Wiring-what do I need?

[Dragster Racer]

I do my own electrical, but only know enough to be dangerous.:thumbup:
I am wiring my 40X40. Here is what I figured I would run before putting up OSB:
-#12 wire 20A circuit for each of the three walls with no doors, 3-4 outlets each wall
-20A #12 to light swtches next to panel. 2 or 3 switches to conrol lights with #12 running to light outlets (do I need to go bigger on wire to switches? 30 4' fixtures or so)
-15A, #12 circuit to ceiling fans, 2. May run lp furnace on this circuit too
-Wondering what to run for compressor, will get 60 gallon medium duty unit
-Need to have a couple 220V outlets for welders, need advice on this one, wire size
-Considering 1 or two electric Dayton hanging heaters.
Help a hack keep from burning the place down will ya!

[pattenp]

Most of what you're saying looks ok. The 15A circuit only needs #14 and you need to know what the amp load is on the welders you have to determine the circuit size. There is a section in the NEC that cover sizing circuits for welders.

Your local inspector will let you know what's right or wrong. Take your wiring plans to them to look over.

[Charles (in GA)]

I seem to "love" answering electrical questions, which is not good for an amateur like me. Anyhow, keep in mind, that lighting is considered by code to be continuous use, and as such, you cannot load the breaker (or any other part of the circuit) over 80% of its rated capacity, thus a 20 amp/12 gauge circuit is limited to 16 amps. You will need to total the amp rating on the placards of your light fixtures to calculate the max number of fixtures you can put on one circuit. Plan your circuits so you can only light one portion of the building to save power.

You are in a workshop where loads tend to be higher and more varied than a residence, stick with #12 wire or better for all circuits. See my post #9 in the "going goofy" thread in electrical/lighting for my de-rating discussion. This is good reason to use #12 wire for all circuits, and not #14.

Heaters, you will need to know the amp loads before you attempt to run any wires.

Air compressor, you could anticipate the worst case scenario and run #6 to a tiny subpanel where the compressor will be located, and then you will be covered for virtually all possibilities.

Do yourself a favor, and SCREW on the OSB on the wall where the panelboard is located. This way, in the future if you need to run additional wires in the panel, you just take down the OSB and do the job and put the OSB back up again.

Consider buying a panel of the same brand that uses the same breakers as your house (unless your house is old, decrepit, or has a Federal Pacific panel) as this will make the spare breaker issue much easier in the future. My house has a Square D board, and I don't like Square D, so I put a Siemens panel in the shop, but now I have two batches of mixed, odd, spare breakers, that don't interchange.

Charles

[brad d]

I went with #12 20amp's for my wall plugs, and #14 15amp for my two fans and T8 lights

[Aceman]

#12 wire 20A circuit for each of the three walls with no doors, 3-4 outlets each wall

OK.


-20A #12 to light swtches next to panel. 2 or 3 switches to conrol lights with #12 running to light outlets (do I need to go bigger on wire to switches? 30 4' fixtures or so)

I'd break it to more than one circuit. 4 bulb T8 fixtures pull a little less than an amp a piece. You want to shoot for a maximum of 16 amps on a 20 amp breaker or 12 amps on a 15 amp breaker. Always good practice to leave a little wiggle room on a circuit in case you add more fixtures. I like #14 for lights usually, a little easier to work with and it helps break up the circuits a little more since it has a less ampacity. Also, if one light dead shorts you're not taking apart 20 of them to find the one bad light that took out the whole circuit.


-15A, #12 circuit to ceiling fans, 2. May run lp furnace on this circuit too

I'd run #14 unless you only want to buy one type of wire(#12).


-Wondering what to run for compressor, will get 60 gallon medium duty unit


Almost all home garage compressors will run on a 30 amp #10 circuit. I would think #8 would cover it, but it's best to find a compressor you like first so you get it right the first time. It's not fun spending money to over do it or worse yet, accidentally undersize it.


-Need to have a couple 220V outlets for welders, need advice on this one, wire size


Welders have their own requirements that allow you to use smaller wire than is typically allowed due to their duty cycle. I'm not going to recommend that method however since anything can happen. The first time somebody plugs something into that receptacle other than a welder that pulls a serious load you've got problems. With that said, #6 Romex combined with a 50 amp recep should cover most welders. Even the smaller welders usually come with a 50 amp cord end to match.


-Considering 1 or two electric Dayton hanging heaters.

Get the specs and follow their requirements for wire size. I would not try and guess on wire size, same advice as the compressor above.

[tdkkart]

I do my own electrical, but only know enough to be dangerous.:thumbup:
I am wiring my 40X40. Here is what I figured I would run before putting up OSB:
-#12 wire 20A circuit for each of the three walls with no doors, 3-4 outlets each wall


I'd consider more outlets, at least one every 6 ft, and preferably 1 4 outlet box every 6ft if it was mine. Do some planning about where your equipment is gonna be and remember that most everything comes with 6ft cords.
A bench grinder on a pedestal, beltsander, drill press, parts washer etc will all likely land in the same area.
You can do one 20A circuit for each wall. At 6ft spacing you'll have 6-8 outlets/wall but you'll likely ever use more than 1 or 2 at a time so overloads shouldn't be a problem.
Outlets are cheap and easy to install now, PIA to do later when you realize you need more.

All but the most obscene:thumbup: compressors will run on a #10 30A circuit.
If you tend towards the obscene, go with #8 wire just in case.

Unless you're thinking about a big TIG welder, a 50A circuit will handle anything else. Keep at least one welder outlet as close to the main panel as possible.

[tfi racing]

All good advice here,here's a couple more things to add:
Separate switch for the door openers,so you can disable them when you are away,sometimes they can pick up a stray signal and open!
A couple of ceiling outlets for light cord reels
Double receptacles where you want to put your bench
A few outdoor receptacles,at least one by the big door and a welder outlet close to that door(inside,of course) in case you need to weld something that won't fit inside
Separate switches/ckts for sections of lights,so you don't have to turn all of them on at the same time
Depending on your location,some additional lighting outside is never a bad idea.
Now is the time to add a few items,it is a lot cheaper and easier to do it now than when all is finished.

[Dragster Racer]

This ended up being one of those threads with enough great info that it is worth printing it out! Thanks guys. Outside lighting is done. Two metal halides and two cf's. I have outside outlets on one side, but need to put two or three more. I'm ready now to roll up my sleeves and get to work. I figured I had better rough this in before doing the insulation. It's getting cold now!

[trainer]

Don't skip the permits and inspection! Doing things right isnt any harder or more expensive than doing it wrong.
If something goes wrong and you do burn it down, it's alot easier to get your insurance to pay up if you've jumped through the right hoops.

[Dragster Racer]

No hoops availible. Waaay out in the country, and the county doesn't do that sort of thing. I have a permit for garage build, but that is all that is required.

[pattenp]

No hoops availible. Waaay out in the country, and the county doesn't do that sort of thing. I have a permit for garage build, but that is all that is required.

So what part of the country does't require an electrical permit. Maybe I should ask first what country you're in.

[carguykeith]

I didn't see mention of a 220 circuit for a lift, if you ever think you will ever install one, it's better to pre wire it. Also while your wiring, don't forget your t-stat wire, garage door opener wire, and speaker wires, no need to have that crap outside of the walls if you don't have to.

Oh and buy the drill bit that can hit metal because you WILL hit a nail! I ended up buying and destroying (3) of the standard spade bits, but could have just gotten one of the better ones and kept it for the next project...

I had never done a panel before so I pulled the cover off of my main panel of the house and used it as a reference when I wired up my sub-panel for the shop. Seamed to help me at least...

[sberry]

I am with ACE on this one too, I like to split things up a bit and use 14 for lighting circuits and to some dedicated appliances, maybe the furnace, etc. I prefer to keep lights and general use circuits separate and use 12 on anything with an outlet. I also agree that the majority of comps, any of the 5 hp rated units these days use a 10/30 and any welder found in home shops are fine on an 8 wire @ 50A, 200A migs and under a 10/30 makes a tailor made circuit.

[boiler7904]

Only thing that I would add is run an empty 1 1/2" or 2" conduit to the attic for future use.

If the building has an attic, run a lighting circuit up there and at least a couple of 20 amp receptacles in case you need to work in the attic - adding more wiring down the road comes to mind.

Install a 20 amp 120v receptacle next to each welding receptacle. Where you're welding, you're also grinding.

Double the number of receptacles you think you need at your workbench(es).

Install wall receptacles at least 48" above the ground. If you have a sheet of plywood leaning against the wall, the receptacles are still accessible. You can also access them over items like the welder, pressure washer, tool carts, etc.

Plan for low voltage items like phone, speakers, intercom to house, etc. now and rough it in as you do the electrical. Install receptacles near low voltage points for things like stereo receivers, tvs, cordless phones, etc.

And last but not least, a dedicated receptacle for a beer fridge. I can't stress this one enough!

[JohnK007]

And last but not least, a dedicated receptacle for a beer fridge. I can't stress this one enough!

This is most important. I would seriously consider tying that circuit in to a stand-by generator just to be safe!

[Dragster Racer]

LOL! Not a bad idea.
I finished up all the outside outlets today. Did 5 with covers, all tied to a GFCI breaker. These always take longer than I anticipate since I have to cut a hole in the metal, mount a box, and on these, I had to run a pretty long line from the breaker box, over the garage doors. I actually put one between the doors, for a handy one in the drive. I can cross that one off my list now.

[Dragster Racer]

Had a few minutes today, so I wired the 20A 220V circuit for the hanging electric heater. I think that thing will do OK when I have the entire shop insulated. I will probably let the electric try to keep the temp maintained, and use the bigger propane when it needs help or for recovery. Helped a friend wire his entertainment room in his house this afternoon. I don't like working with boxes that are basically full. Makes everything tougher.