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.