ELECTRICAL HELP

Moving into a new construction house. Part of the garage will be a small workshop-table saw/drill press/air compressor/a few lights/ and outlets. I need to run wire from the panel in the basement to the far side of the garage where my workbench/shop will be. It's about 60 feet of wire from the panel to the first set of outlets. I'm thinking of using two 12/2 wires-2 20 amp CBs and dividing the shop area in half with each having it's own branch and CB. Would running 10/2 and powering the whole thing be from that be any better? My old garage workshop would blow the CB If I ran my table saw while I had some of the lights on-it had some serious wiring issues. This is my last go around at building a workshop, so I want it to be right.

Mount a 60 amp sub panel in the garage. Supply 20 amp T-slot receptacles, a welder and air compressor from it.

10gauge used in the first description instead of 12 would provide less voltage drop, and support the heavy loads you might encounter. It might be overkill, but power is important, and using an extension cord to get out of the shop needs to have all the source voltage it can get. Jim

60 feet I would run 3-6 and add a sub breaker panel but I like to do things over kill so that in the future if you want more power you can have it

That's too much for 2 20 amp circuits. It might work, but you'll be having the same tripping, dimming problems as before. Always plan for expansion, better to have too much than not enough.

I would go with 3 #6 THHN copper (2 lines and a neutral) and a #10 ground inside PVC conduit, underground. Feed off a 60a breaker from the house. Set a subpanel in the shop, drive a ground rod.

I put in a 125 amp subpanel about a year ago and was told by electrial contractor and electrical supplier to run 4 #6 copper wires ( 2 lines and a neutral) and a # 6 for ground.I am feeding off a 100 amp breaker in a 200 amp service panel.

I would put a sub panel in the garage and be done with it.

You are way undersized, should be at least #2 copper on the 3 conductors.

I re-figured it, could get by with #3 good for 100 amp, #2 for 125 amp.

I went and checked wiring and it is #2 not #6. But all 4 wires are # 2 even the ground.

First, you want to split your lighting from the outlets. As you've no doubt already experienced, it's no fun sawing a big board on your table saw and having the lights and saw quit at the same time. You need at least one 15 amp lighting circuit. Also, by eliminating the lighting load from your outlet circuit, you'll be able to draw current from the outlets before you trip a breaker.

Now you need some 20 amp convenience outlets around the garage. You can run a lot of stuff off a single 20 amp circuit, as long as you don't try to run it all at the same time. Since it's in the garage, this circuit should be GFCI protected. Sixty feet of wire isn't going to have much voltage drop at 20 amps if you use 12 gauge wire; about four volts. If you make the long run with 10 gauge, you'll shave a couple of volts from that, which probably won't make the difference between tripping the breaker with your saw or not. But two volts is two volts.

It's obvious you have only 120 volt equipment. But you're limiting yourself if you don't have a 240 volt circuit. Sooner or later you'll want to ditch your small air compressor, and you'll need a 240 volt circuit to power a decent-sized compressor. And you might want a welder some day, or maybe a bigger table saw. If you have a subpanel in your garage, it will be simple to add more circuits. Otherwise, you're going to be running another heavy romex cable from your panel in the house. If if has any circuits, left, that is. Putting in a subpanel now is more work and expense, but it can save you a lot of aggravation down the road.

Skybow, As usual, anytime an Electrical or Legal question is asked, you get more responses then any other subject.

You state ".... This is my last go around at building a workshop, so I want it to be right. ..."

It sounds like you don't have any high amperage loads planned (maybe 15 to 20 amps MAX), its NOT like you're powering a Machine Shop with welders and huge air compressors etc. HOWEVER if you're going to power a garage its not all that much harder or expensive to install say at least a 60 amp service with BOTH 120 and 240 volts so you have two separate 120 volt leg/branches (say 1 or 2 for receptacles and another for lights) PLUS 240 available for a small air compressor etc. or future expansion. I say that even though your post talks like maybe 15 to 20 amps is all you need ITS NOT ALL THAT EXPENSIVE OR DIFFICULT TO RUN a 60 AMP 120/240 service which allows for expansion versus ONLY 20 or 30 amps to the garage.

That being said plus your comment "This is my last go around at building a workshop, so I want it to be right" here is what I recommend:


Install a 60 amp two pole branch circuit breaker in your homes panel.........

Run Four No 6 THHN Copper Conductors in PVC type conduit to the Garage (2 UnGrounDED Hots L1 & L2, One Grounded Conductor
Neutral, One Equipment GroundING Conductor. NOTE you could use No 4 to reduce voltage drop if that was an issue.

In the Garage install a 120/240 volt 60 Amp SUB Panel which has the Ground Buss separate and insulated from Neutral Buss.
The panels metallic tub case/frame bonds to the Equipment Ground Buss but NOT the Neutral Buss

Out of the garage SUB Panel you could run one or two 20 amp 120 volt 3 #12 wire branch circuits to 20 amp 120 volt
NEMA 5-20R convenience receptacles.

I would power a lighting branch circuit by itself and NOT mix it with a receptacle branch circuit.

In a concrete floor garage, I would use GFCI receptacles.

NOTE if you wanted to power say a freezer out there, it can be NON GFCI provided its a single (NOT duplex) receptacle in a
non readily accessible location (say hidden down behind the freezer) as best I recall but no warranty as codes may have
changed

NOTE IF YOU WANT TO RUN ONLY A 30 AMP CIRCUIT out there, Id still run BOTH legs so you have 120 and 240. Still it would
require you to run FOUR wires (2 Hots, Neutral, Ground) and still, yes, you can have two legs of 120, L1 & L2. You're
talking No 10 or No 8 wire in this case (to allow for voltage drop which depends on amps and distance and wire size) and a
30 amp 2 Pole Branch Circuit Breaker in the homes main panel. YES A BIT CHEAPER THEN THE 60 AMP SERVICE I SUGGESTED. If you
want to run a 100 amp service out, the its bigger wire and bigger breaker etc. etc.

Its your money and your choice. If in doubt I advise you to check with your utility provider and local authority and the NEC if applicable and if adopted (and if so what version) in your jurisdiction and do as they say NOT any of us here!!!!!!!!!!!!!

John T Longgggggg retired AC Power Distribution EE so no warranty, check with local utility and authority

PS NOTE you asked if running 10/2 would be better ??? YES its better then 12 to reduce voltage drop BUTTTTTTTTTT to "split" and have TWO 120 volt branch circuits in the Garage, YOU STILL NEED FOUR WIRES NOT JUST THREE That would be 10/3 plus Ground. And in the Garage you still want the Neutral and Ground Busses separate and isolated.

GOOD JOB, The NEC has certain "Minumum" requirements but that doesn't mean you can use BETTER then minimum and where life safety is concerned when I was a design engineer I preferred to err on the side of safety myself.

John T

OOPS MY bad, I was still thinking 60 amps as the original post NOT 100 grrrrrrrrrrrr. I was talking more about de rating of the Equipment Ground which I didn't practice usually.......

Sorry for my confusion, gettin old lol

John T

sure never heard of a citizen band radio pulling 20 amps

I'd do what John T and others suggest, and not try to run 2 individual 20 amp 120 runs....

Cost will be pretty close either way really, and you will have many many more options don the road.

A 60 amp 220 sub panel gives you so much more flexibility.

Paul

Way to scientific for me. I'll stick with my 1930ish Delco generator.

I don't blame you, those were neat old gensets

John T

Calculate lighting load.If using 15 amp lighting circuit figure 12 amps load per circuit. Recepatcles as needed after calculating machinery loads. { no continous loads unless running 3 hours or longer.] A few machinery circuits. 20 amp loaded up to 16 amps eaCH MAX only.