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I'm in the process of converting three barns into houses. Two of the barns are located 50 meters away from the main power pole.

I'm considering two options for getting electricity to the barns. Option 1 is to install two meters at the bottom of the pole and run my own cable to the barns, which would involve a cable run of 2 x 50 meters.

Option 2 is the more conventional approach of having SSEN (Scottish and Southern Electricity Networks) install the meters in the barns and run the cable (which we would dig trenches for). I'm waiting on a quote for this option.

I'm concerned about potential power loss over the 50 meter cable run for Option 1. If there is significant power loss, I would be paying for electricity that wouldn't actually reach the barns. SSEN has provided a quote of £3k for Option 1, but I expect Option 2 will be more expensive.

BBC Basic
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    For power loss in a long run of wire/cable most people just use larger wire gauge. For 50 meters will probably just be one gauge larger. There are tables online to find find the right gauge for the distance and the amount of power/amps used. – crip659 Mar 24 '23 at 11:35
  • Most people are also more concerned about how the power lost affects electrical equipment than how much it costs. Motors will turn slower if the power lost is too much, maybe even heating up too much. It does not matter if the meters are close or far away, it is the size of the wire for the distance. – crip659 Mar 24 '23 at 12:46
  • If you have to dig the trench either way, and if you implement Option 1 correctly so there is not unacceptable power loss, then the only differences between the options are cost, appearance and convenience, none of which are topics for this site. IMO you should get quotes both ways ... if there's a big difference the choice is obvious. If not, think about the look and what your buyers/tenants might prefer. – jay613 Mar 24 '23 at 14:16

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Not sure what your question is exactly. In my humble opinion, option two would be the way to go. The power company would be responsible for service to the meters at each location so any voltage drop problems would be their concern. They would also be responsible for any cable failures between the pole and meter locations whereas if you run the cable, the problem is yours.

JACK
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Option 2 is the better, as SSEN will automatically use the correct cable for the supply to a dwelling including earth etc. Then you get to sort the distribution board etc as usual - or your electrician does.

If you do option 1, then you will have to sort cable, termination, switching and earthing to code and then sort the distribution board etc

If you are digging the trenches anyway, then get them to sort to point of use. Where is barn 3 though…

Solar Mike
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If you get separate electric meters, you will have separate electric bills. I don't know how it is elsewhere, but in the US we have power companies grasping for ways to pay for the infrastructure costs associated with new energy tech - rooftop solar and the like. Their favorite trick is to start charging a flat rate merely for having a service /meter. Thus I would advise "1 service per property" simply as a defense against such schemes. Carrying power 50m isn't a problem.

I'm concerned about potential power loss over the 50 meter cable run for Option 1. If there is significant power loss, I would be paying for electricity that wouldn't actually reach the barns.

There is an answer for that, and it isn't guessing. It is a voltage drop calculation. Fortunately many web sites exist that will do the calculation for you. I can tell you from having done many of them that it won't be significant - for 240V feeders I don't even bother doing voltage drop calcs until at least 170’ (52m) because the answer is always "the normal wire size is fine". But European spec wires tend to run a bit smaller for the same ampacity, so you should do the calculation for yourself on the minimum and a couple of larger sizes.

Remember that voltage drop is based on the actual current on the wire based on draw right now: it may be on a 50A circuit, but the physics forces which cause voltage drop don't know that :)

Since people rarely load a feeder beyond 80%, iI went with 40A and got (sorry for the odd units but my handy calc only speaks AWG):

  • 4% (3.95%) using 8.3 mm2 wire.
  • 2.54% voltage drop using 13.3 mm2 wire.

Again assuming 40A actual draw.

You can leave this to the power company, in which case you'll get Hobson's Choice on wire size, and if it's on your side of the meter, you eat the loss.

Also, I don't know if this is relevant to the UK but think about electric cars.

Harper - Reinstate Monica
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  • Hm. Interesting point about per-service fees. They aren't huge here (Eastern MA), but they do add just enough that my solar has never quite produced a month where the utility actually owed me money, and over years they'd add up. Of course then you're getting into needing your own meters if you want to divide up the bill, and I presume that if you actually sell off any of these houses the new owners will want their own services anyway... – keshlam Mar 24 '23 at 22:45
  • @keshlam yeah, assuming the property even can be subdivided. Probably need permission from the laird... – Harper - Reinstate Monica Mar 24 '23 at 22:46