Need some electrical advice

[Egan]

Guys, I've decided to do my own electrical work on my garage addition and I have a couple of questions.

I've done a lot with 120V so I should have no problem wiring up the receptacles and light fixtures. What I'm not 100% certain on is the 240V stuff. I'll have a Rotary 2 post lift and an air compressor in the garage.

From the instruction manual for the lift, it looks like the lift gets 1 black wire, 1 white wire, and 1 green wire. Isn't 240V 2 black wires (2 poles on the breaker) or 1 black and 1 red? I'm pretty sure the same applies for the compressor. Both are single phase, but I'm not 100% certain what that means. I'm assuming the lift gets 2 hots and a ground, without a neutral, but none of my electrical books are clear since they also talk about oven and dryer hookups which are 240V but also carry 120V.

The other question is on breaker sizing. Rotary says to run wire based on 25A size (#10's), but to install a 20A breaker. They said that as long as it is dedicated wiring (it will be) I should have no problems. For the compressor I'm using 5A per HP and figuring at most I'll have 6HP. Does that sound right? I'm probably going to get a 60Gal 12-15CFM compressor. It's just going to do light duty for tools.

For reference, I'm installing a separate subpanel for the garage fed from a spare 70A breaker in my 200A main panel. It will have the 30A compressor breaker, a 20A lift breaker, and two 20A breakers for the receptacles in the garage. The lights will be fed from a spare 15A breaker in the main panel.

 

[Charles (in GA)]

From the instruction manual for the lift, it looks like the lift gets 1 black wire, 1 white wire, and 1 green wire. Isn't 240V 2 black wires (2 poles on the breaker) or 1 black and 1 red? I'm pretty sure the same applies for the compressor. Both are single phase, but I'm not 100% certain what that means. I'm assuming the lift gets 2 hots and a ground, without a neutral, but none of my electrical books are clear since they also talk about oven and dryer hookups which are 240V but also carry 120V.

The other question is on breaker sizing. Rotary says to run wire based on 25A size (#10's), but to install a 20A breaker. They said that as long as it is dedicated wiring (it will be) I should have no problems. For the compressor I'm using 5A per HP and figuring at most I'll have 6HP. Does that sound right? I'm probably going to get a 60Gal 12-15CFM compressor. It's just going to do light duty for tools.

For reference, I'm installing a separate subpanel for the garage fed from a spare 70A breaker in my 200A main panel. It will have the 30A compressor breaker, a 20A lift breaker, and two 20A breakers for the receptacles in the garage. The lights will be fed from a spare 15A breaker in the main panel.

On the lift wiring, go larger than needed. You could probably get away with 12 gauge, but go with 10 gauge and you will be better off. Yes, you would use a red, a black and a bare (ground) wire and no netural on pure 240v. That sounds like what the lift is using. Go buy some 10/2 w/grd and use a red marker to re color the white wire ends to red, its legal, the code says you can re-mark wires that way and are expected to, so the white wire won't be mistaken for a netural.

On the compressor, again, go large. If the run is not long (and thus not real expensive), I'd use #8 or even #6 and you won't regret it later. When in doubt, carry a netural, its possible the compressor may need it for some of the windings in a magnetic starter (but not likely). Again, if you are prewiring for an unknown, you have to allow for all the possibilities.

Depending on how many lights you have and what type they are, you might end up upsizing the lighting breaker to 20 amp, be sure and calculate that load.

Charles

 

[Egan]

Thanks.

The run to the compressor is 33'-35'. For 30A I would normally run #10, but I think I'll take your advice and bump that up to #8 just in case. I'll run a neutral too in case I change to a different compressor or even use it for a welder down the road.

I'm assuming the compressor will come with bare wires instead of a plug. If so, should I use a disconnect box or just a wall mounted j-box of some sort?

 

[bmwpower]

I'm assuming the compressor will come with bare wires instead of a plug. If so, should I use a disconnect box or just a wall mounted j-box of some sort?

The only reason you would need a disconnect is if you could not see the subpanel while standing at the compressor. According to code, you need a disconnect if the breaker is not in plain sight, ie. in another room, floor, etc.

I prefer twist-lock plugs/receptacles, but if you don't ever plan on moving it, a j-box will work, too.

 

[Egan]

The subpanel is outside, so technically, I'll need a disconnect. Does the disconnect need to be fused/breakered? If so, is it just the same size as the breaker in the subpanel?

 

[Stuart in MN]

The local disconnect does not need to be fused. Actually, a receptacle and plug will qualify as a local disconnect, if you want to go that way.

 

[DIGGER_DAVE]

Egan, I don't know if you HAVE done this; but I would STRONGLY recommend you obtain a "Home Owners Electrical PERMIT." After the work is finished; have it inspected.

Many parts of the country (and this includes Canada) now require a permit and inspection. NO permit; NO inspection, COULD void your insurance in the event of an electrical fire.

Better to be SAFE, (and insured) than SORRY!

 

[Egan]

I pulled the permit for the addition myself and that includes everything shown on the plans, including electrical. I'll have the inspector out for (among other things) rough electrical and final electrical.

 

[Egan]

What do you guys think of my lighting layout? 4 of the fixtures in the old garage footprint are existing. I added 2 more to the south for the 9' addition in that direction and a total of 7 for the western addition. These are all 2 bulb 48" fluorescent shop lights. Do you think it is too much or not enough? there will be a lift in the western addition that lines up just south of the door. Ceiling height is 13' in the western section and 8' in the east.

 

[mike944]

If you're doing the wiring yourself, and getting it inspected, one bit of advice is to be extremely neat with your wire runs, and inside your boxes. #1, it shows you've taken the time to do it right, #2 it's easier for the inspector to follow. #3 it's easier for YOU to follow, should you ever have to make repairs, add things, or trace circuits.

If you were an inspector, which one would you scrutinize more carefully, the one that's neat, clean and professional, or the messy-looking rats nest of wires?
________
Suzuki DL650 VStrom

 

[imported_banzaitoyota]

Ditch the 4 footers: GO 8'

 

[Stuart in MN]

I'm actually a fan of 4' fluorescents, if for no other reason than the bulbs are a lot easier to bring home from the store and to install. They also give you a little more flexibility in how you arrange the light fixtures.