Underground electrical service for cabin

[flusher]

I am in need of some advice. I know nothing about electrical things. Here is my application.

I am going to drop off of an electrical service pole that the local electrical company is going to provide. I am running an additional 400'-0" of underground to my cabin site. The burning question is as follows.

What size wire do I need?

I have been told that 4 wire mobile home direct bury wire will be ok. I am going to have central heat and air, electric stove, washer, and dryer in the new cabin. Any help would be great.

Thanks,
JDW

100amp or 200 amp service?
My 200 amp service uses 4/0 copper wire in PVC conduit (300 ft run from utiity pole to my outside load distribution center).
My preference is copper, but aluminum is cheaper and gets the job done. You just have to be aware of corrosion problems with aluminum connections and do the installation properly to prevent this.
I strongly recommend conduit to eliminate the problem of rodents chewing up the main power line to your place.

 

[Illini22]

4/0 al. with 2/0 nuetral will get you 200 amps all day long at 400 feet. If your concerned use 350 with a 4/0 nuetral. Menards has 4/0 for less than $2 per foot. Don't want to start a debate on direct bury or conduit as you will get people telling you conduit is the only way to go. I've been installing overhead and underground for over 25 years, both direct bury, in conduit or conventional
Underground in duct packages thru manholes. For a simple house service useing urd al. Cable direct bury would be by far the cheapest and many, many times easier for a homeowner to accomplish. It is an industry wide used practice to install direct bury, no matter what you hear ( so is conduit). The hard plastic insulation is very very durable( sharpen your knife or get a urd 4-way skinner). In the unlikely event it does get hit, a machine will go thru conduit almost as easy as the conductors unless you use rigid (unlikely). The major difference on a "hit" is your damage will be limited at the location of the hit for direct bury, a few splices and 5 feet of cable. Unlike a "hit" in conduit, repairing the conduit and repulling the repaired cable will be your easyest part of job. Replacing your service entrance , meter cabinet and the bill fron the utility for replacing the transformer when the secondary bushings get yanked out of the can will be major expense. I could go on and on but I'll let some others chime in.

 

[EE_Bota]

I have designed projects for the rain forest, for NYC, and for the arctic circle. They were all different. Update you profile to tell us roughly where you live, not exactly where you live. Then someone might chime in and say they know your code requirements, or even that they work for your power company and might call in a favor on our behalf. You just never know.

 

[tommu56]

With your distance it migth be cheaper to put the transformer close to the "cabin" then run high voltage to the transformer and the short hop to panel. just one little wire for the HV.

tom

 

[smfcpacfp]

Like others have said, talk to the power company engineer first and the electrical inspector. Both were helpful to me when building my pole building. I decided to go with a second service since I planned to have a shop in my pole building, thus needing to have an electrical inspection before the electric utility would hook up the service.

The run from the transformer to the house was 300' or so and another 200' to a pole from which I ran the last 60' underground (conduit required by electrical code). The utility engineer decided that the run from the transformer was too long of a run, so they moved the transformer closer to my house. You would likely have the same problem (too long of a run from the existing transformer).

 

[cisco]

Some fine replies, and I have little to add to Jinman's. YOU need to calculate the max. load your dwelling is likely to require, or have someone well qualified do such for you, and then it's a matter of local codes and what your power company will do. I've recently pursued to 2 remote wiring needs with different strategies. I've a dock on a 400 foot walkway (don't ask), and the base of that walkway was 600 feet from the powerpole for my well and irrigation system. So, I was looking at laying wire 1000 ft to achieve a 30 amp service at the end of the dock, with boatlift. There a number of sources for estimating wire size (one of which was kindly attached by a prior poster) requirements for specific amp needs at distance, both for aluminum and copper. Anyhow, my "co-op" power company will run wire and supply a meter for a base fee of $7 per month (plus usage and the wire cost for them - it was ~ 1/3 the Lowe's price for wire, and the conduit and trenching were done gratis - incredible). Usage on my dock is minor, so it made sense to have them run the 600 feet to the base of the dock. From there to the pierhead was on my dime (well, just a tad more than that). OK, second project was 30 amps for a new tractor shed about 300 feet from that same well/irrigation power pole, and I put in the run myself, using appropriately sized wire (in my case, 4 strands of 4-0 copper with PVC conduit in an 18" trench - a day long project - I ALWAYS run 240v to the circuit box, as it only costs one more wire), and while I was at it place a water line just below the wire conduit.
So, what are your amp needs, how long is the "run" to your place of need, and what will the power company do, and at what cost?

 

[mojoinco]

Here's a sample construction guide from my electric company (click on the 'builder developer handbook' link). New Construction/Builders

Unfortunately, it doesn't list the current versus distance ratings, but any electrician worth his salt can figure this out based on your service needs. As I recall, conduit requires a thicker cable than direct burial due to heating affect (versus higher heat sinking from direct burial).

Is it worth it to pay for a couple of poles? Any particular issues with the soil (rocks, heaving, etc)? Also, any future fencing or plumbing plans? The trade off for direct burial that far is any future plans have to work with it. I have a mixed setup, with a central distribution pole that has the overhead power come to a main breaker/distribution panel and meter, then off to each building underground. Much smaller cables, shorter distances, no power cables underground near the property line or driveway.

One advantage to paying for the meter being closer: long term, they get to maintain it.

 

[rharkins]

My cabin site was around 800' from the main high-voltage line on the road. The local electric coop would install poles and overhead from the road to the site for free. I would have to take down enough trees to clear a 40' wide right-of-way. Since we were in solid timber, that was out of the question.

I ended up burying high-voltage cable from the road to my site. I had to dig the trench and buy the transformer which would sit on the ground at my site. My septic system installer dug the trench for me very inexpensively, since he was already on site. The transformer cost $1000. The electric company supplied the cable and the meter post. I only had to run UF cable from the meter post to the cabin, about 10'.

We love the result, because the heavy timber blocks the view of our site from the road. Plus, we have all the electricity we'll ever need right at the site, which will eventually include our home.

 

[RickB]

"Here" the utility would almost certainly require that primary be run closer to the cabin and a transformer placed remote from the existing primary lines. Code will dictate the size of the service and the incoming conductors. "Here" a 200 amp service would be the minimum allowed. A demonstrated lower demand would fall on deaf ears. I won't have AL conductors on my property.

 

[Illini22]

While I would never install al. Inside my house. It is used my most utilities for sec. And primary. The leads coming out of the cutouts, transformer bushing and other taps are usually copper and then the wire or cable is tapped onto the leads. If you have utility owned lines on your property than it's probably al. Unless it was installed before 1960. Another benefit of al. Is that it will corrode fairly quickley at the hit and you will halve a part out or half power letting you know. With copper it will just keep on pimping and may be years before it could cause an outage, but if the hit is downstream from the meter it will register as load and really up your utility bill