HF 60gal compressor wiring question.

[EvilBean42]

So I've been creeping on this forum for years and would like to start by thanking the community for all the help I've gotten just by reading in the past. Currently I'm setting up a very small commercial auto repair garage and have been referring to these forums even more than usual. I just picked up the HF 60 gal compressor as the reviews on here were pretty great. Problem is it calls for a 40A circuit in the manual. I have a 30A outlet right next to the unit and planned on running a 2' Cable to it. I can't figure out why it would need a 40A breaker based on the rest of the specs in the manual. My uncle has been running one on a 30A breaker for years without a problem. For those of you that own one, how do you have it wired up? I have the Central Pneumatic branded one, not the old US General one if that makes a difference.

 

[md21722]

Wiring the compressor to code requires #8 Nm-b (Romex) or #10 THHN in conduit. Also plugs are not allowed. A 30A breaker should work fine.

 

[sberry]

The above is correct but I wouldn't lose any sleep with one wired to a 10/30 cable for this class of comp and some of them been using special motors to get around this code issue. No one ever burned down the garage with this.

 

[EvilBean42]

I know it's not supposed to have a plug, but the real goal here (which I should have explained in the original post) is that I'd like to be able to share the circuit with my wheel balancer so I don't have to run a second 230 line. The balancer uses a 30a turnlok plug. The outlet is run with 10ga armored Cable, it's less than 2' from the breaker box. My real concern was That even though the manual says full load amp draw is 23 that maybe for just a fraction of a second it could hit 30+ when it starts and that would be why they require a 40a breaker.

 

[sberry]

It could use a 50 breaker. Back in the day had one with 18A run on a 20 but it was on old Fed panel and was never really sure of it and in hindsight ,, who knows but used a 40 for a welder too, they were pretty sturdy.
From actual experience and a lot of it before I knew any better or different,,,,,,,,,,,,,,,,,,, I have seen several heavier comps real 5 that run on 30A fore decades. I am not sure how many have caused trips, I never saw one unless the motor had a problem.
I have a 23 or 24 A and its on a 30 on a comp (got one on pressure washer too) but comp specific and never tripped it. I now have my 3 hp (18 run) on a 30, back when it was on a 20 the service wasn't so sturdy but its close to the panel and delivery isn't an issue, never tried a 20 there but my well which is 15 had tripped on rare occasion and never sure why but up it also to 30.
I suspect the comp on a 20 so close to the panel it may trip once in a while. I did come in to no air, had a cap fault and had tripped it like it should. So,,, the moral of this story is I am with the gang running closer to the threshold if it handles it and use a 30 unless there is better reason not to. With tight belts may even fault in the event of mechanical problem within comp itself.

 

[sberry]

My 3 is on a plug and my 5 is too keeping in mind I do this at my own risk, the breaker is off, never use it but there for backup or some blasting demand, both very rare. We would probably be violating the working room to panel here a bit, I actually removed the blue spare a while back to work behind it. All the vessels are double valved but normally open. Both feed the receiver then to the manifold and all plumbed to a common drain with simple valves.

 

[md21722]

Circuit breakers are designed to allow the inrush current of a motor starting. 5HP motors use 120A-170A on startup. I have had several 5 HP and all work(ed) fine on 30A breakers. By code you can use up to 70A if its hardwired and everything else is right.

 

[sberry]

I really like the 3.5 hp class (small 5) or real 3 hp like mine. They are a little short for body work, with extra cap in storage I am really finished with jobs before air is a problem or I pick up and get straight or move while its pumping but its rare. A true 5 is a lot better for body but the 3 is so kind to my electric, runs longer with big tanks but fewer cycles.
Got a champ R-15 on it, been on since about 1972 or so and I replaced a rod bearing and rings on one cyl a long time ago, way pre internet.

 

[EvilBean42]

Ok, I think I feel pretty comfortable with using a 30a circuit at this point. Thank you all very much for the input. I'm excited to be a part of this community after years of watching from the sidelines.

 

[redmondjp]

Just don't operate the wheel balancer when the compressor is running! Now if you are planning on sharing one receptacle and swapping plugs between the two machines, that will wear out your receptacle eventually (the spring contacts inside will not grab as tightly over time, causing higher contact resistance and more heat generation).

 

[71firebird400]

As an electrical engineer I'd look at the full load amps of the unit (22A), multiply by 1.25 (per NEC 430.122(A)) to determine the conductor size, which results in 27.5A (#10 AWG). The short-circuit protection (NEC 430.52) has a degree of flexibility being that this is a motor circuit (and I'm ignoring the fact you have a plug on it) but the 30A breaker should be fine. If you do have a problem with it you could hardwire it, bump up to a 40A breaker and be in full compliance with the code. Running the compressor with the 30A breaker will definitely not hurt anything, the only thing you risk is the occasional nuisance trip.

 

[EvilBean42]

I am planning on sharing one receptacle so I can't run both at the same time. I don't think I should have too much trouble with wearing it out because the wheel balancer won't be used more than once a day and the shop I'm in is a temporary location. I am starting in a tiny shop to keep costs down while I build a customer base, and will hopefully move to a larger location where I can set things up properly within a year.

 

[md21722]

As an electrical engineer I'd look at the full load amps of the unit (22A), multiply by 1.25 (per NEC 430.122(A)) to determine the conductor size, which results in 27.5A (#10 AWG). The short-circuit protection (NEC 430.52) has a degree of flexibility being that this is a motor circuit (and I'm ignoring the fact you have a plug on it) but the 30A breaker should be fine. If you do have a problem with it you could hardwire it, bump up to a 40A breaker and be in full compliance with the code. Running the compressor with the 30A breaker will definitely not hurt anything, the only thing you risk is the occasional nuisance trip.

The only problem with this is that it's not code. The NEC has rules for motor circuits. You take the motor horsepower off nameplate, and look up the FLC in the NEC tables, multiply by 125% and wire size to match. In this instance, it's 5HP so 28A per NEC tables X 125% = 35A = #10 THHN in conduit or #8 NM-b (Romex).

As sberry says, there are many, many people who see 23A on nameplate, and run a standard 30A electric clothes drier circuit.. and I've never heard of someone burning down their house from doing so.

 

[Roberts210]

There is no need to pay attention to any stinkin' codes. They're baloney anyway.

This is from my friends' house that burned because the mex. roofing contractors were running their compressor out of a lighting socket in the attic. Something apparently overheated, the "ecologically pure" cellulose blown-in insulation caught fire and burned the entire attic and roof. Then the FD pumped water into the house for 45 minutes. Contractors said it wasn't their fault. FD investigators said any evidence burned up in the fire. The owners were left holding the bag.

 

[md21722]

It's a bum deal that your friend's house burned down. But it wasn't caused by the codes or the contractors. A poor or loose connection can create excessive heat and start a fire. I have seen extension cords too hot to touch and several inches of a neutral wire with melted inside the panel. Had it ran long enough no telling what would've happened. The cause, a loose neutral for that circuit at the panel. Everything else was correct.

 

[sberry]

Yes, different case. I try not to load general's to smoke if I can help it. My ideal to heavy draw items is breaker/wire/recept. One device with no splices.

 

[sberry]

Who the fukk would turn a crew of Mexican roofers loose in their attic???
There was a case of customer/contractor being a perfect match.

 

[Roberts210]

It's a bum deal that your friend's house burned down. But it wasn't caused by the codes.

Perhaps my sarcasm about the wisdom of following the Building Codes should have been laid on a little heavier.

Codes are there for safety.
Obviously the roofing contractors violated some basic laws of safety.

And YES, IT WAS MOST DEFINITELY CAUSED BY THE ROOFING CONTRACTORS. The fire happened in the afternoon while the mex roofing contractors were merrily running their compressor on a very, very long, relatively small gauge extension cord. They had plugged it into a lighting socket, in the attic, right on top of the (flammable) cellulose insulation. According to the arson investigator fire started within a few feet of where their compressor had been plugged in.

 

[Roberts210]

Who the fukk would turn a crew of Mexican roofers loose in their attic???
There was a case of customer/contractor being a perfect match.

That my friend, is ALL THAT IS AVAILABLE IN LOS ANGELES. And soon coming to a neighborhood near you if immigration patterns continue. They were licensed and bonded. But of course they claim they din do nuthin'.

 

[sberry]

So your bud doesn't have power available, doesn't watch a bunch of dumb fuks booger a comp on to a circuit. What kind of code may prevent this?
I do understand, **** happens, we try to keep it to a minimum.

 

[Roberts210]

So your bud doesn't have power available, doesn't watch a bunch of dumb fuks booger a comp on to a circuit. What kind of code may prevent this?...............

It wasn't the owners job to supervise--he was at work, and the wife doesn't know anything about building. The 2 and 4 year old daughters sure didn't know anything. That's why people hire things done. I'd been working on the house in the weeks previously but on the day of the fire I'd gone to pick up materials and tools. I didn't get back until the fire trucks were there.

The owner has a real job and needs to be at work. The (licensed and bonded) roofers are the ones to blame. In order to get into the attic, which was only 4 feet tall at it's tallest point you had to get a ladder and climb through a hole in the dining room ceiling. Going into the attic was not something they ever did. Nothing was ever stored up there. I only found out about the elec. cord the next day, after the fire, when we took a look around. Earlier in the job the roofers had their compressor plugged into a 20 amp receptacle on the first floor. Once they tore the old roof off, they accessed the elec. light from above.

 

[redmondjp]

It wasn't the owners job to supervise--he was at work, and the wife doesn't know anything about building. The 2 and 4 year old daughters sure didn't know anything. That's why people hire things done. I'd been working on the house in the weeks previously but on the day of the fire I'd gone to pick up materials and tools. I didn't get back until the fire trucks were there.

The owner has a real job and needs to be at work. The (licensed and bonded) roofers are the ones to blame. In order to get into the attic, which was only 4 feet tall at it's tallest point you had to get a ladder and climb through a hole in the dining room ceiling. Going into the attic was not something they ever did. Nothing was ever stored up there. I only found out about the elec. cord the next day, after the fire, when we took a look around. Earlier in the job the roofers had their compressor plugged into a 20 amp receptacle on the first floor. Once they tore the old roof off, they accessed the elec. light from above.

I live in the Seattle area, and it's no different here. I've taken days off to watch contractors (top-rated ones, using Angies' list and so on) work on my house, and it's just plain scary. Example: my roofers had a new guy on the crew - his solution to bubbles in the tar paper, since they didn't lay it down flat, was to take a utility knife and go all Friday the 13th on it. If I ever have roof leaks in that part of the garage, I'll know why.

This is why I try to do all of my own work, as much as possible. The 'pros' also undersized the air return to my gas furnace by 50%, which could explain why I've gone through three furnaces in the past 15 years. I added my own second return when I installed furnace #4.