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vinylman70 01-19-2010 12:23 AM

direct bury wire from house to garage??? help
 
i have a double wide and a 30x40 garage my electricity to my house is under ground. on my box i have room to tie in to it. i will have to run wire to the garage 160 feet i am going to use direct bury wire but what kind? where do i buy it? lowes? all the wiring in the garage is done all i need to do is get the wire in the ground and hooked up at the house and garage. i will be useing a welder that needs 240v the most i will use at 1 time will be welder,lights and radio i plan on doing this in the next week or 2 so all the help would be nice thanks.also i have never done this so before i go trying to hook it up at the house do i just turn the main braker off that is out side? also will there be enough power to run the house and garage all at the same time because right now i have extension cords run out there right now and when i use a grinder it dims the lights in the house i am assuming it is because of the extension cords. thanks for your time and help.

kbsparky 01-19-2010 03:45 AM

When I hear the term "double-wide" I think "mobile home".

If this is the case, then there should be an outside disconnect box with additional spaces for circuits to supply outbuildings, etc. This is where your feeder circuit for the garage should originate.

As for wire size, operating most welders would mean you need at least a 60 Amp feeder. I'd be willing to bet that many here would recommend a 100 Amp panel and feeder for the garage.

In any case, you can purchase a 4-wire underground feeder cable assembly called "URD" which would provide you with a 90 Amp capacity, if you bought the #2-2-4-6 Aluminum size. As for cost comparison, the #2 URD is probably less expensive than a #6/3-g type UF copper cable.

And, yes, it should be available at your local orange or blue home-horror store. :whistling2:

Scuba_Dave 01-19-2010 07:06 AM

What is the service feed to the house ? 100a ? 200a?
Min I would do is a 60a feed, 100a is a good idea if you have a 200a service

vinylman70 01-19-2010 02:58 PM

yes it is a mobile home and the box on the house where we would tie in to is 200a and the box in the garage is 200a i have been told we want at least 100a to go to the garage and been told to go buy 3 peices of number 1 wire???? that will be rated to at least 100a does this sound right?? also the welder i will be running is 185a 230v..also i cant remember if i was told if this wire was aluminum or just wire and is this stuff direct bury or would it have to be in conduit if you all would like i can take a picture of both the outside box at the house and one of the box in the garage if you all think that would help us out so we are not guessing. thanks for the help

Scuba_Dave 01-19-2010 03:21 PM

Detached garage you would need 4 wires:
2 hots, neutral & ground - ground wire can be smaller
Ground rods also required at the garage
#3 wire will give you 100a 7.6v drop over that distance (3.2%)
#2 wire will give you 100a 6v drop over that distance (2.5%)

So #2 copper would meet your needs
I'd use 2" PVC for ease of pulling, 1.5" would meet code

vinylman70 01-19-2010 04:02 PM

thanks scuba_dave so i need to buy 3 wires of number2 and 1 more wire for a ground what size would you recommend for the ground? and pvc pipe to put it all in. i should be able to do this all my self right without having to have the electric company connect it? reason i ask is because i have heard if the wire is to big then the electric company would have to do something with bus fuses or something. i dont plan on getting them or codes involved where i live is basically red neck country and people seem to go around them i know the garage is wired good because my dad did it and he now lives states away so im on my own now.only thing left to do in the garage is the plugs need screwed in but there are 2 copper wires just hanging in there do i just twist them together and be done.thanks

Scuba_Dave 01-19-2010 05:00 PM

My understanding for ground is 2nd size smaller....so using #2, skip #3 & use #4 as the ground
Do you have fuses or breaker panel in the garage ?
Do you have a pci of what is in the garage ?
You do need ground rods if they were not run before

Here we are allowed to run sub-panels
But for "hot" connections to the meter the POCO & an electrician is needed
So if you have a breaker ahead of where you connect these & can shut the power off you are OK
You do not want to try connecting anything like this live

vinylman70 01-19-2010 05:01 PM

ok called the lowe's told them i needed a #2 wire to run from a house to a garage they said they had a 4 in 1 wire made with #2 copper wire. direct bury no need for pvc pipe. they said it was $1.82 a foot so i guess it will cost right at $300 does this sound like a good deal. then i guess i will still need a 100amp breaker to put in my conecting box on the house. so have i got this figured out or am i still missing anything?also will 12-18 inches underground be far enough i will be running it where nothing will ever run over it other than a lawn mower.thanks for all you help everyone..

tpolk 01-19-2010 05:05 PM

pull a small rope thru pipes as you connect them to your garage for pulling wire later

Scuba_Dave 01-19-2010 05:24 PM

I never run direct burial except on smaller 20a runs
I always run PVC, much easier to replace a wire
And it protects it from damage & digging animals

You'll need to go down 24" to the top of the wire is what I see in NEC table 300.5
Wait........Possibly 18" - I see that for 1 family & only for residential use
As long as it doesn't go under a driveway

vinylman70 01-19-2010 05:25 PM

1 Attachment(s)
the box in the garage is a breaker panel it has a lot of small breakers for the plug ins and stuff like that and has some big ones to wire the welder and air compressor i think they are a 30 and 50 amp breaker. here is a pic of the box on the house it is hard to see but the breaker on top is a 200 which i think is the main to turn on and off the power and below that where i pushed in the blanks is where i guess i would put in a 100 amp breaker to wire the garage correct???

vsheetz 01-19-2010 09:27 PM

I recently installed a sub panel in my 24x30 workshop/garage. Running 240v welder, grinder, drill press, lights, large 240v table saw, chop saw, etc. 120' wire run in conduit. 100a sub panel fed by a 60a breaker in the main panel.

I think you will find it cheaper, easier, and better to go wires in conduit rather than direct burial cable.

Here direct burial has to be 24" down, conduit only 18" - that makes a BIG difference when digging the trench, especially a long one... the bottom is the hardest to dig, and the deeper the bottom the more difficult. Conduit is better as you can add or change easily in the future. Conduit is cheap - use a size or two larger than minimum needed for future additions/change and to make it easy to pull the wires.

codeone 01-19-2010 09:35 PM

Quote:

Originally Posted by vsheetz (Post 385945)
Here direct burial has to be 24" down, conduit only 18" - that makes a BIG difference when digging the trench, especially a long one... the bottom is the hardest to dig, and the deeper the bottom the more difficult. Conduit is better as you can add or change easily in the future. Conduit is cheap - use a size or two larger than minimum needed for future additions/change and to make it easy to pull the wires.

Remember these measurements per the NEC are to the top of the pipe or wire.


1.
Cover is defined as the shortest distance in millimeters (inches) measured between a point on the top surface of any direct-buried conductor,

cable, conduit, or other raceway and the top surface of finished grade, concrete, or similar cover
:yes:

Nicksin 01-19-2010 09:38 PM

The wiring sizing is about right. But... Save yourself some money and get a #4 or #6 ground. There is no need for a full size ground to be run in the pipe. You will have to put a seperate ground bar in each panel for this. a Sub panel which is what you have in your Garage is required to have a seperate ground bar. As for the ground rods once again there is no need to run any bigger than a #6 to them. This will meet code although i am not quite sure ground rods are required. I will have to look in my code book and get back to you. :thumbsup:

Nicksin 01-19-2010 09:42 PM

Also be very careful getting advice from lowes or home depot. I have fun going in there and telling them what i am doing and see what they tell me i need. Its actually quite amusing


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