Maximum distance to house from transformer

[DaveC]

Hi All.
We have just purchased some rural land in northland. There is a Northpower powerline and powerpole (and transformer I think) at one corner of the site, but the potential residential building site is about 1km away up the gravel right-of-way.
What is the maximum distance that a 240V line could be run to a house? I'm guessing that 1km is too far?
I assume that the Northpower line is High Voltage (2kV? 6.6kV? what is normal?), so another option is to run a HV cable up to nearer the building site and then transform it down to 240V. Can an HV line be undergrounded? How expensive would this be for 1km of undergrounding etc?
Thanks! Dave

[gregmcc]

Hi Dave,
From the content of your message it appears you are not an electrician?

There are a lot of factors that limit the distance, such as how many amps to you want available, type of cable, basically the limit is how much you want to spend!
The Northpower HV could be 11KV or 33KV, there is no reason why the HV could not be extended, but you would have to contact Northpower to price this up.
Either way, you need to engage an electrician and Northpower, it is not going to be cheap, I would expect 6 figures ($100k+) if you need to get the HV extended. You may be better going off grid, generator/solar, but this is where you need to get an electrician involved.

[DaveC]

Thanks for your reply Greg. Yes, we are certainly considering the off-grid option. It sounds like it would be cheaper anyway. In general, is it possible to underground HV (11kV or 33 kV) powerlines on private property? How deep does the trench have to be? How expensive is the cable per meter roughly? Thanks Dave

[gregmcc]

no problem undergrounding 11kv or 33kv, but that is something your average electrician has never done - this is where your network company (or a contractor that works for them) should be involved. As far as cost, not a clue. Mostly this kind of thing is quoted per meter fully installed with different prices for Overhead or underground, quite often the network company will want the consumer to pay the full cost of install and then the network takes ownership and upkeep and an easement to access the installed gear.

Not to put a too fine a point on it, the consumer pays for it all, then network takes ownership, And you can't go anywhere else.......