Underground electrical service for cabin

[jdw96flstc]

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

 

[AlanB]

Have you spoken with the engineer for the power company?
Mine has been extremely helpful in telling me my options and making suggestions on better ways to do things. For me, placing the meter was important as it was who would pull and pay for the wire, by placing the meter on my barn, I had to run the conduit, but not pay for the wire (which is quite expensive) look at your different options with the power company and I bet that will help you decide, and that guy will know the sizes you need to use of wire, conduit etc.

 

[Western]

I was measured yesterday for a 300' run 200a service for a shop.

What the electric supply/install company (not the electric power company) recommended for me was 4/0 AL URD, or Aluminum direct bury. quoted at $1.75 per foot, wire cost only.

 

[hr3]

Cabin.. 20'+20'...or something like 60'+80'..... You will need to know your loads before you can figure the voltage drop.. "Size matters" Like Alen said talk to your utitily company and ask there advice,,,

 

[JB4310]

I've got a small shop behind my house that has it's own direct burial service.
It's about 350 ft run, the shop has a 100 amp panel and the wire is 4/0 AL. I didn't put this in but I think this size wire is capable of more amp capacity at this distance.

My house is 100 ft in 3 inch pipe, 200 amp service and also 4/0 AL.
I did have this service redone when I renovated the whole house 5 years ago, so I know this is up to the latest standards and codes.

Make sure you don't let the wire insulation get damaged and back fill with sand around the wire to prevent future damage.
I had a failure on one leg of that DB run caused by a tiny nick that let water in and oxidized the wire to a white powder.

JB.

 

[SteadyEddie]

AlanB is right, contact your utility co. about this. They will explain your options as well as what you pay for/install & what they'll do. I work in the "new business" dept. at our utility & do this all the time. We would let you run 4/0al a maximum of 250' for a 100 or 200 amp service.If you installed a larger conductor - 350kcm, we'd let you go as far as 450'. Every utility has different specs & rules, so the earlier you talk to them the better, since they won't hook it up if it doesn't meet their standards. Also, the utility can insist ontougher standards than national or state codes.

 

[Mike058]

Don't automatically think your going to save a fortune doing this yourself rather than hiring an electrician. I was going to do a similar job and when I compared the cost of the material to the cost of having a pro do it, it wasn't that huge a difference. It's going to be crazy expensive anyway. The other thing I'd note is the distance. When I had my power put in, my utility company provided a very useful pack of information. Wire size, where to put the meter etc. I'll quote something out of it "Secondary service distance for a 200 amp service with a conductor sizing of 4/0-4/0-2/0 AL USE shall not exceed 218 feet of cable length. The same service may be fed by 350-350-4/0 AL USE cable up to 341 feet." The thing I wanted to point out is my utility wouldn't hook up to a 400' run. You should contact them, ask if they have a packet for homeowners and check it out. Get a quote from an electrical contractor (a couple if you can) and compare that with the cost of just the materials. Having a local pro do the job will greatly increase your chances of having a successful inspection to. Not sure about your neck of the woods, but around here, they won't hook you up until Labor and Industries signs off on the job.

 

[rambler]

Is there any way to get the utility to bring the powerlines & transformer closer in to your cabin location? That likely will be a cheaper option.

Long runs of 240v take very big wires - on your nickel.

I like to use this voltage drop calculator, some say it is a little aggressive & lists a bigger wire than needed. I donno, 5% drop is allowed, but 3% is a better standard for the feed wire as there will be more loss inside the building(s).


Voltage Drop Calculator JavaScript

Says you need 250cmc aluminun wire for 100 amp service at 400 feet.

Or 500mcm Aluminum wire for 200 amp service.

The 4/0 wire some mention would give you an odd 80 amp service wire.

Going to build any more buildings, a small shop, a horse barn, have a garden, or??? How big of a cabin is this..... Future expansion???

Sure is hard, and not even allowed in some places, to have less than 100 amp service to a dwelling any more these days. 200 is better.

If you could get the utility to place the transformer about 50 feet from your cabin, you would only need #2 or #4 wire for a 200 or 100 amp service - big price difference to you!!!!

Voltage drop is the electricity running through the wires is being consumed to heat up the wire. It is worse on longer wires, and bigger amps makes it worse. The shorter you can keep the wire, the less of a problem. You get to pay for that electricity used to heat the wore, and it can become dangerous if the wire gets too hot. The bigger danger is electric motors - they do not like voltage drop, and you will shorten their life if they get too much voltage drop. So - you can't just ignore this, or think it is some stupid rule. It's based in the real world. The longer the run of 24v wire, the thicker it has to be.

--->Paul

 

[Gary Fowler]

I agree with everyone, get a pro. Sometimes you get a real idiot with the power company that hooks up the wires. My son is a licensed electrician and installed the power cable (years ago) to a mobile home from the pole to his house. He used galvanized conduit, covered it with Red concrete and the power company rep wouldnt hook it up. Wire sizing was correct. HE quoted a power company rule "Wire must be direct burial or installed in PVC conduit so since it is in ridgid metal it doesn't meet our requirements." OF course my son raised a fit even showing the guy in NEC code that ridgid is better than PVC but didnt matter. My son then called the electric company, they sent another more experience guy out the was well satisfied with the installation. and hooked it up. He even called the other guy an idiot.
I am in process of building a house and originally thought about running the wire myself, but then thought better of it. There is a phone cable and a water line that I have to cross so I would rather pay the electric company a fee to install it and if they cut the phone lines or water line, they have to repair it. I am sure that if I cut a trunkline phone cable that would cost me much more to repair than what I have to pay in difference to have it installed.

 

[jinman]

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

JDW, if your "cabin" has all that stuff, I'd love to see what you call a house. Wow! That's gonna be a nice cabin.

One important thing you left out is where you are located. Local codes in my rural county in Texas are a bunch different than in other places. The weather and the local codes have a lot to do with the requirements; although, except for burial depths and techniques, wire types and good electrical practices are probably very nearly the same no matter where you live.

You need to first calculate your maximum load by finding the current draw of each of your electrical appliances, lighting, and HVAC. Add them all up and figure the heaviest load possible at any one time. For example, you'd never have to calculate electrical heating and air conditioning at the same time, but you could surely have a water heater, washer, dryer, and electric range, refrigerator, microwave and electric heater all running in addition to lights and maybe TVs, computers, and electrical tools. Will your septic system be conventional or aerobic? What is your water source? Will you have to run a well pump as well?

You need to add up all of this and then you'll be able to tell anyone you go to for advice just how big of a load and the distances between the meter and your loads. From this info they will be able to calculate the type of service and size of wire needed. Without this info, all you'll get from us is a bunch of personal anecdotes. Nothing will be accurate to your exact situation.

 

[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