Another Electrical Question
 

I want to put a subpanel in my garage. Off of the subpanel, I want two circuits.

1) 15 amp circuit for some standard electrical sockets.

2) One 240v circuit to power this air compressor:

http://forums.pelicanparts.com/uploa...1554857169.jpg[/QUOTE]

Questions:

1) What amperage should I make the breaker in the main panel that leads to the subpanel?

2) What gauge wiring should I use from the breaker in the main panel to the subpanel?

3) What amperage should I make the main breaker in the subpanel? I assume it should be the same as #1.

4) What amperage should I make the breaker for the 240v air compressor circuit?

5) What gauge should I make the wiring from the breaker for the air compressor circuit to the socket for the air compressor?

6) What type of sockect (and pigtail) should I use for the air compressor?

Why not just pull a few wires from the main panel into the garage? Two 20A circuits for plugs and one 30A circuit for the compressor. 10/3 w ground for the compressor and 12/2 w ground for the plugs.
For pig tail I'd go hot to the compressor meaning wire from your main panel to the compressor at a J box.

Strike that! You're only 7.5 FLA to at 240V so a 15a 240v circuit should be fine. Must be a small compressor? There are wire sizing calculators for length of run. You just want to make sure your breaker is sized for the wire so you don't have a breaker size greater than the amperage the wire is rated at for the length of run.

Is there a reason you do not want to run this on 110v? How far is the main panel from the one you want to put in? Only one extra circuit, could also consider adding a 120v 20A circuit. Does your main panel have extra space available?

I like the subpanel idea better.

I'd use 4x #6 wire to the subpanel up to 50' run and a 50A breaker at the main. I'd run #12 wire for the plugs and compressor with 1x 115v 20A breaker and 1x230v 20A breaker. This way you have enough wire to run power tools on your outlets and reserve capacity on your 230v circuit and your panel for the future. Pretty standard stuff.

Couple question before I jump the gun.

How far is the garage from the main panel? You need to be mindful of voltage drop over vast distance between the two panels.

How big is your main panel? 200? If so, a 60 amp sub panel should be more then enough for the garage unless you have one of those monster garages and run all kinds of electrical items from it. Future HVAC plan or already in place?

Normally a #6 wire should do, depending on the distance. If its near 100' then I would suggest a 4 gauge wire

From your sub panel, run #12 for all your 120v plugs. Same wire for your 220 that goes to your compressor. Max draw is only 7.5A

Questions:

1) What amperage should I make the breaker in the main panel that leads to the subpanel? Minimum 40A, but the standard would be 50A

2) What gauge wiring should I use from the breaker in the main panel to the subpanel?
6 gauge

3) What amperage should I make the main breaker in the subpanel? I assume it should be the same as #1. Yes, 40AMP minimum, but 50A would be more normal. They should match

4) What amperage should I make the breaker for the 240v air compressor circuit? 2.5* the rated amps, rounded to next highest. This will be 20 Amps

5) What gauge should I make the wiring from the breaker for the air compressor circuit to the socket for the air compressor? At 240VAC/20 Amps you will need to run 4 wires, For a motor, 10 gauge would be recommended

6) What type of socket (and pigtail) should I use for the air compressor? There are many. A NEMA L14-20P & L1420R will probably work well

Leave the compressor on 220. Put in a 40 or 50 Amp sub-panel.

Do it once, do it right.

The spot in the garage where I want to put the subpanel is about 20 feet from the main panel, though the run will be longer.

Anyone else think it's weird that LRA isn't listed on that motor? I don't pay much attention anymore but do they not list that?

To what RB wrote, I'd probably put a star next to that 6 gauge wire from the panel to the sub panel simply because I don't think the OP listed the length of wire that will be run from the main to the sub. I'd also add that it depends on whether you're using copper or aluminum strand wire.

Strike that! Just saw OP's last post. 20' of length. 6 gauge would be sufficient. You could go to 4 gauge aluminum which probably won't cost a lot more and put a 50 amp breaker on that.

This is very concise. ^^^^ If you run 10 gauge wire for the 240v 20 amp circuit, you can always upgrade to 30 amps later without rewiring. 50 Amps on 6 gauge wire ran my shop for years. You can use Aluminum for the 6 gauge.

I went to all four hardware stores in town today: Menard's, Lowe's, Home Depot, and Ace. None stock 50 amp subpanels. I see 50 amp RV panels and hot tub panels, but those aren't really the right things. I really only see 70 amp subpanels like this:

https://www.menards.com/main/electrical/circuit-protection-distribution/main-lugs/square-d-trade-homeline-trade-70-amp-2-space-4-circuit-indoor-residential-main-lugs/hom24l70s/p-1444444040087-c-6438.htm

I assume that if I were to use something like this, I'd have to have a 70-amp breaker in the main panel and it might change the wiring requirements to the subpanel.

Breaker size is determined by wire size, and wire size is determined by load and run distance. The 70A panel will be fine and you can then outfit it as you wish. With 2 20A circuits in the garage, #6 wire from main to sub and a 50A breaker will be fine. If you wish to have a full 70A capacity in your garage run #4 wire and a 70A breaker. This should help:
https://www.askmediy.com/subpanel-installation/

I suggest not to mess around with those and get one with more slots. You never know what you will need later. Pay a few bucks more, but the install is the same.

Look up 60 A (50 if you like) sub panel with 6-8 slots. YOur 220 will take up two slots then the 120 will take up another. That leaves you with only 3 left if there are 6 spaces for the future. Never say never:rolleyes:

It probably ends up being closer to 24 feet now that I've measured everything.

Something like this?

https://www.menards.com/main/electrical/circuit-protection-distribution/main-lugs/square-d-trade-homeline-trade-100-amp-6-space-12-circuit-indoor-main-lug-load-center/hom612l100s/p-1444444042902-c-6438.htm

I can use a 50 amp breaker and 6 gauge wire to supply it?

I like that, but that puppy is 100 amp sub panel. You have a 200 amp main panel? If so, you must up your wire size going to the sub panel. #3 is required for 100 A

Yes. 100 amp is max for panel. the 50 amp breaker goes in the main panel to feed it.

With a sub panel, you are supposed to run 4 conductors. 2 hot, a neutral, and a ground. The ground bar and neutral bar should be separate in the subpanel, with the ground bar connected to the ground wire from the main panel, and the chassis of the subpanel.

https://static.onecms.io/wp-content/...SCW_280_08.jpg

Edit: you need to buy the ground bar for that panel, description said it isn't included.

I don't know if CA has other requirements, but you can put a smaller breaker in the main panel as long as the wire and panel are at least rated for that current.

I have done it and have never had issues with inspection. But then again, some of those guys are sleeping on the job.

Would this be the correct wire to run? (I know I don't need this much.)

https://www.menards.com/main/electrical/electrical-cords-cord-management/extension-cords/cerrowire-reg-soow-portable-power-cable/283-4204c/p-1444439076381-c-6410.htm

Is it all interior run between the two panels? Even if it is, run it through conduit. Use flex if inside to inside, use rigid if it goes through the exterior. Don't use the ext. cord because it wouldn't past code out here.

Run wires (not Romex or extension cord) in the conduit for much needed or better protection. Like Dad911 said, make sure there is no bond or connection between the grounding and the neutral buzz bar in the sub panel.

I was going to run conduit from the main panel to the sub panel. The wall the main panel is on is the same wall inside the garage that the sub panel will be on.

Make sure you don't run NM cables (Romex) inside the conduit. Not legal here and most states (maybe all?) that I know of. This should include that extension cord from that link. I am not sure if it is code to have Romex inside the garage, exposed? That means, it has to be covered behind drywall. If code allows, you may be in luck to save yourself a bit of work. Still, I like conduit for better protection.

Chris, that cable is for portable power cables - like for an RV or generator hookup - not for power runs between panels.

That's why I asked. It was the only 6/4 cable I could find at Menard's.

I couldn't deal with the Menards sight - so I used HomeDepot. Is there a reason you want to use conduit? It's much easier to just use romex. This is 6 awg 3 conductor and ground - to use between the panels. It's not cheap - as copper is not cheap. Seems 50' will be plenty for your to use between the panels.

https://www.homedepot.com/p/Southwire-50-ft-6-3-Stranded-Romex-SIMpull-CU-NM-B-W-G-Wire-63950032/204765156

Not sure if anyone gave a suggestion about the 240 V outlet/plug. This is the standard most used:

https://www.homedepot.com/p/Leviton-20-Amp-Industrial-Grade-Heavy-Duty-Self-Grounding-Single-Outlet-White-5461-W/301207446?MERCH=REC-_-rv_search_plp_rr-_-309534130;309522474;309534540;312906038;311166334; 312562587;312562585;312562576;312303422;311709813; 311709809;-_-301207446-_-N

http://forums.pelicanparts.com/uploa...1586133238.jpg

Of course - you'll need a mating plug.

https://www.homedepot.com/p/Legrand-Pass-and-Seymour-20-Amp-250-Volt-Plug-PS5466XCCV4/202664478

http://forums.pelicanparts.com/uploa...1586133365.jpg

So don't buy the Romex and buy 25 feet each of red, black, white, and uninsulated 6 gauge?

Legion - A couple of things about 240. The gauge size for for the hots (Red & Black), 6 gauge. The Neutral is 2 gauges higher, so the white wire is 8 gauge. The ground wire is 4 gauges higher which is green or uninsulated, 10 gauge.

A "Romex" is a self contained insulated cable with the proper mix sizes and colors.

Most of the time, the wires are all black, but colored tape is added at each end to identify the different wires. If you have access to colored wires, it is better!!!

I definitely would use a conduit of some type. the plastic "sealtite" is fine, I use it all the time indoor or outdoor. For a garage, I usually set it up like it was outdoor since there is a much higher chance of water/liquids.

I've done standard 15 amp electrical sockets, so I am familiar with running Romex for that. look 171's post said not to run Romex in conduit. I assume it is a code issue? If it is okay to run Romex in conduit, I'd much prefer to do that.

And yes, I had the same thoughts about liquids in the garage and decided to run it that way for exactly that reason. That, and I have small children.

Yes, you can run a combined "cable" in conduit. It is not as easy to find the combined cables.

That said, the cheapest way to go for 25 feet of #6 is to buy about 120-130 feet of #6 black and, color code with tape (green, red and white, no color for the black). And run it through 1" Sealtite.

You can strip the jacket from the romex. I've done it for short lengths.

Do you really need a subpanel? You can run multiple circuits through an oversized conduit if you have enough room for the breakers in the main panel. Then you can do all this with a roll of black thhn#12 and some white and green tape (as R-B pointed out)

I'd like a subpanel in the garage to make reconfiguring for future large tools easier.

If you have the Romex already, then strip off the Jacket like Dad911 suggested instead of spending more money on wires.

Yep, no Romex in conduit out here. I have done it with short length of 2-3' from the attic to a HVAC disconnect or isolator on the roof. Any longer then that, it wouldn't pass inspection due to heat issue associated with Romex inside conduits.

How much more room do you have in that main panel? Like Dad911 say, run circuits off there. Are they all full size breakers? Is there enough room for tandem or "slim" breakers.

I have no room in the main panel. I just had my electric hot water heater replaced with a natural gas unit, so that freed up two slots taken by the old 30 amp breaker for the hot water heater.

Got it.

Normally, stranded wire is used in conduit pulls since the solid wire used in romex doesn't turn/bend in conduit L's (or other bends) easily.

It should be a straight 20' run from the panel to the wall, and then up 90º for a 3' run to the subpanel. So I'll have two 90º turns, one from the main panel to the main run, and one from main run to the subpanel. I was going to use an elbow like this below the subpanel to make the run easier to manage:

https://www.google.com/imgres?imgurl...MygGegUIARCnBA

Does anyone know how high off the garage floor is code for a subpanel?

240.24 Location in or on Premises.
(A) Accessibility. Overcurrent devices shall be readily accessible and shall be installed so that the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than 2.0 m (6 ft 7 in.) above the floor or working platform, unless one of the following applies:

Installed the subpanel and ran the conduit today:

http://forums.pelicanparts.com/uploa...1587169131.jpg

Not sure how to complete the run to the main panel:

http://forums.pelicanparts.com/uploa...1587169225.jpg

Run conduit right into the main panel. Use clamps https://www.orbitelectric.com/flex-connectors-screw-in-type.htmlto make sure conduit is connect to the panel tightly. Fish wires through. I normally try to run wires first so I don't have to pull the wig wad of wired through but not always possible. I suggest flex instead of rigid conduit to eliminate having to purchase a conduit bender.