Air Compressor wiring

I recently bought a 220v air compressor and am ready to run a plug for it. I have a 200 amp main panel in the house. A 100 amp sub panel in my little shop. I have a 50 amp plug for my welder now and I would like to use the same plug (Noma 6-50R). I don't have a large enough sub panel to add any more breakers so I am looking for a temporary solution till I get the panel upgraded (hence the reason to use the welder outlet for the welder or air compressor). Anyways my question is about bonding. The main panel in the house has the ground and neutral bar as the same thing. If I understand correct this means the panel is bonded?? Everything I read about wiring welders and inductive motors say to only run two hots and a ground. DO NOT HOOK UP THE NEUTRAL. Now if my neutral and ground meet at the same point in the panel it doesn't matter what color the wire is the ground and neutral are the same wire because the originate at the same point in the panel. If I run a #8 ground from the ground bar it is the same as if I take it from the neutral bar. What am I supposed to do?

Btw, it is a 50 amp plug with a 50 amp breaker and #6 wire.

pm sent

Is it a single phase or a three phase?

single phase

Well part of the problem is fixed. I went and bought a larger panel to make room for an extra 30 amp breaker. Still don't understand the neutral/gnd bar on the main panel how ever.

i put a welder plug on my compressor so i could use it for the welder if needed.i'm sure it's just two hot and one ground.i think my 200amp box has some places for big and small ground wire to go.one thing about it tho,if you hook it up wrong it'll let you know!

jasonf wrote:Well part of the problem is fixed. I went and bought a larger panel to make room for an extra 30 amp breaker. Still don't understand the neutral/gnd bar on the main panel how ever.

Neutral/gnd bars are essentially to complete the circuit for 110/120v circuits. With 220/240v it's used as the ground. With 220/240v when one hot wire is negative, then the other is positive, so the two hot wires complete the circuit together because they are "out of phase". This is why 240 volt circuits connect to double pole breakers that are essentially two single pole breakers tied together. In the main panel, every other breaker is out of phase with the adjoining breakers. So, in essence 240 volt wiring is powered by 2 - 120 volt hot wires that are 180 degrees out of phase.

Doug Rahn wrote:

jasonf wrote:Well part of the problem is fixed. I went and bought a larger panel to make room for an extra 30 amp breaker. Still don't understand the neutral/gnd bar on the main panel how ever.

Neutral/gnd bars are essentially to complete the circuit for 110/120v circuits. With 220/240v it's used as the ground. With 220/240v when one hot wire is negative, then the other is positive, so the two hot wires complete the circuit together because they are "out of phase". This is why 240 volt circuits connect to double pole breakers that are essentially two single pole breakers tied together. In the main panel, every other breaker is out of phase with the adjoining breakers. So, in essence 240 volt wiring is powered by 2 - 120 volt hot wires that are 180 degrees out of phase.

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Jason just make sure you don't overload the 100amp sub breaker or the main box with installing to many breakers with the bigger box I would make sure I had the compressor off when welding to be on the safe side to keep from tripping the main if you are using other stuff.

My welder is rated at 44 amps but I never weld anything but small material so I doubt I ever get close to that. The compressor motor is rated at 23 amps. I also have a few other circuits out there for receptacles etc. The odds of everything running at the same time are pretty slim especially since I am not out there every day.

Thanks for everyones help.

jasonf wrote:My welder is rated at 44 amps but I never weld anything but small material so I doubt I ever get close to that. The compressor motor is rated at 23 amps. I also have a few other circuits out there for receptacles etc. The odds of everything running at the same time are pretty slim especially since I am not out there every day. Thanks for everyones help.

There ya have it! I have a Lincoln 225 AC/DC, single phase 120 GA./ 5 HP compressor, lights, two security lights and light (basic amp) receptacles in my 7 bay storage shed and it hasn't burned down yet! Chances of all that drawing on the box at one time is slim. I use #4 wire for all services within the circuit mentioned.

Oh another thing, you'll probably want to move the compressor outside or into another building, they can get noisy!

Dave.

hook it up to the ground bar. if you hook it up to the neutral bar you will be creating a second reference point to ground, (in the compressor) which we try to avoid.
Neutral and ground colors do matter according to code. neutral should always be white, grey, or grey/white. ground green or bare

Dave it purrs along at 800 rpm. It is awesomely quite.

DigginDeeper I used the two hots and a ground.

thx.

800 rpm. What cfm is it.

Mine turns 3100 rpm. but its 27.50 cfm

good job. you are right that it will still work. its just if you have a fault in the compressor you could share that current up the neutrals of the other legs before it reaches the grid.

res0rli9 wrote:800 rpm. What cfm is it.

Mine turns 3100 rpm. but its 27.50 cfm

x2 mine is 20.5 at 90 psi 24.5 at full pressure and it turns 3250rpm with 5hp 220vt