Electrical lable and wiring for compressor

[gs8212]

I'm plannning the wiring of my existing basic homeowner attached garage to add workbench receptacles and overhead general lighting. I've been scouring the electrical subforum and learned a lot. The basic questions about circuit loads etc. drove me to one specific question which is the topic of this thread.

The question is about interpreting the compressor electrical label and using that to determine some of the circuit wiring specs.

Here is the label on an IR compressor; small homeowner model.

[ATTACH]415413._xfImport[/ATTACH]

Based purely on the label information I've done a few calcs as follows to see whether I've understood some of the basics.

2hp motor x 746 watts per = 1,496 watts or the approx 1.5 KW.

115 v x 15 amps = 1,725 watts. I guess they're telling me with this info that a 120 volt 15 amp circut is minimum need.

However, since the needed 1,496 watts calculated above is already about 82% of the watts of a 120 v 15 amp circuit, is the conclusion then that I need a dedicated 15 amp circuit with a single receptacle for this plugin compressor? I'll start a different thread on the question of how many other working circuits and receptacles I should plan for the garage.

Thanks much.

 

[dw1]

You can get by with running # 12 (12/2 w/gr romex) and putting this in a 20 amp breaker.

YOur compressor draws 15 amps at 115 volts, a 15 amp circuit will not hold

 

[sberry]

Yes, those are notorious, Run a 12 wire to a single outlet for it, only thing on this circuit, no lights, no splices etc.

 

[gs8212]

Thanks dw1 and sberry. Is it "technically" within code to run the compressor on a 15 amp circuit, but just not the best practice? I've gotten the impression code is minimum but best practice might be something entirely different.

 

[Bondo]

Thanks dw1 and sberry. Is it "technically" within code to run the compressor on a 15 amp circuit, but just not the best practice? I've gotten the impression code is minimum but best practice might be something entirely different.

Ayuh,... Yer gonna want 20a outlets, as it's a Workshop,...

Wire 'em All as 20a outlets, 'n you can plug yer compressor into any one of 'em you'd like,....

 

[gs8212]

Ayuh,... Yer gonna want 20a outlets, as it's a Workshop,...

Wire 'em All as 20a outlets

I agree. thanks. How do I tell if I'm bumping up against the capacity of my breaker box? I finished the basement and had it inspected but did add a lot of circuits (full bath, bar and small fridge, lights, etc.) so with the garage I'm wondering about capacity.

 

[pattenp]

Add up the amps of everything you think typically will be running at the same time and compare that to the main breaker serving that panel. Use 100% of the non-continuous and 125% of the continuous loads.

 

[sberry]

Thanks dw1 and sberry. Is it "technically" within code to run the compressor on a 15 amp circuit, but just not the best practice? I've gotten the impression code is minimum but best practice might be something entirely different.

It could run from a 15 and in some cases smaller wire may help with preventing trips. The factory cord is usually 15 with a 15 end and you really don't have any use for true 20A recepts. They really are for institutional use usually with floor equipment or some place needs a dedicated circuit to keep specialized machines off of general use circuits.

 

[sberry]

With about 50 ft of 14 wire it might work. With 5 or 10 ft of 12 on a sturdy service they will trip a 20 as will a chop saw. I had one on a 16 wire that would trip a 20 after a half a dozen starts. I had free wire and used a 10 for it but in hindsight would have used a 12,,, its never tripped a 30.

 

[dw1]

I would say on a 15 amp circuit breaker that you would have a good chance of tripping the CB when the compressor started. I have aCraftsman Air Compressor (it draws 15 amps), I wired it on its own 20 amp circuit and never had any problems out of it

 

[dw1]

if you are adding lighting circuits in your garage, wire them in 14/2 romex and use 15 amp circuits, I would wire all the plugs in 12/2 and on 20 amp circuits, you will be just fine!!

 

[gs8212]

Sorry for the late response guys. Thanks to all of you for the insight. Got sidetracked on cabinet install and expanding lighting on the existing 15 amp cicuit. Plan to add 20 amp circuits for compressor and workbench outlets.