wyliesdiesels
Well-known member
artieb- u need to run 4 wires to your compressor NOT 3! Neutral and ground CANNOT be the same wire!
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240 vac 7.5hp air compressor voltage drop question
- Thread starter artieb
- Start date
I'm struggling where to connect the neutral in my contactor? I have a L1, L2, and a green that is ground. There is no provision for a neutral. Motor wiring don't need it, and the coil of the contactor only needs 40 ma to the neutral or ground.
I am getting the wire donated, so money is not the issue. If I'm missing something, I'm listening.
I am getting the wire donated, so money is not the issue. If I'm missing something, I'm listening.
nehog
Well-known member
I'm struggling where to connect the neutral in my contactor? I have a L1, L2, and a green that is ground. ...
You don't switch neutral. If you don't have a terminal to land neutral on, you can add one or use a splice or nut.
justsam
Well-known member
You are only going to use the neutral for your 120VAC devices. The contactor coil, and the added relay coil.
Using equipment ground for neutral is not allowed, even for 40mA. Although not at play here GFCI's are designed to trip at 5mA of unbalance between hot and neutral. Equipment ground can not be a current carrying parallel conductor.
Using equipment ground for neutral is not allowed, even for 40mA. Although not at play here GFCI's are designed to trip at 5mA of unbalance between hot and neutral. Equipment ground can not be a current carrying parallel conductor.
sberry
Banned
Changing controls strikes again, changing the simple way it was designed rears its head.
sberry
Banned
If we looked real close I bet the thing even falls under a legal install with 8 cable? We do have a tag where we do know the load. A real 7.5 would need a 6.
But,,, I wuz waiting till we got around to the whole point of this scheme anyway,, to bootleg a control on an existing circuit.
But,,, I wuz waiting till we got around to the whole point of this scheme anyway,, to bootleg a control on an existing circuit.
justsam
Well-known member
Changing controls strikes again, changing the simple way it was designed rears its head.
I somewhat agree although I too have left my compressor ON and with small distribution leaks is does come on once or twice.
For simplicity I wonder why the original contactor was not a 240VC coil?
alfredeneuman
Well-known member
If we looked real close I bet the thing even falls under a legal install with 8 cable? We do have a tag where we do know the load. A real 7.5 would need a 6.
.
The nameplate say 32A. The NEC rates it at 40 & this is the figure you must use for conductors and breakers (at 125%)
A #6 if doing it in N/M, a #8 if in conduit.
.....................................................................................
The coil itself in the starter has 2 terminals
If there's a terminal on coil that doesn't have a jumper wire attached to it the neutral goes there
Last edited:
sberry
Banned
I leave mine on, I got some leaks and never find them, I live with it. I have a backup comp I turn the breaker off but take my chances the way the oem made it with basic code requirements, I don't add disconnects and switches if I don't have to.
As a practical mechanical matter a 10 cable would not cook especially if this unit followed any duty cycle.
Despite its HP claim etc it makes a pretty respectable amount of air and unless the OP is blasting with it the thing probably doesn't run much. It will run a body tool with room to spare.
True "efficiency" or noticeable loss from underwire is a rather minor concern again unless this is a production operation, hrs per day vs a few minutes.
As a practical mechanical matter a 10 cable would not cook especially if this unit followed any duty cycle.
Despite its HP claim etc it makes a pretty respectable amount of air and unless the OP is blasting with it the thing probably doesn't run much. It will run a body tool with room to spare.
True "efficiency" or noticeable loss from underwire is a rather minor concern again unless this is a production operation, hrs per day vs a few minutes.