.
Had to put my two cents worth in, Rick

 

[dynoman]

For that compressor ... simple , 30 amp breaker & 10 ga. wire . no voltage drop to worry about and wire is good to 30a min. 8 gauge wire is a waste of money , harder to work with , and no benefit is gained from using it, the breaker protects the wire. Also that is what is recommended by Ingersol Rand. :wink: Sam

 

[Steve V]

For that compressor ... simple , 30 amp breaker & 10 ga. wire . no voltage drop to worry about and wire is good to 30a min. 8 gauge wire is a waste of money , harder to work with , and no benefit is gained from using it, the breaker protects the wire. Also that is what is recommended by Ingersol Rand. :wink: Sam

I have been all over the book that came with it,the tags on the motor and there was nothing outlined as wire guage and breaker size. But after input on here and research I am satisfied that it will be setup correctly. Guess you have to call IR

 

[dynoman]

Any good electrician would know what size breaker & wire you would need for any given load requirement . In your case it's what I stated. My biggest compressor hook-up was a 1600hp fed with 2300v 3 phase, that was for a compressor at Delco Products. Sam