The standard supply for a new house seems to be circa 18KVA single-phase. I have a client who needs to make application for a supply for a new build house at 400m2 with the only certain information being that an air source heat pump is to be used for heating. The client simply does not know what the electrical loading might be. The house is only coming out of the foundations but the DNO supply may take many months as the house is in a relatively remote rural location, thus loading details are required before the DNO will consider progressing the proposal. It is a big house, but that is what it is, just a big house. I am inclined to advise a standard supply but 3-phase as with a large AS heat pump, maybe shower, cooking and perhaps an EV or two, 18KVA wouldn't be long being gobbled up. As we move towards a higher reliance on electric as a power source for some heavy current-using equipment, it might be that 18KVA is no longer a realistic standard supply for even the smaller property.
Two EV chargers each of 22 Kw may sound excessive, but if that is what the client wants, then the electrical installation must be able to supply that load, and the heat pump, and a reasonable loading for other appliances.
Since the EV chargers and the heating will consume about 70 amps per phase, provision of a three phase 100 amp supply looks a bit marginal.
After the EV charging and heating is considered, we are in effect left with a three phase 30 amp supply for everything else which sounds inadequate, unless some form of load limiting is used.
A house of this size may imply either a large family, perhaps with more than two electric cars, and the demand for multiple showers, or alternatively might suggest live in staff.
Even if electric showers are avoided, multiple showers from stored hot water is a significant demand. I doubt that a single 3kw water heater would cope with that load.
A large household might well have multiple washing machines and tumble dryers.
I consider it probable that an off peak tariff would be used for EV charging and water heating. One supplier at present have an attractive sounding tariff that offers a heavily discounted rate for 5 hours overnight.
Adoption of this or a similar tariff might suggest a MINIMUM loading of 80 to 85 amps per phase during such hours.
Two EV chargers each of 22 Kw may sound excessive, but if that is what the client wants, then the electrical installation must be able to supply that load, and the heat pump, and a reasonable loading for other appliances.
Since the EV chargers and the heating will consume about 70 amps per phase, provision of a three phase 100 amp supply looks a bit marginal.
After the EV charging and heating is considered, we are in effect left with a three phase 30 amp supply for everything else which sounds inadequate, unless some form of load limiting is used.
A house of this size may imply either a large family, perhaps with more than two electric cars, and the demand for multiple showers, or alternatively might suggest live in staff.
Even if electric showers are avoided, multiple showers from stored hot water is a significant demand. I doubt that a single 3kw water heater would cope with that load.
A large household might well have multiple washing machines and tumble dryers.
I consider it probable that an off peak tariff would be used for EV charging and water heating. One supplier at present have an attractive sounding tariff that offers a heavily discounted rate for 5 hours overnight.
Adoption of this or a similar tariff might suggest a MINIMUM loading of 80 to 85 amps per phase during such hours.
