i need to install an in line electric water heater
i have a choice of 7kw or 8 - 9.6kw
whichever i choose i may overload my trip switch
is there any way to reduce the current.
obviously this will reduce the heating effect but that is not a problem.
the problem is I may need to keep the current below the level of my trip
With that load you need a dedicated circuit from your consumer unit/
distribution board. The 7kW needs just under 30A, and 4mm cable unless
it's a "long" run (say over 15m) or runs buried in thermal insulation -
then you'll need 6mmsq minimum; the 9.6kw will pull 40A and would be
better wired in 10mmsq (bit of a bummer to work with). No sensible easy way
to reduce this load: water needs a lot of energy to heat it! If you
don't need much temperature rise, try to find a 3kW inline heater instead.
HTH - Stefek
The only way to keep the current below the level of your trip is to work out
the kW equivalent of your trip current and keep below that. For example, if
your trip is 20 amps, watts = volts x amps = 20 x 240 = 4800 watts or 4.8 kW
There's no magic way of preventing a 9.6 kW heater from drawing 40 amps!
I suppose you could limit the power by reducing the voltage with a variac -
but that would be expensive and would only have the same effect as using a
lower power heater.
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