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Longer electrical connections

Featured Replies

Just trying to understand my options and implications around a 'long' connection from the main supply in the road to the house.

Ideally, I want the meter inside the house in the technical room, and from the main supply in the road to that location will be around 50m. SP Energy have said that anything over 35m will require either 3-phase or a larger cable. I'm awaiting a quote on these, but is there any advantage of one over the other?

The second option is to have an external kiosk housing the meter which would be at the side of the house and about 30-35m from the supply in the road. Due to root protection constraints we don't have much choice on location of this kiosk. From the kiosk to the distribution board in the technical room is around another 20m.

We don't need a temporary site supply and we are quite tight on space at the side of the house where the kiosk would have to go so if I can get away without one I would do so. We had an external kiosk on our last build and I hated the fact it was there!

So, what are your thoughts/views and is there anything else have I not considered?

Worth asking SP Energy a few things before you pick. First, whether the 35m limit is measured along the actual cable route from their main to your cut out, because digging around root protection areas can add a lot to the real length. Second, what the quote difference is between a larger single phase cable and a three phase supply. Three phase only really earns its keep if you want big loads like multiple EV chargers, a large heat pump or an induction hob setup, otherwise a larger single phase cable is usually simpler and cheaper to run.

On the meter, the real issue with a 50m run is voltage drop and who owns what, so ask where their responsibility ends and yours begins. If the meter sits in a kiosk and you run 20m of tails or armoured cable to the board, you will need to size that cable for voltage drop and the maximum demand, and your electrician needs to calculate it properly. Duct everything now while the trench is open, and add a spare duct for comms. If the kiosk is the only way to avoid damaging roots, a low profile one can be clad or screened with planting, but check the DNO rules on access first.

I suspect for the longer run the DNO would size a larger cable, probably 95mm2 With an external joint to reduce to normal size to enter the meter box.

What are you going to use for a building supply if you don't have an external kiosk and don't want a temporary building supply. It sounds like you want to wait until at least the shell is up then get the supply installed?

  • Author
14 minutes ago, ProDave said:

I suspect for the longer run the DNO would size a larger cable, probably 95mm2 With an external joint to reduce to normal size to enter the meter box.

What are you going to use for a building supply if you don't have an external kiosk and don't want a temporary building supply. It sounds like you want to wait until at least the shell is up then get the supply installed?

We're doing a Danwood build and the house goes up in about a week. Groundworks guys have all said they don't need power so my ideal would be to get the slab in, then bring the power up through it with a temporary cabinet on the slab. Once the house goes up I'd get rid of the cabinet.

SP Energy are going to price the options up for me (well, I've asked them to!).

25 minutes ago, JpManning said:

Worth asking SP Energy a few things before you pick. First, whether the 35m limit is measured along the actual cable route from their main to your cut out, because digging around root protection areas can add a lot to the real length. Second, what the quote difference is between a larger single phase cable and a three phase supply. Three phase only really earns its keep if you want big loads like multiple EV chargers, a large heat pump or an induction hob setup, otherwise a larger single phase cable is usually simpler and cheaper to run.

On the meter, the real issue with a 50m run is voltage drop and who owns what, so ask where their responsibility ends and yours begins. If the meter sits in a kiosk and you run 20m of tails or armoured cable to the board, you will need to size that cable for voltage drop and the maximum demand, and your electrician needs to calculate it properly. Duct everything now while the trench is open, and add a spare duct for comms. If the kiosk is the only way to avoid damaging roots, a low profile one can be clad or screened with planting, but check the DNO rules on access first.

The RPAs plus driveway dictates the trench routes so the distances I quoted are the actual trench distances involved. Without the RPAs it would be a lot simpler!

I would imagine that my responsibility starts after the meter but it's a fair shout that the cable from meter to the house would still likely have to be larger than normal. Thinking about it, this would mean I better put a decent sized duct in.

What comms are you thinking of? Not a thing I'd considered so I'm assuming I've missed something

Just get the larger supply cable run directly into the house, we have our meter 100m from the house and it has meant a lot of extra switch gear and different Earth configuration to make it all work.

If I had to do this again I would move the meter up to the house.

  • Author
4 minutes ago, Russell griffiths said:

Just get the larger supply cable run directly into the house, we have our meter 100m from the house and it has meant a lot of extra switch gear and different Earth configuration to make it all work.

If I had to do this again I would move the meter up to the house.

Thanks - exactly the sort of intel I was looking for? Will wait with bated breath for the quote!

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