Amps

 

There is something you MUST take into consideration - it’s called Ohm’s Law. This formula allows you to work out watts, volts, and amps. If you have two, you can instantly see the third...

WATTS - VOLTS - AMPS

 

We know that your supply is 240 volts, so we already have one of the three. The next is the total wattage of all your heaters.

Let’s say it’s 12,000 watts (12 kW).

All we have to do is divide 12,000 by 240.

It equals 62.5...amps.

Why does this matter?

Because some smaller homes (especially) may only have a 60 amp fuse on the main board. This must be changed to a higher rated fuse for you to use your 12 kW heating system (and that’s before we’ve even taken into account your general electric use, like kettles, tumble dryers, etc.). Even if your home had a 100 amp fuse, you wouldn’t be able to install a heating system which totalled much over 20 kilowatts (and that’s only ten 2 kilowatt heaters!) because your amp draw would be 83 amps before your general electric use. It would pop! Many homes (from our experience) appear to have 80 amp fuses. So you wouldn’t want a heating system to be consuming much above 15 kW (on an 80 amp board fuse). On a really cold day, with your system going flat out, and you decide to cook dinner, you only have around 4 kilowatts left! So the first thing to do is add up your heating requirements (total wattage) and call your electrician in to see what fuse is fitted on your supply board.  Or you can switch to a three-phase supply.