newbie 220 question

[Jason Fastenau]

I'm working on finishing off the electrical in the garage/shop I built last summer. I've pulled two 220 circuits with 4 wires of 8 gauge THHN, (Red, Black, White, and Green), through 3/4 EMT conduit to junction boxes with the longest run being about 65 feet from the box. The thing I'm not sure about is what to do with the green. I get the impression from researching online that the green is primarily there for pulling 110 lines off of the 220, and for certain applications like dryers. Do I just leave it sitting there for regular 220 outlets, or do I tie it in to the metal junction box? I know this is a probably a dumb question, but I'm pretty new at this.

I know the 8 gauge is overkill for what I'll need at the moment, but I figured it's better to overkill once than discover I wish I had more capacity later.

[Scott Dallesasse]

The green is the ground and must be attached to any junction box, outlet box, subpanel and any other metal enclosure for your electrical system. It also must attach to any outlet ground if the enclosure is made from plastic. Also the green is not to be able to derive 110v, that is what the white or neutral is for. The green is to allow the OCPD (a fuse or breaker) to operate in case of a ground fault, either to an enclosure, hot wire directly to ground wire, hot directly to ground or to you. However, this does not mean that you will not feel the effects of a shock, in order to prevent this you should either install a GFCI outlet(s) or GFCI breaker.

Also, be sure to splice in your junction boxes to a smaller gauge as necessary for your 15 and 20 amp receptacles.

What size breaker are you putting the red and black on? This depends on the total constant demand or amps. You really should have a sub panel so if one machine were to overload the circuit, the whole shop wouldn't be shut down.

With the #8 conductors I would keep the constant amp draw, what the equipment attached is using, to 40 amps. This depends on the rating of the terminals of your breaker and of the sub panel if you decide to do this. If the rating is over 60 deg C you could bump that up to 50 amps. To be exact you should consult your local electrical inspector or a local licensed electrician as every state and municipality may have laws and ordinances that affect the national code.

[Jason Fastenau]

Thanks for the reply Scott. I'm actually out in rural Alaska where we have no building codes, inspectors, or thankfully... property tax. Even though I don't need to have it pass inspection I want to wire it like I did since I don't really like the idea of burning down my shop, cabin, and surrounding neighborhood. Plus, if when I eventually sell the place It'll help if everything is done right.

If I understand you right, what I should be doing is attaching the green to the metal junction box when the machine doesn't have a ground wire?

I've got a sub-panel in the shop fed with a 100amp breaker directly off the utility pole. The two 220 circuits will both be running on 20 amp 2 pole breakers for now. I put in the 8 gauge in case I ever needed to increase the capacity to 30 or 40 amps. I figured it would be better to run the wire now, then I could just change out the breaker in the future if I needed more juice.

The smaller 15 and 20 amp receptacles I've got in the shop are running off their own breakers, so I shouldn't ever need to actually pull 110s off the 220.

Every 20 amp 110 circuit except for the lights/garage door has a GFCI as the first outlet in the chain. Do I need to have the 220s on GFCI?