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2 electricity supplies to one building

Former Community Member
Former Community Member
Hello, I am a not an engineer but need some advice on uk wiring regulations please. 

A national utility company is fitting a 32A charger in my garage for an electric vehicle. 

The garage is detached from my house but there is an existing circuit from the house consumer unit to the garage for lighting and a power socket. The cable runs along a garden wall. 

The new charger will have its own cable run from the same consumer unit in the house down to the garage. 

My problem is that the engineer who came to do the installation refused to do it as he said the garage is a building in its own right and regulations do not allow 2 supplies to one building.

My question is: Do 2 wiring circuits from the same consumer unit constitute 2 supplies If the consumer unit is located in an adjacent building? 

I would have thought that this was still a single supply and to have 2 supplies you need 2 separate meters with 2 consumer units which is not the case here but then, as I said, I’m no engineer. 

Edit.....The engineer stated that the regulation related to avoiding the risk of a voltage between 2 different earths. To me this again only makes sense if you were talking about 2 totally different supplies from different meters and therefore possibly different sub stations etc.
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  • 0
    I think that is being unfair.

    Here are the numbers. 40 million cars 10 million trucks and vans. so 50 million, the trucks and vans need an extra charge factor of 5 on average, which I feel is fair, so 90 million charge units.

    Cost 3 trillion pounds, some for heat pumps so let's say 2.7 trillion.

    90 million * £30 million = 2.7 trillion. That looks awfully accurate to me.

    How long do you think road tax and fuel duty for electric will stay at zero? In a big truck, they amount to around 80p per mile, so the same for electric lorries, with the price of electricity as it saves (no costs) around 20 pence a mile more than diesel. What you are failing to appreciate is that diesel is a very cheap and energy-dense fuel, and the retail price of electricity is very high compared to other forms of energy. I am also waiting to see the truck battery being charged at 2 MW for an hour rest (not needed with 2 drivers remember) because that is the energy that could be used in the next 4-5 hours. If battery charging is 90% efficient, that battery loses 200kW as heat, during charge, now that could be interesting as it would need to be spread throughout the load space unless there was a lot of forced air cooling equipment as well. This truck certainly has zero load capacity. Tesla hasn't had much luck with heavy trucks, lots of PR though. Services with 50 truck chargers might take 100MW, now that is quite impressive, more new EHV lines then and big transformers. Do you really think these are free? In the US, cross-state trucking is very common, and the rules are less prescriptive. Fuel is even cheaper than electricity. The case to do so is very poor.
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  • 0
    I think that is being unfair.

    Here are the numbers. 40 million cars 10 million trucks and vans. so 50 million, the trucks and vans need an extra charge factor of 5 on average, which I feel is fair, so 90 million charge units.

    Cost 3 trillion pounds, some for heat pumps so let's say 2.7 trillion.

    90 million * £30 million = 2.7 trillion. That looks awfully accurate to me.

    How long do you think road tax and fuel duty for electric will stay at zero? In a big truck, they amount to around 80p per mile, so the same for electric lorries, with the price of electricity as it saves (no costs) around 20 pence a mile more than diesel. What you are failing to appreciate is that diesel is a very cheap and energy-dense fuel, and the retail price of electricity is very high compared to other forms of energy. I am also waiting to see the truck battery being charged at 2 MW for an hour rest (not needed with 2 drivers remember) because that is the energy that could be used in the next 4-5 hours. If battery charging is 90% efficient, that battery loses 200kW as heat, during charge, now that could be interesting as it would need to be spread throughout the load space unless there was a lot of forced air cooling equipment as well. This truck certainly has zero load capacity. Tesla hasn't had much luck with heavy trucks, lots of PR though. Services with 50 truck chargers might take 100MW, now that is quite impressive, more new EHV lines then and big transformers. Do you really think these are free? In the US, cross-state trucking is very common, and the rules are less prescriptive. Fuel is even cheaper than electricity. The case to do so is very poor.
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