Just a quickie. Just reading the instructions for a new 6kW water heater and it says to calculate cable section as 5A/mm2 for runs under 20m. The existing cable is 4mm2 but by this reckoning it's too lightweight. I thought 4mm2 cable was 30A?
Am I wrong, and therefore need to replace the existng cable with 6mm2, or is 4mm2 fine for a 6kW load?
In article , Danny Monaghan writes
I agree with you, as does the TLC calculator (for all routings except "buried in a thermal wall").
Cable resistance over 20mtrs on 4 mm csa' is not good, as the instruction book says, but actually, if the cable run you're making is on or over 15mtrs in length, then you will need a heavier gauge cable to reduce losses? If it is over 15mtrs, then you will need to make the cable run in 6 or 10 mm csa' cable for the load you have on the water heater. You will get away with 4 mm csa' up to 15mtrs for a 6kW load, but only to that length.
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