# Aiming to get electricity for my cabin via underground burial. Few questions

To introduce my situation, I'd like to preface by saying I built a 12x20 cabin on some family owned land for me. When trying to get electricity out here, the electric company said either A. They would have to set a new pole by the dirt road (100 ft. away), which would cost 1800\$, or B. I could do underground burial to a pole in an opposite direction (behind me) that is about 160-180ish ft. away. They said if I go with option B, all they'd step in to do is put a meter on that pole, I'd be responsible for everything else.

Given those options, I'm under the impression option B with underground burial is the money saver route for sure. I can't imagine them setting a new pole 100 ft. away for 1800\$ (plus w/e other costs) is going to be cheaper.

Now to fill you guys in on electrical expectations/usage. My demands will be very low. I won't list every single appliance, but in summary I'll most often be using a computer, 2 monitors, digital piano, speakers, microwave, hotplate, 2 LED bulbs, 6000 BTU AC in summer etc. (Usually, not all of this stuff will be plugged in at one time), and even if it was, I'm going to say this will only draw 2500-3000W combined. There is no 240V outlets in this cabin, and no demanding appliances like washers, dryers, electric stove tops, water heaters, shop tools, etc.

With the backstory and power expectations/draws out of the way, I'd to know what wire I should be on the lookout for? I'm a total noob, but was recommended by someone else that Aluminum 2-2-2-4 MHF wire is what I should get. I was using the Southwire's voltage drop calculator and assuming I input everything correctly, this is what I got "Voltage drop will be limited to 2.64% or less with a 2 AWG aluminum conductor delivering a total of 30 amps on a 120 volt single phase system for a distance of 180 feet"

(As stated before it's unlikely I'll ever draw 30 amps, but I put it in the calculator just to see) I put in 40 amps just for the hell of it, and it said voltage drop would be 3.52% which to my understanding is still healthy?? I was reading NEC recommends 3-5% ? ? ?

I'll be more than happy to provide any other requested information I might have forgotten that would help you guys assess and determine my needs.

• Do you have the gear to dig a 180ft / 65 metre trench to a depth of 3-4 feet/90-120cm ? A shovel is not really practical unless your time is free. Commented Aug 22, 2022 at 3:12
• Solar panels + batteries? Commented Aug 22, 2022 at 8:17
• @TooTea - depends a lot on the soil and how many rocks and tree roots are in the way. Renting a ditch witch for a weekend will be pretty cheap. Commented Aug 22, 2022 at 13:39
• With the underground option, you will be responsible for repairs between the meter and your cabin. With the pole 100ft away as described, the electric company will be responsible for an outage between the pole and the service entrance on your cabin. I frankly don't like the idea of the underground burial as a DIY project. Commented Aug 22, 2022 at 14:10
• Don't make the very expensive mistake of thinking "I'll never have any need for more than this amount of power out here". A larger panel with far more circuit spaces than you think you'll ever need will cost you \$\$ today vs a "just what I need now" panel that'll cost you \$ today. However, when the time comes that you need to add one more circuit than that el cheapo panel can support, it'll cost you at least \$\$\$ to replace the darn thing. As they say, go big or go home. Even if you don't use 'em, it's a selling point in the future. Commented Aug 22, 2022 at 14:54

If you use 2-2-2-4 then you are actually getting 240V, or 2 x 120V. So your current usage, if reasonably balanced, will actually be half that. If you use 30A @ 120V = 3,600W and it is reasonably balanced then it will actually be ~ 1,800W = 15A on each leg. So with that size wire and that type of service, voltage drop will be a total non-issue.

Burial depth can be a huge issue. Depth can be (depending on where you look, and possibly depending on jurisdiction) anywhere from 6" (metal conduit) to 12", 18" or even more for direct burial. It may be worth looking at conduit - e.g., schedule 80 PVC. Yes, conduit costs. But it allows for future upgrades (if sized correctly) and lets you dig a lot less. That isn't a big deal for 20 feet on flat open ground. 160 feet through the forest it may be a big deal. If you use conduit then you can use (should use - it will be easier) individual wires instead of 4-wire cable.

• Pretty sure it's 24" minimum cover for direct burial, (then there's the whole roads and driveways parts, if applicable) but direct burial is a fool's game (trenches are expensive, conduit is cheap, rodents and rocks both like to ruin direct burial cables, and then you get to dig the expensive trench again.) Commented Aug 22, 2022 at 0:58

With the backstory and power expectations/draws out of the way, I'd to know what wire I should be on the lookout for? I'm a total noob, but was recommended by someone else that Aluminum 2-2-2-4 MHF wire is what I should get. I was using the Southwire's voltage drop calculator and assuming I input everything correctly, this is what I got "Voltage drop will be limited to 2.64% or less with a 2 AWG aluminum conductor delivering a total of 30 amps on a 120 volt single phase system for a distance of 180 feet"

Whoops, you entered 120V.

The USA is a 240V country. Really.

The video will describe how we supply 240V with a center tap, and get two banks of 120V out of it. It's a leftover from Edison DC power, but Edison wasn't completely wrong. It really does help with voltage drop, because you distribute your 120V loads on both poles. Thus voltage drop is immediately halved or better.

The result of this trick is you must enter 240V when using a 4-wire feeder as you plan. Honestly, given my experience and your distance and #2 feeder, I wouldn't even bother calculating voltage drop. It's just not going to be an issue.

Your choice of wire is spot-on. It's an ideal choice because it's popularly used for 100A services to mobile homes (MH, hence the name). This puts it at a cost/availability "sweet spot". It is only good for 90A on feeders, but we can use a Code trick to get 100A out of it for service to an entire dwelling.

(As stated before it's unlikely I'll ever draw 30 amps, but I put it in the calculator just to see) I put in 40 amps just for the hell of it, and it said voltage drop would be 3.52% which to my understanding is still healthy?? I was reading NEC recommends 3-5% ? ? ?

NEC is silent on the question. Most wise people recommend 3-5%. However your voltage drop will be half what you think it is, so you'll have 3.5% at 80A, which is the max you're allowed to plan to draw from a 100A service.

Remember it is 100A @ 240V, so it is 24,000 watts, not 12,000.

However, 100A services are largely obsolete. These days the power company wants to give you 200A. You will need a disconnect at the meter (small 200A main panel, or meter-man) with a 100A breaker in it feeding your #2 feeder. That will be fine.

If you think you might someday dig or plow near the cable run, consider using galvanised pipe to put it in. Expensive, but so is accidently cutting or ripping up the line.

• Galvanized pipe, no, nope, don't do that. Rigid electrical conduit (which looks like galvanized pipe to the casual observer, but is actually different in important ways) yes, certainly, and that only has to be buried 6" to the top of the pipe if not under a road or driveway. Also the important roll of "buried electrical line below" tape to bury above it. Commented Aug 22, 2022 at 0:55
• @Ecnerwal A bit of googling says that the conduit has a smooth bore to prevent snags/nicks (which makes sense), but also says that it has different threading such that the conduit is not water tight. Wouldn't you want your conduit to be water tight? I get that the cable is already waterproof/meant for direct burial, but any nick in the cable would be disastrous if it were surrounded by water. Wouldn't you want that second layer of protection? Commented Aug 22, 2022 at 12:10
• All outside conduit is defined as wet, and usually meets that definition. If the threads are perfectly sealed, condensation will still fill it with water. So leaky joints actually don't matter. Not putting nicks in the insulation is indeed one of the important differences .vs. water pipe. Commented Aug 22, 2022 at 13:11