[bluesman2333]

Just L1, L2 and the ground are sufficient. These will be the wires from a two pole breaker and the ground bus in the panel. If you are running romex, you will have a black white and bare wire. Relabel the white wire with red tape, it will be a hot not a ground in your circuit. If you run EMT or other raceway, pull a black, red and green in the pipe.

[scotzz]

Originally Posted by bluesman2333

Just L1, L2 and the ground are sufficient. These will be the wires from a two pole breaker and the ground bus in the panel. If you are running romex, you will have a black white and bare wire. Relabel the white wire with red tape, it will be a hot not a ground in your circuit. If you run EMT or other raceway, pull a black, red and green in the pipe.

bluesman2333....that's what I thought........thanks

Another question: I am running a line from the current dryer 240V outlet out to the garage. The dryer outlet is on a separate line and has a subpanel with two 20V breakers just above the outlet. The line to the garage is going to be basically an extension and not hardwired into the circuit. I will unplug the dryer and plug in the extension line. The dryer circuit is on 12 gage wire (or at least it should be). Since the extension line to the garage is about 55 feet, should I run 10 gage or stick with 12 gage?

Also, there should be no difference in wiring for a dryer other than it may have a neutral wire included........correct?

[ztoy]

At 55 feet

Your dryer circuit is probably a 240v 30 amp circuit which should be fine for your compressor as well. #10 copper wire will be fine.

[302 Z28]

Originally Posted by bluesman2333

Just L1, L2 and the ground are sufficient. These will be the wires from a two pole breaker and the ground bus in the panel. If you are running romex, you will have a black white and bare wire. Relabel the white wire with red tape, it will be a hot not a ground in your circuit. If you run EMT or other raceway, pull a black, red and green in the pipe.

I might add, according to NEC re-label both ends of that white wire now that it will be a hot.

Vince

[roger1]

For a 15 amp compressor use a 2 pole 20 amp breaker and 12-2 w/ground Romex. If it was a long distance run, then go to 10-2.

Anything more is overkill and using a 30 amp breaker is the wrong thing to do.

[bluesman2333]

The circuit breaker size is only loosely associated with the load. The wire size for a motor load starting a compressor could be heavier than a #10 for a 30 amp circuit. #10 might be fine for a dryer but you might need #8 or possibly #6 depending on the distance and the load, ie if the compressor starts hard.

A good rule of thumb is to take 125% of the running amps then look at what circuit breakers would be suitable, at 80%. So, a 20 amp compressor would be 25 amps for calculation sake and a 30 amp breaker would be 24 amps so a 40 amp breaker with a minimum of #8 would be used.

[roger1]

Originally Posted by scotzz

The dryer circuit is on 12 gage wire (or at least it should be).
Also, there should be no difference in wiring for a dryer other than it may have a neutral wire included........correct?

A dryer circuit should be on 10 gauge wire.
Old code would be 10-2 w/ground and new code is 10-3 w/ground.

[scotzz]

Originally Posted by roger1

A dryer circuit should be on 10 gauge wire.
Old code would be 10-2 w/ground and new code is 10-3 w/ground.

Yes.......you are right.......the dryer circuit is 10 ga wire with a 30 amp double pole breaker. Using 10-2 w/ground wire ............does the neutral pin on the plug get wired to the ground?

[roger1]

Originally Posted by scotzz

Yes.......you are right.......the dryer circuit is 10 ga wire with a 30 amp double pole breaker. Using 10-2 w/ground wire ............does the neutral pin on the plug get wired to the ground?

No it does not. In the case of a dryer using 10-2 wire, a neutral is not used.

Where 10-2 wire was used (old code) the receptacle and plug should be 3 prongs. In new installations (10-3 wire) a 4 prong receptacle and plug are used. You shouldn't install a 4 prong receptacle when 10-2 wire is used. (It would work, but it's the wrong thing to do.)
If you have a 3 prong receptacle and a 4 prong plug on a new dryer, your dryer cord should be changed to a matching 3 prong plug. Your big box hardware stores will carry the cords.

[scotzz]

Originally Posted by roger1

No it does not. In the case of a dryer using 10-2 wire, a neutral is not used.

Where 10-2 wire was used (old code) the receptacle and plug should be 3 prongs. In new installations (10-3 wire) a 4 prong receptacle and plug are used. You shouldn't install a 4 prong receptacle when 10-2 wire is used. (It would work, but it's the wrong thing to do.)
If you have a 3 prong receptacle and a 4 prong plug on a new dryer, your dryer cord should be changed to a matching 3 prong plug. Your big box hardware stores will carry the cords.

The outlet I installed in the garage is a 3-prong, 50A, 250V (6-50R). The directions say the third pin is ground. I wired this pin to the neutral wire and it seems to work fine.

[bluesman2333]

In a residential install, the neutral will be ground. You need to tape it green and re-land it to the ground bus if there is one. With this outlet, you need to run a minimum of #8, so the dryer circuit wiring will be too light if that's what you used.

[scotzz]

Originally Posted by bluesman2333

In a residential install, the neutral will be ground. You need to tape it green and re-land it to the ground bus if there is one. With this outlet, you need to run a minimum of #8, so the dryer circuit wiring will be too light if that's what you used.

Why do I have to use #8?

[timothale]

My son is and electrical contractor- and master electrician. Now I ask him what are the new rules in the 'NEC. As stated in previous posts wire size depends on the wire distance from the breaker to the load and overload calculation... An electric dryer has 110 volt control-timer and the rotation motor is 110 volts which doesn't have and much starting power requiremenrts

[bluesman2333]

The maximum wire size is governed by one of three things. 1) If the load is a motor load like a compressor which has a high current start out of proportion to the running current, 2) the distance between the circuit breaker and the load causes voltage drop, or 3) if you have a certain plug configuration as is your case. A 10 gauge wire will not support a 50 amp circuit.

You need to install the correct sized wire and circuit breaker.

[roger1]

Originally Posted by scotzz

Why do I have to use #8?

You say you installed a 50Amp outlet.
That may be the wrong one for your dryer.

I have never seen an electric residential dryer that wasn't 30 Amps.

50 Amp will require #8 and 30 Amp requires #10.