There seems to be a standard installation developing for domestic EV charge points where it is 6mm2 no matter what. I checked one installation which will have around 9v dropped on a 7Kw charger. Ok, I acknowledge that the full load current won’t be pulled at all times but it can be assumed that there will be long periods when it will. Multiply that by an ever increasing demand across the nation and we can expect to see considerable energy wastage. Perhaps, we should be setting tighter limits than 5%.
I based the calculations around 10m of T&E with a 7kW EV charger as a load for 8 hours a day with a full charge for 200 days of the year at 15p per kWh.
A 6mm cable for a constant 7kW load has a cable energy loss of 60.4W running at 46.5 degrees C. So 7.25p per day x 200 days = £14.50
A 10mm cable for the same load and duration has a cable energy loss of 34.6W running at 38.7 degrees C. So 4.15p per day x 200 days = £8.30
The difference in cost for running the cables per year = £6.20
T&E from TLC costs for 10m of 6mm £25 and 10mm £39 difference = £14 plus VAT. = £16.80
So to recover the cost of uprating he cable from 6mm to 10mm it would ,take 2 years 8 1/2 months assuming no interest on the capital outlay.
Please feel free to check my calculations as I was never any good at maffs?
I based the calculations around 10m of T&E with a 7kW EV charger as a load for 8 hours a day with a full charge for 200 days of the year at 15p per kWh.
A 6mm cable for a constant 7kW load has a cable energy loss of 60.4W running at 46.5 degrees C. So 7.25p per day x 200 days = £14.50
A 10mm cable for the same load and duration has a cable energy loss of 34.6W running at 38.7 degrees C. So 4.15p per day x 200 days = £8.30
The difference in cost for running the cables per year = £6.20
T&E from TLC costs for 10m of 6mm £25 and 10mm £39 difference = £14 plus VAT. = £16.80
So to recover the cost of uprating he cable from 6mm to 10mm it would ,take 2 years 8 1/2 months assuming no interest on the capital outlay.
Please feel free to check my calculations as I was never any good at maffs?
