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?

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.

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!

Our run is pretty long about 250-300m, big cable, single phase and an underground junction to reduce size before house. Meter is inside house. We then take a supply from the house to the garage another 150m.

We are at the end of the line and voltage sits at about 243-7 volts generally and during export can hit 253 volt.

3 hours ago, JpManning said:

50m run

Shouldn't really be an issue.

37 minutes ago, JohnMo said:

Our run is pretty long about 250-300m, big cable, single phase and an underground junction to reduce size before house. Meter is inside house. We then take a supply from the house to the garage another 150m.

We are at the end of the line and voltage sits at about 243-7 volts generally and during export can hit 253 volt.

Shouldn't really be an issue.

Thanks John, that's a really useful real world comparison. 250 to 300m on single phase with the voltage still sitting around 243 to 247V shows what a properly sized cable and a junction part way along can do. Worth the OP bearing the export side in mind too: if solar is planned, a long run can push the voltage up towards 253V and inverters can trip on overvoltage, so it's worth telling SP Energy about any planned PV or battery when they quote, so the cable is sized for export as well as import.

For clarity on export, if grid power is low (typical of an Axle Export event) I can export at 5kW and grid Volts may only go up to 250V. Most other times, same export can be at it cause to 253V

Is there any downside to having the meter in a detached garage? I seem to remember a few on here over the years have had meters away from the house. I have an existing garage we hope to keep and would be handy to get meter connected there and can get site power then

20 minutes ago, Oz07 said:

Is there any downside to having the meter in a detached garage? I seem to remember a few on here over the years have had meters away from the house. I have an existing garage we hope to keep and would be handy to get meter connected there and can get site power then

You might want to install something that needs to monitor import / export current for instance, such as a PV diverter. This would require a current clamp on the incoming cable. So if you opt for a remote incoming supply, install a separate duct between the garage and the house through which you could pull any required cable for this purpose.

2 hours ago, ProDave said:

You might want to install something that needs to monitor import / export current for instance, such as a PV diverter. This would require a current clamp on the incoming cable. So if you opt for a remote incoming supply, install a separate duct between the garage and the house through which you could pull any required cable for this purpose.

I think i would want a pv diverter to tell pv to charge up the water tank. How big of a cable and duct is this going to require? Am I setting myself up for problems? I am also considering extending the garage so it adjoins the house. I suppose no duct needed then can just take the cable thru

If you plan for 2 cat5 cables that should be enough for almost anything you plan. But if you are putting in ducting then the cost of the ducting is miniscule compared to digging the trench so I would always put something bigger in just in case. 50mm ducting is pretty standard IIRC. If running on a surface then normal 25mm conduit should be ok. Worst happens it's easy to add another, but digging a trench, do it once and hope you never touch it again.