Underground electric service

[RobA]

I talked to the electric utility today about what they would require for getting electric service underground to my future house site. I wanted to run conduit sooner rather than later (it will be 1,500 to 2,000 foot run). They informed me that they don't want conduit and just want the electric cable buried. They explained that the conduit can provide a path in the event of an electrical fire. Anyone ever hear of this? I thought I read on this site that some of you guys pull electric service cables though an underground conduit.

 

[kennyd]

This is different for each EL company...

My provider, (BGE) does NOT use conduit, but direct buries the EL lines, BUT another company nearby (Allegheny Energy) requires a the homeowner install 3" conduit with a 1/4" rope installed before they will give you a new service.

Bottom line is you have to do what they want...

 

[JB4310]

I've got both, My house which is 100+ ft from the street, has an underground 200 amp service in 3 inch pipe, I had it done when I upgraded 70 year old house.

My little shop in the back is 300+ ft from the street and has a direct burial separate 100 amp service which was done before I bought the property.

I'd prefer pipe but in your case with such a long run, I think that may have something to do with it, that would be a long pull.
Does the power company own the wire and replace/repair if needed?
In my case I payed the initial cost of wire and install to the house but they are responsible for it in the future, would be easy to change with it in pipe. I don't know who would be responsible for replacing the direct bury service to the shop.

As far as the fire hazard goes, I don't buy that reason, does seem possible, but conduit is used everywhere so it can't be such a concern.

JB.

 

[Erik_in_Hoyt]

I put mine in 2" carlon pvc pipe.
a friend of mine with a 1500 foot run had hers done direct burial with "way stations" every 300 feet so if there's a break they don't have to replace the entire run. (that was the compromise with the electric co -- they wanted to do the run above ground through mixed cedar & hardwood "forest"
either way, I suspect you're going to need to do some talking to the power company if only to see why they want to do direct burial. the electrical fire argument doesn't make sense.

 

[Mike058]

Interesting, I'd think they'd be more worried about something cutting the lines and blowing their transformer than a fire in conduit. But I know there's a different set of rules applied to the cable before it gets to the service pole than after. In Washington, the Department of Labor and Industries has to sign off on service laterals. Our utility company had a nice booklet that outlined how everything needed to be done to their (and the state's) satisfaction. You should get an estimate from an electrician for the job. It'll be expensive, but I found that when I priced out the materials for the price I would have to pay, their price wasn't that much more. And when you have a real pro do it, things go real smooth with the utility company and the inspector.

 

[MarkV]

I think I was lucky when we went 200' underground from the last pole to the house. The electric co-op supplied the wire but were very expensive for the trenching, a lot of rock in the area. I dug the trench, 30" deep here", they inspected and dropped the wire in.

MarkV

 

[capi75rs]

Here in central Il, direct burial is common. The electric company prefers that the conduit not be used due to the reason you stated and that water can get into the conduit and freeze causing a big problem in the winter. All they require is that the wires be in conduit where exposed at the pole and house. At these location you put the wire in conduit above the ground and just below @ 18-24", check with your local electric company and/or code for your required depth, and end with a 90 degree elbow below ground. If you have to provide the cable which we have too, make sure it is direct burial cable and not your standard service entrance wire. The wire will state on it direct burial. Also with @ 2000' of run, you'd be time and money ahead to use direct burial.

 

[Jimbrown]

The COOP ran 1200 ft to my house direct burial. The stuff was called direct burial armored conduit. It is about 5 in in diameter and I guarantee it is 10 times stronger than any PVC conduit.I don't think you could cut it with an axe. They used a large radial cut off saw to cut it.

 

[bowhunter543]

Here in northern Wisconsin, they use direct burial for entrance cable.
They say it's because of frost that can go as deep as four feet. They also lay it with wiggles in for expansion.

 

[Cap-n-Cray]

At my property the wire from the pole to the transformer box which supplies 200 AMP service to the house and 200 AMP to the shop was direct burial. It had been there for four years before we moved in. A year after we moved in the electrical company replaced the direct burial wire with conduit and pulled a new wire. They said they were leaking electricity. The wire looked something like big coax cable, single middle conductor with an outer conductor. I think they said it was 7000 volts high frequency. I do have a large transformer box at ground level.

Cary

 

[wushaw]

Mine is @400' in a conduit 36" deep. The guy that did the job said it was 14k volts going through that line.

 

[ray66v]

At 1500'+ you going to be running high voltage, with a step down transformer back by your house.

Perhaps that has something to do with their no conduit requirement?

Although, I'm not sure why it would matter.

 

[tommu56]

At 1500'+ you going to be running high voltage, with a step down transformer back by your house.

Perhaps that has something to do with their no conduit requirement?

Although, I'm not sure why it would matter.

Another for direct burial reason is the dirt removes the heat from the wire better than the conduit.
One thing to watch is the screenings on the bottom of the trench make sure they are flat and smooth and the back fill carefully with more screenings to prevent damaging the wire till you get 1 ft over the wire.

The high voltage and the transformer close to the house is the best choice.
one wire in trench. to the transformer and it will be 100 times smaller wire size at 12000 v verses 220v 3 wire.

tom

 

[ray66v]

Another for direct burial reason is the dirt removes the heat from the wire better than the conduit.
tom

True, but if the wire, and conduit are sized properly, its no problem.

 

[Steve_Miller]

I wouldn't want to buy the wire to run 220Volts 2000'. It would probably be a second mortgage.

Steve

 

[dmccarty]

From the last power pole to our driveway is about 1600 feet. Then up our driveway another 300-400 feet to a transformer. Then another 100-200 feet to the back of the house to the service panel.

All underground. No conduit.

Thankfully I did not have to pay from the power pole to the transformer. Supposedly I was going to have to pay to go from the transformer to the service panel since they had to go around where our future garage will be placed. But I don't remember paying the bill.

Later,
Dan

 

[jbos333]

I had service put in at my "camp" about 2 years ago. Since there was not a "residence" there (yet) the electric co. needed the meter to be near the road......they don't use the remote read ones yet.
I ran 4/0 direct burial 400' to my building for 200A service. It was pulled through 4" flexible corrugated pipe (drainage pipe).
Now I am looking closer at where I want to put the house(eventually). The spot I really like is another 450-500' from the building the service goes to. That kinda stinks because I will need to run another service (high voltage to a step down transformer at the house) because the run is too long for 240v.
Oh well, live and learn. Actually I might reconsider the location of house anyway because that will mean another 500 ft of road that would need to be built, etc.
Also a note to those who want to do it themselves....I went out and bought a ride-on Ditch Witch specifically to do this job, then I priced all the wire, pipe, boxes, posts, conduit, etc. Then I found a guy fom the area who would do the entire job, get it inspected, etc. for $500.00 more than what I would have spent on the materials!
I have used the trencher for other stuff anyway, but sometimes it's money well spent to have a pro do it.
So, I guess my point is, try to plan a little better than I did! Although I'm still happy I have electric service, I might have done it a little differently....

 

[JB4310]

At 1500'+ you going to be running high voltage, with a step down transformer back by your house.

Perhaps that has something to do with their no conduit requirement?

Although, I'm not sure why it would matter.

So I take it this would be the only way to go that far of a run, using a transformer? makes sense.
So only 1 wire is needed to feed a transformer, I know the 2-110V leg split is done at the transformer, but what about ground, is that all done at the site of the transformer, with no ground going back to the grid?

Also anyone know how small a wire could be used to feed transformer 1500 ft from the road if primary was average 15-18KV?
Are those single house transformers expensive or prone to any problems?
And how about what size cable would be needed to go 1500 FT and deliver 200 Amp service.

Just curious, JB.

 

[MikeD74T]

RobA, Ask your power company who's going to pay for the wire if it fails -either direct burial or in conduit. Then ask who's going to pay for the digging if you don't go with conduit. Ask who's going to repave the driveway if needed, etc. I'll bet the price of the trench is far more than the conduit. Also consider whether this will be your problem or the next owners.
Some people buy life insurance, some don't, everybody dies eventually. Conduit is insurance.

As for fire path -I work at a nuclear power plant & a major part of my job is tracking fire barriers in ducts, conduits, etc. The ability of a conduit to propogate a flame path is measured in pipe diameters, in other words beyond a certain number of pipe diameters the flame path will deminish completely. A fire would have to be within a few feet of the end to be adversely affected and even then the termination point -meter box, etc- is rated for fire. Their fire path excuse is not valid. MikeD74T

 

[Pilot]

In '92 when we built our house, the phone company plowed in both the phone & power lines at the same time using an orange plastic conduit.

They showed up at 7, the power guys talked to their shop steward for half an hour because the phone guys were non-union, then they got to work. Dug a pit on each side of the road, pushed the wires across, then started plowing, 1,200 ft. Done by noon. Slick.

Cost was about the same for poles vs. plowing except I would have had to dig the ditch if the phone co. hadn't had a plow. Since we were going thru forest, I wanted it underground; we get enough power outages as it is.