dslreports logo
 
    All Forums Hot Topics Gallery
spc
uniqs
1064

whizkid3
MVM
join:2002-02-21
Queens, NY

2 edits

whizkid3 to jig

MVM

to jig

Re: get power to garage

said by jig:

Right now what someone has done is wire to what used to be an external light, looped through eye-hole screws for tension relief and then strung over a little walk way separating the garage from the house. no separate circuit breaker, no separate ground rod, and while i haven't looked, my guess is that the wire is probably bare at the eye-holes since it's been open to the sun for at least a decade.
Yeah - probably no good. Note, however, if you're only talking about a single or multi-wire branch circuit, then you don't need any special grounding like a ground rod, etc.
ideally, i'd like to run the power underground in a water proof conduit, and possibly run a separate ground rod and circuit breaker box so i can protect the garage door and a security system from whatever else is going on.
You will need a ground rod. However, it can not be separate, and must be tied to the grounding electrode system from the house. What you will need to do is have a properly sized ground wire from the main breaker box or disconnect, where the neutral is bonded to the grounding electrode system and the equipment grounding system. This is typically in the primary breaker panel of the house, but not always. If you have an external disconnect switch located outside the house by the meter, this is the point at which the house's neutral and ground are bonded together, and where your ground wire must run.
i think we have a 150A run to the house, and that entry is on the other side of the house from the garage. this probably means that we'd run something from the main house box under the house, through a crawlspace breathing hole, then to the underground conduit that would have to be only about 6" deep at most because it would cross (over) the new water main we put in.
Six inches is too shallow. With the exception of 120V, 20A, GFCI protected circuit which allows a burial depth of 12 inches; all underground one- and two-family dwelling buried circuits, must be a minimum of 18" deep, as per the 2005 NEC. Go underneath the water main.
i'd probably want the circuit breakers to be accessible from the inside of the garage (though maybe outside... probably doesn't matter a whole lot). the conduit would run about 14', then up the side of the garage and enter into the back of the new breaker box. whew.
That's fine. Its not as hard as you think. (Get kids to do the digging, or rent a Ditch-witch.)
OR, we could do the same thing except run the conduit overhead. i've wanted a trellis covering that walk way area for a while now, so we could run the conduit up hidden in the wooden support... though i guess if we try to get ivy or roses to populate the trellis i'd have to use weedwacker-proof conduit (never assume the gardener isn't an idiot, even if it's you).
You will need a carefully constructed support structure if you go this route, along with expansion joint(s) in the conduit; I suggest at each end. You will also need PVC conduit, rated for sunlight-exposure.
which option sounds good? should i run to a new breaker box? if i do have a new box, should i run a ground rod? what gage wire should i use if i plan on having something like a security system running 24/7 in there (total run from house circuit breaker would be something like 60-75')?
I suggest a small sub-panel in the garage. The size (ampacity) all depends on what you need in the garage; and what capacity you have left from your utility service. Without any other information, I would suggest a 240V, 60A panel, which will allow you to do welding, run compressors, table saws, etc. (30A may do it as well.) You will need space in your main disconnect panel for a two-pole, 60A breaker. You will need to run minimum # 6 gauge wet-rated wiring (THWN in conduit the entire length) or #4 gauge type UF (underground feeder) if you are planning to have it exposed in the crawl space. The ground wire must be a minimum of # 8 gauge. You will need to run four wires - two hots, a neutral, and a ground wire. Make sure your primary panel has available space in the neutral and ground buses for the #4 to #8 wires. If your main panel has its neutrals and grounds running to the same bus, then that is where you connect both your neutral and ground wires from the garage.

You can get a small breaker panel, rated for a minimum of 60 Amps. It should have its own main breaker (60A). I suggest getting a panel with 12 breaker positions, so you have plenty of room for two-pole 240 volt circuits, and others for lighting, receptacles, etc. Even run some outdoor outlets & lighting off of it. The breaker panel for the garage must have separate neutral and ground buses, with the neutral bus isolated (not connected) from the metal of the breaker panel.
we have some other electrical issues, so i could probably just have an electrician come and do it all, but i'd like to have a clear plan first. my guess is that any electrician will want to run overhead rather than underground.
I doubt it. Most would run it in PVC conduit from the breaker panel to the garage. That's how I would do it - and I'd make you dig the trench. I would use 1 1/4" schedule 40 PVC, and run all #6 wires (I like a good ground). I'd run a #6 solid bare copper ground wire from the ground bus in the garage sub-panel to a 3/4" 8 foot long copper-clad ground rod. I would have the ground wire run down inside the garage wall stud-cavities, and out beneath the surface of the ground to a completely buried ground rod. (This keeps the kid with the lawnmower from screwing it up.) I would also enter the garage underground with the PVC conduit if possible, directly below the breaker panel. If that is not possible; I would bury the conduit 24" as it approaches the garage, then transition with a PVC elbow; come up the side of the garage, and then enter the garage with an 'LB' type PVC fitting. I would seal both ends of the conduit with a sealing fitting at the point where the conduits enter the buildings, as well as where the conduit enters from the crawl space to the house, to avoid heat-loss and moisture ingress.

jig
join:2001-01-05
Hacienda Heights, CA

jig

Member

good suggestions, thanks!