Hi all - my first post, but I've been lurking for a while. What a great web sight and a wealth of information!


I am building a garage/workshop. It will be detached from the house (about 120' away), 40' x 50', and conventional construction (stick built - not a pole barn or metal building). I have a couple questions on getting utilities to the building.

What do you recommend for water supply? I see the lumber yards have a flexible black plastic pipe in a 1" by 300 ft roll and I believe it is good for potable water.

How about electricity? I have a 200 amp panel in the house and would probably use a 100 amp panel in the garage. What type and gauge wire/cable should I run from the house to the sub panel? Would this be something I can bury or do I need to run it in conduit or pipe?

How about natural gas? I believe the supply line to my house is some sort of flexible pipe. Don't recall seeing that at the lumber yard - where would I pick up any supplies?

Lastly, can I bury all of these utilities in one trench? I would guess that water would go down first (deepest), add a few inches of fill, then electricty or gas, etc.

I'm pretty mechanically/electrically inclined, so I plan to do most of the work myself. I have contracted out the concrete and brick work and would not hesitate to contract out any of the above if it looks like more than I can handle.

Thanks so much for your help,

Skyking1992

 

If installation is to be permitted and inspected check with local building codes division inspection and permits for requirements on depth of trench and combining utilities in trench. Local utilities office can give you installation requirements info as well.
Keep in mind non inspected installs can be homeowners insurance problems (electrical fires )as well as if you sell or refinance property.
good luck with your shop.

 

Most locals will permit the owner to rough in the electric lines, but require that the final hookup be done by a liscensed electrician. You can buy cable that can be buried, check with your local building supply store.
I would probably not even try to do the gas piping on my own. You make a mistake and the results can be "spectacular"!

 

also, when running power lines underground, check with your code for burial depths. i think its like 12" for steel conduit, and 18" for plastic here, or like flyboy said, get the outdoor cable, (grey coating). gas u can run with copper tube, comes ina roll at your hardware store. and i dont beleive water needs to be as deep as electric, and i have no idea on gas depth. if ya still have any questions, my dad's an architect so ask away and ill getya informtaion if ya need it.

 

If you do use copper for your gas lines, make SURE you get the correct type. There are 2 grades, I THINK they are M and K. You want the thicker stuff.
The chemical they put in natural gas to give it it's distinctive odor has a nasty habit of causing copper tubing to flake off inside, which could damage your heating equipment, and over time it will weaken the tubing.

 

Thanks for all your help. I will check with the county zoning office for any info. I live in an unincorporated area of the county, so zoning regulations don't seem too strict. I have a permit - two inspections are required, one before the dig (allready done) and one after final completion. Having said that, I still want to do things right.

Skyking1992

 

When I built my garage in TN I went to the electric membership to get a service on the building with its own meter but the engineer at the office told me to run the electric out of my breaker box in my house which is a 200 amp service. He said it would be alright to run 90 amps to my building. I ran 3 number 4 THNN standed wires with a number 6 stranded THNN for an extra ground in the grey conduit plastic. This is what an electrician who is a friend and also helped said to do. I also put an 8' ground rod in at the building and grounded there too,this is for the possiblity of lightning striking the building. I have never had the need for more than a 60 amp breaker and I do use a welder sometimes. I would check local codes to see if you could do something like this it was really simple did it in a day about the same distance as you are going. Hope this helps you.

 

DO NOT USE THE BLACK FLEX PIPE FOR WATER!!!!!!!!!!!!!!!!!!!!!! This is more than likely for irrigation use and is not intended for constant pressure use.Use schedule 40 pvc and you wont have any problems

 

Most states have laws that states that the homeowner can do any type of work they want to do on thier own house I know for a fact thatall new england states have the same laws which states that the only people that can do work on a house is the homeowner or a lisenced professinal so he could do all the wiring himself, also I know that atleast in rhode island you only need a construction permit if a contractor is doing the work or if your building a NEW structure of some type

 

Why not? What happens? We used it on our ranch for long runs in the water system. It's a lot cheaper than 10ft pvc sections.

 

Different types of plastic have different chemical compositions. I know in Lincoln that the white PVC and the gray stuff are the only plastics approved for supply lines.

 

There are many different plastic pipes available, one of the more common plastic flex pipes used for supply lines is Polyethylene plastic tubing. This is probably your least expensive way to go for your supply line, and it is it is flexible, tough and doesnt get brittle like PVC.

Water Pipe min 12" deep and 6" below frost line



Gas piping min 12", 18" deep for plastic, 18g copper tracer wire must be run with plastic Polybutelene pipe the entire length.

The gas line will need to have a 15 minute pressure test to assure there are no leaks. The pressuse will depend on the code your juristiction uses. (3psi IRC, or 10 PSI UPC).



For 100 amp electrical service 4 gauge copper or 2 gauge aluminum wire is the recommended size for carrying 100 amps.

You are required to have a seperate ground for your detached garage/shop.

The depth of the trench requirement for your electrical depends on if you use underground feeder cable or wire in conduit and the depth will change if it passes under a street or driveway.

Your county will supply you with the seperation requirements for the different utilities within the trenches.

 

Black water pipe...........yea, bad idea. Mine lasted 5 years I believe. Replaced it all with 1" PVC. Lots and lots of it. Three buildings and 3 freestanding outside faucets from a well. Would have been much easier to just use PVC from the start, just as easy, and sometimes easier to work with. Thats my story.

 

Polyethelene black f pipe will remain flexible and does not break down and get brittle like pvc pipe, what kind of black pipe did you use? What went wrong with it? I have some thats over 15 years old, sitting out in the sun and its just fine. On the other hand, I have some pvc that has been sitting out for 4 years and its shot, brittle and chalked up.

 

I have scanned the posts and they have much great info, and here are a couple more things to think about:

I would definitely use conduit over direct burial cable and don't be stingy on the size of the conduit. This way, if for some reason your power needs change down the line, you can upgrade easily. I'd use plastic conduit (it doesn't cost much more to dig a trench to 18" than less, and you may need to go at least that deep anyway, for frost heave) but use rigid (steel) conduit bends (wrapped in plastic tape) as the friction of pulling wires through plastic bends can melt and cut the plastic.

If you have a water softener in the house, you may want to run a separate line of softened water to the garage for washing cars, etc.

You may want to run a conduit or two for such things as TV cable, phone lines, burglar alarm, remote low voltage relays, switches, etc. Conduit is cheap and easy to throw in the trench at this point.

You cannot run anything other than the supply wires for the subpanel in that conduit, so if you plan on any kind of remote lighting (run, say, from a switch in the house), you will need yet another conduit.

Consider a conduit for extending the landscaping water supply if appropriate for your climate. (I'm in Phoenix, so if it ain't drip irrigated, it ain't gonna live!)

Finally, you will probably have a compressor in the garage and may want air in the front garage or wherever, so you could run an air line for compressed air from the garage. Use schedule 40 PVC ONLY where it is buried. Never use PVC for compressed air in any exposed location. Use copper from the bottom of the trench up.

Sorry this is so long and also if it duplicates anyone else's posting. Now's the time to think of these things, not after the concrete is poured! Been there; done that; never wear the tee shirt. Good luck with your project.

Jesse