Discussion in 'Electrical and Wiring' started by victorstaggers, Dec 1, 2012.
I am trying to connect power to my detached garage, from my in house breaker box. Any suggestions?
Decide whether you want a subpanel in the garage, which depends on the distance to the garage.
For working on your load center, level 2 arc flash gear is recommended.
Figure out how much power you need. Then you will know if you need a sub panel or single circuit. Dig a trench 2 feet deep and bury the proper cable or conduit and wire it.
Plan ahead, and try to think of any/all possible future uses in the garage. Such things as--will you ever want to hook up an arc welder, or possibly fire up a kiln for fusing glass or pottery? If you only run a single line of 110 v., and later decide you really need 220 v., you will kick yourself for not putting in the heavier line wire the first time around.
I think a separate sub-panel in the garage is a must. Even if you never have the need for future, larger draw circuits, as it will save a trip back into the house to reset any breakers that trip. If it were me, I'd definitely want a dedicated appliance circuit (20-amp, 12-gauge wire) or two, and then at least one lighting and future electric garage door opener circuit (15-amp, 14-gauge wire), in addition to a 50-amp welding circuit. Pulling them all from the new sub-panel, leaving some room to spare for future circuits. And don't forget to apply for a permit, if required by the AHJ in your area.
The choice seems to be wiring your garage in increments
going for the full monty:
a lump sum paid now
small lumps paid over years, as you need them.
Note that half the people move in 7 years and almost all move within 14 years so you should judge the likelihood that you'll need the full monty within X years.
Costs & likelihoods will give you a mathematical way to make this decision. It's like another opinion but it's based on science so I guess that makes it a matter of fact.
A wise person once said a man can never have too many outlets in a shop/garage.
But not all outlets will be used at the same time. The NEC term for this is demand factor or diversity factor.
If you dig the ditch for underground just put in a bigger conduit so if you or someone else want to up grade, it will be no big deal.
Far easier to make all wiring runs when the conduit is placed, especially if it's a long run with some dips and doodles in it. If you choose not to do that, then at least include a pull-wire in the conduit. And use much larger conduit than actually required, so you're not talking to yourself for a whole weekend, trying to jam more wires into/through a tube that's too tiny.
I would run 10-3+ground to the garage. Cheapest is underground cable. You can put a small sub panel in the garage.
This assumes you will not be doing electric welding in the garage. If you plan on doing welding, then 6-3+ground. Or better yet 100 amp service.
Conduit is always a good thing.
I need to rewire mine, it has ancient wires just buried 6" under the ground - no conduit.
I still haven't decided exactly how I'll do mine, but I had everything dug up for other reasons so I buried the conduit so that I'll have flexibility later. It might be a good place to start.
Even if you're not doing the sub panel now just spring for the 3-wire cable and cap off the third wire on each end. Then it's there for the future.
Code here called for 2 grounding rods for the sub panel when I wired my garage. At least that's what my electrician told me to do, I'm not actually sure what the code is. I did all the work and then just had him check it out.
And yes, flipping a thrown breaker in the garage sure beats running in the house and down the basement.
Also, if the first outlet in your line is a GFCI then the subsequent outlets, run off the load terminals, don't have to be.
I've never thought of this, probably since I don't have a garage. And in a workshop it is likely that lines will be overloaded.
I buried 4" PVC from my meter to my barn and pulled 3 single-0 gauge wires thru to a sub panel. My wife never knows when I am using too much power. It cost more to rent a Kubota than the other stuff and it was fun digging also.
As long as you are digging a trench and burying a conduit, throw a second conduit in the ground for low voltage (coaxial cable, data/phone lines, whatever). You may not need them right away, but if you someday decide you would like them, then the pipe is aleady buried and you won't have to dig another trench.
I see Victor hasn't come back he problably thinks we're all crazy.
Victor, Hey Victor, everything OK out there?
Have you done any work on that garage electrical, we are concerned here.
Another thing to consider when sizing your conductors is the length of your run. For every 100' of wire length you should upgrade to the next wire size. If you have questions look up voltage drop tables to determine what the wire size should be for load and length of run.
I've heard 5% max volt drop from main load center to farthest outlet.
Wondering about your 100' rule, as I have been, I did a spreadsheet to test it.
Below, for 11.8A, for copper at 20C, for 200', 400' etc., loop distance (100', 200', etc., one way) for
100' one way, #14 the drop is 6v
200', #12, 7.5v
300', #10, 7.1v
400', #8, 6.0v
so it sort of works. Thanks.
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