Hello,

My home is being rewired (to 100 amp) to eliminate all of the knob and tube wiring. I also need to have my 2 car detached garage rewired. It is approx. 50 ft. from the house. I need lighting and some outlets. It will be used for recharging the mower, a soldering iron, a few power tools, etc. I would like to add a door opener in the future.

I was first told the wire would have to be 2 ft. deep, then later was told 3 ft. deep. 50 amp service has been suggested w/a breaker box wire running overhead to the garage. I am worried that the children may knock the wire down when playing ball in the yard. I have been reading through your responses and realized there is a lot to all of this, much more than I thought or know anything about: different conduits, wires, sun resistant wires, and so on.

Questions:
Is one method better than another?
Is one more cost effective?
What materials should be used?
Is 50 amp sufficient?
How much should a job like this cost? (I am willing to dig the trench if underground is recommended)

Thank you for all of your help.

educateme

Hello,

My home is being rewired (to 100 amp) to eliminate all of the knob and tube wiring. I also need to have my 2 car detached garage rewired. It is approx. 50 ft. from the house. I need lighting and some outlets. It will be used for recharging the mower, a soldering iron, a few power tools, etc. I would like to add a door opener in the future.

I was first told the wire would have to be 2 ft. deep, then later was told 3 ft. deep. 50 amp service has been suggested w/a breaker box wire running overhead to the garage. I am worried that the children may knock the wire down when playing ball in the yard. I have been reading through your responses and realized there is a lot to all of this, much more than I thought or know anything about: different conduits, wires, sun resistant wires, and so on.

Questions:
Is one method better than another?
Is one more cost effective?
What materials should be used?
Is 50 amp sufficient?
How much should a job like this cost? (I am willing to dig the trench if underground is recommended)

Thank you for all of your help.

educateme
Underground would be better and safer. The codes are different in different areas of the country. I know in Albany NY the depth is 4'. Here in Modesto,CA, it's only about 1'. It all depends on the frost line. Make sure you use exterior wire, and conduit. I'm not sure of the codes here but you can get the book from the local power company. Most will even have diagrams. Hope this helps a little.
Matt

Also,you can rent a trenching machine to do the digging ,its like a oversized chainsaw and will do the work in no time(electricians and plumbers also have these and would do the job for X $ per foot)

If you got an electrician to do the work(trenching) you could ask him directly what wire and conduit to use.

And remember,Always call JULIE before you dig(local utilities company will have their #)

Questions:
Is one method better than another?
Is one more cost effective?
What materials should be used?
Is 50 amp sufficient?
How much should a job like this cost? (I am willing to dig the trench if underground is recommended)

educateme

Each method has it's pros and cons. Underground for a 50 foot run is better for a few reasons, safety and appearance for example. Overhead would be subject to damage, etc for obvious reasons. Ned to keep it at a height that it would not be hit. Exterior conduits would need to be surface mounted on each building up to the height the cable is needed, a min of 10 feet with no vehicle traffic.

The con to underground is the trench, not impossible, but back breaking unless you rent a trencher. Once the trench is done, then the rest is fairly easy.

I would use PVC conduit Schedule 40, and associated fittings, which is all typical and very accessible at home remodel stores.

50 amp seems to be more than sufficient for the loads you mention, with a decent cushion for added load. This would require a 1 " PVC conduit, 3- #6 copper wire with either THHN/THWN or XHHW insulation, and 1- #10 copper green as the equipment ground.

At each building you would need a elbow to rise up out of the trench and an LB fitting for a hard 90 deg turn into the building. Inside you can change over to cable, using a 4-11/16 in square junction box and cover. At the garage you can continue the conduit directly to the subpanel.

The minimum depth of conduits is listed in Table 300.5 of the National Electric Code (http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70&cookie%5Ftest=1). In your situation the min depth will be 18 inches.

Any info provided by a utility company may or may not follow code, as they are exempt from building and electric codes. Always consult with local and state codes for any work done, as each city and state, while they all adopt the NEC, do have minor changes and waivers. Some areas, due to soil conditions require a bed of sand above and below buried conduits.

At the subpanel, be sure to have a separate equipment ground bar for the green wire, and connect only bare and green wires to it. Keep the neutral insulated and isolated by using the neutral bar in the panel and do not use and screw or jumper to bond the neutral bar to the metal can of the panel.

Thank you for the info. I thought that underground would be better also. Do you have an idea of how much this job should cost for an electrician to do?
I really appreciate all of you and your assistance.

educateme

If you do it yourself probably around $150-200.00, that's materials and sweat equity. If you Hire a electrician multiply that by maybe 15x's. They don't come cheap. You can probably find a good handyman that would help you for about 10.00 an hour (under the table of course). It really doesn't sound like a big job at all and shouldn't take long at all.
Good Luck with it. What part of the country are you located? I should have asked before committing to it not being hard.

If you hire a handyman, make it clear you are in charge, and follow tkrussell's instructions to a T