General questions about burying feed to the garage

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Old 08-02-04, 06:19 PM
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General questions about burying feed to the garage

I'm going to bury a 200 Amp feed about 100 to my garage. This is overkill but not by as much as you might think. It's a two story garage that with a shop downstairs and an apartment upstairs. I will probably set it up for 150 Amps but I want the line in the ground to have plenty of capacity because I sure don't want to run it again if I switch to electric heat or something like that.

Anyway my question is more than just electric. I need to run everything but the kitchen sink out there. Electric, gas, water, sewer, cable, phone, switch legs & networking. The only thing I know is that I can't put water in the same ditch as gas but what can I bury with the electric? Can I put everything in one ditch with the water & sewer in the other? Is there one type of contractor that would know all of this? Any normal GC? Thanks for any advice. I'd like to get this stuff in the ground before the frost sets in.
 
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Old 08-02-04, 06:29 PM
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You cannot put anything with the electric. You would end up getting lousy signals on the low voltage lines. Separate the electric from the low voltage by at least one foot.
 
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Old 08-02-04, 06:53 PM
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I don't have a whole lot of choice here. I can get the 1 foot by burring one set deeper than the other. The property is very narrow with not many places to separate the cables. I'm in the low voltage business so I'll make sure that I use cables with good shielding and run fiber for the network. What does the NEC say about cables and gas in the same hole?
 
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Old 08-03-04, 03:41 PM
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You need to keep the electrical power away from everything else by at least a foot. Same for gas (and apart from the electrical as much as possible). If you can dig a trench about 30 inches wide and lay the electrical on one side, the gas on the other side, and the rest down the middle, that might be OK (but I'm not sure if anything else, such as phone and water, need any further separation). The further the better.

Depth separation I would say is a bad idea. If you need to dig something up, you'll be making a big mess of something else, most likely.

And lay some distinctively identifying marker tape above each of the separated runs in case you forget which is which in case you ever do have to dig something up. You don't want to be digging up the water line only to find you get gas or electric.
 
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Old 08-03-04, 07:08 PM
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I'll have to go back and look at it again. There is a good 15' stretch where separation is not possible. There is always more than one way to skin a cat. Sorry kitty. The water and sewer will be run right up the middle of theproperty so perhaps I will have to run all the low voltage with that run and the electric and gas in the other run. Not exactly what I want to do but better than having noise on my phone lines.
The thing is I am forced to run low voltage next to high voltage in homes all the time and never have a problem as long as the wire is good and the terminations are done properly. Does something change with buried wires instead of free air?
 
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Old 08-04-04, 07:39 AM
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When the utility ran the power and phone lines to my property they didn't separate them at all. The phone line is right next to the 200A AL conductor. It's a heavily shielded phone line with a metal clad, and so far it works fine.

There is no need to separate fiber from anything, fiber is not really influenced by anything that runs through that trench.

I'm also not aware that you have to keep a minimum separation between a water line and anything. The water line will probably be plastic anyway, and even if it breaks all that will come out of it is water, which is already present in the ground anyway. Same is true on the sewage.

Where I am freezing is an issue, so we bury the water ans sewer lines 5' down. The electric is burried 2' down, and everything else (gas, phone, network) about 12" down.

The only bad thing about burrying everything in one trench is the fact that if one line breaks, you'll probably damage all of the other lines trying to repair the one broken line. If freezing is not an issue then the water, gas and sewer lines can be burried at a much shallower depth. In my area (central WI) the gas line (copper) and low voltage lines (phone, etc) only need to be burried 6" below ground. Check with the building inspector to find out what the minimum depth requirements are.

We usually try to keep network lines away from AC lines by at least 6", but we had time in which we had to run them right next to eachother for about 100' withought any noticeable signal loss.
 
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Old 08-04-04, 08:46 AM
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the gas company requires that no gas line be in the same ditch as a water line. They said that statistically the water line has to be dug back pretty often and they don't want to rupture the gas in the process.
My intention is to run a 12 pair shielded phone line, a few direct burial cat5, a single fiber and two or three Quad shield direct burial RG-11 coax. I will look at the situation again but putting the low voltage, gas & electric in the same trench works very well with the layout of the property. The water and sewer are better served in a different trench anway as they come in and leave on the other side of the house from the other services.
 
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Old 08-04-04, 08:56 AM
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You may want to bury a single 2" PVC or poly pipe, and pull the low voltage lines through it. That way you can easily add another line, or replace one line if it will go bad. Why so many low voltage lines anyway?

Also, you'll need a 4 wire feeder for the electrical line.
 
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Old 08-04-04, 09:08 AM
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Originally Posted by trinitro
You may want to bury a single 2" PVC or poly pipe, and pull the low voltage lines through it. That way you can easily add another line, or replace one line if it will go bad. Why so many low voltage lines anyway?

Also, you'll need a 4 wire feeder for the electrical line.
Actually the PVC was in my notes, I had just forgotten about it. My plan was to do both, direct burial and PVC for any later additions. I just have to see what it's going to take to get all of this in the ground. The second floor of the detached garage will be my office-private showroom for my custom audio business, as well as my personal home theater. So I have to go complete overkill to make sure that I can send whatever signal I need between the two buildings for any home automation I may do down the road. I've got four phone lines, cable & HD satellite on the way that I will have to distribute right now. Hopefully as everything goes IP based I will only end up using the fiber link when it's all said and done.
 
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Old 08-06-04, 05:11 AM
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Have you considered running your service lines and/or low voltage lines overhead. This obviously has less aesthetic appeal, but might solve some of your problems
 
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