Can you be limited to a certain number of amps?

[The motor guy]

Is there a limit to the number of amps that can be run through a single phase 240v line? I'm going to buy an industrial grade 80 gallon quincy air compressor and it looks like it calls for a 80 amp breaker and pulls 40 amps when running. It's going to make a 100ft run from the breaker box, along with running a few other things.

 

[The motor guy]

I'd prefer to have most of these tools purchased so he can wire them up, but I don't want to buy them and then have the electrician say it can't be done.

 

[spasm3]

Even #6 wire is probably only rated for 30 amps or so on a 100ft run. You may need a line from the power company closer, so you have a shorter run from a breaker box.

 

[ondarvr]

The wire is sized to the load and length of the run. It is limited by the existing panel and your wallet.

 

[meadows]

Have the power co. drop another line to your building. My neighbor has 3 drops to his house. Big house.

 

[Donald]

Where is the circuit breaker box? Where is the compressor going? Is this a house or shop?

I would be inclined to get a 100 amp branch box installed in the general area of the compressor.

If a home do you need that large a motor? A 5 HP 60 gallon two stage should be enough for any home.

If a shop maybe consider 3 phase if available?

 

[Ws6]

My 1 gallon portable air compressor that I use solely to remove my eXmark blades seems wholly inadequate reading OP, lol!

 

[Skippy722]

Originally Posted by Ws6
My 1 gallon portable air compressor that I use solely to remove my eXmark blades seems wholly inadequate reading OP, lol!


I have one like this, except it's a craftsman from the 80's!

When they asked OP how much air he wanted to move, he must have answered "all of it!"

 

[ctechbob]

That seems like an awfully high current draw for an 80 gallon compressor. You sure about those specs?

 

[clinebarger]

40 amps single phase constant is like 10 horsepower.....Generally used on 120 gallon compressors. 7.5HP on a 80 Gallon with a 2-stage pump is more than enough!

Are you going to be media blasting on a commercial level or something? If so......It would be wise to have a dedicated 3 phase service installed.

It's tough to take you seriously at times Madman!

 

[Wolf359]

Well an 80 amp breaker is going to need 3 gauge wire. The 4 wire is $6.72 a foot at Home Depot so at 100 feet about $672 in wire alone plus cost of the electrician and breaker. But that's a pretty impressive compressor. There are cheaper models if you don't need that kind of CFM and a 50 amp breaker would only need 6 gauge wire which would be about half the cost.

https://www.northerntool.com/shop/tools/product_200350477_200350477

https://www.homedepot.com/p/Southwi...Stranded-CU-SER-Cable-27757499/205001797

https://www.homedepot.com/p/Southwi...pull-CU-NM-B-W-G-Wire-63950002/202316279

 

[dlundblad]

You just need this heavy wire because of the distance or it actually does require if?

I have a 5 horse 60 gallon compressor that needs 32ish amps to start. It's only 30' from my sub panel though.

 

[uc50ic4more]

Limited number of amps? *Never*.

 

[spasm3]

 

[Wolf359]

Originally Posted by dlundblad
You just need this heavy wire because of the distance or it actually does require if?

I have a 5 horse 60 gallon compressor that needs 32ish amps to start. It's only 30' from my sub panel though.


For an 80 amp breaker, that's the requirement of the breaker. The distance isn't that crazy. Normally I think you can go up to 200 feet from the panel and you're not supposed to draw more than 75-80% of the rated load anyway so if it's drawing just 40 amps out of an 80 amp outlet, it should be fine.

 

[The motor guy]

80 amps is the startup load. 40 is the running amperage. I can get an 80 gallon with a smaller motor that only draws 28 amps. I think that one requires a 50 amp breaker.

 

[exranger06]

Originally Posted by Wolf359
Well an 80 amp breaker is going to need 3 gauge wire.

Wrong. Motor circuits are wired differently. You're allowed to use a breaker that would normally be way too high for the wire size. I have #10 wire for my 60 gallon compressor and it's on a 40 amp breaker. I could go up to a 70A breaker if I wanted to and keep the #10 wire. Read article 430 of the NEC. For a motor circuit, the breaker is only there to protect against a dead-short to ground. The motor has it's own built-in thermal overload breaker to protect against overloads due to motor malfunction. And you're allowed to use a high-amperage breaker so the high start-up current doesn't cause a nuisance trip.

OP, in order to tell you which size wire and breaker you need, we need to know the HP rating of the motor. It is literally impossible to tell you which materials you need without that spec. Like I said, for motor circuits, you need to follow Article 430 of the NEC. All of the wire sizes and breaker sizes are based off of the HP rating of the motor; all other specs are basically irrelevant.

 

[Wolf359]

Originally Posted by exranger06
Originally Posted by Wolf359
Well an 80 amp breaker is going to need 3 gauge wire.

Wrong. Motor circuits are wired differently. You're allowed to use a breaker that would normally be way too high for the wire size. I have #10 wire for my 60 gallon compressor and it's on a 40 amp breaker. I could go up to a 70A breaker if I wanted to and keep the #10 wire. Read article 430 of the NEC. For a motor circuit, the breaker is only there to protect against a dead-short to ground. The motor has it's own built-in thermal overload breaker to protect against overloads due to motor malfunction. And you're allowed to use a high-amperage breaker so the high start-up current doesn't cause a nuisance trip.

OP, in order to tell you which size wire and breaker you need, we need to know the HP rating of the motor. It is literally impossible to tell you which materials you need without that spec. Like I said, for motor circuits, you need to follow Article 430 of the NEC. All of the wire sizes and breaker sizes are based off of the HP rating of the motor; all other specs are basically irrelevant.


I believe he said he was also going to use that outlet for other things too.

 

[exranger06]

Originally Posted by Wolf359
Originally Posted by exranger06
Originally Posted by Wolf359
Well an 80 amp breaker is going to need 3 gauge wire.

Wrong. Motor circuits are wired differently. You're allowed to use a breaker that would normally be way too high for the wire size. I have #10 wire for my 60 gallon compressor and it's on a 40 amp breaker. I could go up to a 70A breaker if I wanted to and keep the #10 wire. Read article 430 of the NEC. For a motor circuit, the breaker is only there to protect against a dead-short to ground. The motor has it's own built-in thermal overload breaker to protect against overloads due to motor malfunction. And you're allowed to use a high-amperage breaker so the high start-up current doesn't cause a nuisance trip.

OP, in order to tell you which size wire and breaker you need, we need to know the HP rating of the motor. It is literally impossible to tell you which materials you need without that spec. Like I said, for motor circuits, you need to follow Article 430 of the NEC. All of the wire sizes and breaker sizes are based off of the HP rating of the motor; all other specs are basically irrelevant.


I believe he said he was also going to use that outlet for other things too.

The compressor needs its own dedicated circuit. You can't put receptacles or "other things" on that circuit. He'll have to either run an additional circuit(s) for the other stuff, or install a subpanel in that area and run a single feed to it. The circuit from the subpanel to the compressor will still follow Article 430.

 

[Wolf359]

Originally Posted by exranger06
Originally Posted by Wolf359
Originally Posted by exranger06
Originally Posted by Wolf359
Well an 80 amp breaker is going to need 3 gauge wire.

Wrong. Motor circuits are wired differently. You're allowed to use a breaker that would normally be way too high for the wire size. I have #10 wire for my 60 gallon compressor and it's on a 40 amp breaker. I could go up to a 70A breaker if I wanted to and keep the #10 wire. Read article 430 of the NEC. For a motor circuit, the breaker is only there to protect against a dead-short to ground. The motor has it's own built-in thermal overload breaker to protect against overloads due to motor malfunction. And you're allowed to use a high-amperage breaker so the high start-up current doesn't cause a nuisance trip.

OP, in order to tell you which size wire and breaker you need, we need to know the HP rating of the motor. It is literally impossible to tell you which materials you need without that spec. Like I said, for motor circuits, you need to follow Article 430 of the NEC. All of the wire sizes and breaker sizes are based off of the HP rating of the motor; all other specs are basically irrelevant.


I believe he said he was also going to use that outlet for other things too.

The compressor needs its own dedicated circuit. You can't put receptacles or "other things" on that circuit. He'll have to either run an additional circuit(s) for the other stuff, or install a subpanel in that area and run a single feed to it. The circuit from the subpanel to the compressor will still follow Article 430.


Yeah, that was a little strange. But I think technically you could plug in other things that may run closer to 80 amps. I had a friend with wood working equipment in his basement that he would move around so OP didn't mention what other stuff he might want to plug in.

I was thinking you could just get away with a 50 amp breaker if it just calls for 40. According to the manual it's just 40 amps. And 7.5 horsepower converts to about 23 amps at 240 so that 40 amps might be the peak and not 80.