How do I calculate my building's required electrical supply capacity?

emv

Our building (commercial, includes our home) currently has a maximum load electricity meter which formerly was the meter for a whole village & so is massively over capacity. At some point this will lead to a very high capacity charge (something like £94.00 a month!) and we'll move onto half-hourly meter readings. Our distributor has suggested that we estimate the capacity that we need & ask them to quote for an appropriate size meter.

We have a smart meter & this shows that our max usage since the meter was installed a couple of weeks ago is 8.6KVA. They mentioned a meter with a 45KVA capacity which would obviously be more than adequate but if we'd also be paying a capacity charge per KVA then this would cost us about £42/month + standing charge.

Our need for electricity will increase in future, we'll eventually have a biomass boiler (and the distribution company have said we need to factor in the power required for the hopper) and we will use more by way of lighting, computers etc. But how do I calculate what supply capacity we will need? happy to do the legwork if it's a case of counting up likely usage in W/KW & converting this to KVA, I'm just not sure if this is the right approach?

Em

ChumpusRex

You've got the right idea.

You need to add up the kVA requirements of all your equipment that you might conceivably use, leaving some room for further expansion in case situations change.

So add up lights, computers, heating/hot water, air conditioning, lifts, etc. Add a safety (do you need capacity for emergency electric radiators in case of boiler breakdown) and growth margin and see what you get.

By the sounds of things, you are unlikely to exceed the capacity of a 45 kVA supply. There are more complex calculations which take into account "diversity"; the fact that not all equipment will be used together (e.g. You won't be using emergency heating at the same time as air con), but if your initial calculations are way under the smaller supply capacity, then there's not much point in doing more difficult calculations to get a more accurate lower value.

If you don't feel comfortable doing this, then an electrician would be able to do the estimates and calculations for you, but would need a detailed breakdown of all your intended electrical equipment.