Can anyone tell me a) whether it is possible and b) approximately what it
would cost to have an overhead electricity supply converted to a buried
We are planning an extension to our house in Cambridge, UK. The single
phase, mains supply currently runs overhead from a pole in the road to the
eaves; a distance of approximately 15m. The cables will have to be moved
anyway and replacing them with an underground cable back to the pole would
be a neater solution.
Anything is possible...
I asked BT a good few years back about getting our overhead line buried,=
probably 40m of trench but 10m under a road. Cost was > =A31000, I didn'=
take them up... Digging holes under roads is not cheap.
Yes. It cost me £18000 in 1999 to remove a 1km stretch of 11KV going
across the top of my house..that included relaying it all underground,
including moling under the road, hooking it up at one end to an existing
undergrounded section, and putting stays and downlead on the pole at the
other. In addition I got a substation all to myself. Instead of a pint
sized transformer up a pole.
Th real cost was £30k, but Eastern Electricity paid £12k of it themselves.
They estimate for 11kv stuff, £30k per kilometer.
Mmm. Does it have to cross the road?
If its only 250V stuff,I dug my own trench and laid my own cable
(supplied by powergen) from the new substation to the house.
If you do all that bit, and leave then with just a junction to do and a
bit of kerb digging, might be less than a grand. WELL worth it.
Yes. Thats the killer.
Need sort of permission, then loads of blokes stranding around doing sod
all, until the one with the jackhammer turns up, then they all look busy
for half an hour a day, when the gaffer comes riound, and a week later
its done,. Then the little men with the road rollers come along and the
same process happens..to re-surface.
Rather depends on what is involved, but assuming you are looking at a
standard single phase supply......
If you can excavate and backfill the trench all the way to the pole,
that'll reduce costs quite significantly, at today's prices probably
£200-£400 to pay.
Remember though that you can only excavate on private property. There are
all sorts of problems with private individuals wishing to excavate in the
If they do all the digging, expect at least £2K-£3K, if there's much
digging out in the footpath or a road crossing, you can probably double
that. Quite a few years since I did quotes for that work, and I've just
guestimated current figures. Colin Wilson may be able to come up with
Whatever you do, ask for a breakdown of the estimate.
Other possibilities, if the house is an older property, and the o/h supply
has been there for *many* years, it may be reaching the end of its life
(particularly the cables that enter the house). Do they appear to have a
woven cotton cambric type of covering, usually a dark reddish brown colour
- you may be able to see them close to the meter postion. Alternatively, if
you have an eaves bracket that is pulling heavily on the fascia, then you
may be able to spin them a tale about their equipment damaging you
property, but the overhead cables really do need to be obviously bar tight
with signs of the bracket pulling away anyway. In either case you may be
able to negotiate for them to do the work FoC.
That distance they would use a Grundomat Mole, not do a trench. EDF
quoted me £1100 to bring 3 phase from a pole transformer on my land to
a workshop 50 foot away, and again intended to mole not dig a trench.
But he's not talking about 11kv
He's quite clearly said "The single phase, mains supply currently runs
overhead from a pole in the road to the eaves; a distance of approximately
15m." Your comments are *totally* irrelevant.
Oh, I remember, you like to tell and re-tell ad infinitum how you paid £18K
to have 1km of 11kv o/h undergrounded and you now have your own substation.
Total boring bollocks.
I quoted the cost of doing a local underground installation as well.
The cost of trenching irrespective of what's laid in it is 30 grand a
Which is 30 quid a meter, roughly.
The hire of a mini digger to do 15 meters, cost me around a days hire at
£100, say £100 of my time, plus a day to lay, cover and make good. Say
300 in all, and probably about £100 of cable when alls said and dine,
then the meter needed reconnecting..
I thing £30 a meter, plus road transit costs, is a very decent estimate.
Your credentials for making that completely erroneous claim?
I worked in the industry as an Electrical Engineer (Distribution). I
covered all aspects of the work, planning, construction, operation and
maintenance, domestic service installation.
I know from 35 years experience what I am talking about. You are basing all
of your comments on your one oft repeated experience. Oh, and by the way,
you appear to be factoring in the cost of establishing a ground mounted
substation in making your claim of £30/m for cabling, the cost of
alterations to and the dismantling of the section of overhead line,
wayleaves, legal fees, I could go on, but it would be much better if you
stuck to things you *do* know about, whatever they might be, rather than
things you *think* you know about.