How do you wire a 240V heater that has green black and white wire and the terminals are brown 'load' blue 'neutral' and black 'ground'?

Answer 1

1. If the heater itself has Green, Black and White wires coming out of it, those wires are likely to be: Green for Ground, Black for Hot and White for Neutral. (As in the wiring codes for the US or Canada or countries which use similar wiring codes.)

2. When the question goes on to say "Terminals are Brown, Blue and Black", that seems to be in conflict with the information stated above in Line 1. Exactly which terminals are you describing? Are they on a plug on the cable already coming out of the heater? If it is a US-style plug then it might be for use on a 240 Volts outlet, in which case the pins on the plug would possibly have a Brown terminal for the Red "hot" , a Black Terminal for the Black "hot" and a Blue terminal for the Neutral?

3. Alternatively, maybe the questioner is in the UK, and the terminals being described are actually inside a UK-style standard 3-pin power plug, which could have a Brown terminal for Load, a Blue terminal for Neutral and (possibly) a Black Terminal for Earth (= Ground).

4. If the terminals being described in the question are not inside a plug, where exactly are they? Are they in a wall box intended for a hard-wired connection to a water heater?

5. If this is actually an appliance designed for use on 60 Hz supplies such as in in the US or Canada, which it sounds as though it may be from the colors of the wires given in Line 2 above, then you need to check very carefully if it was designed to be used on a US-style 120 Volts outlet, not 240 Volts. THERE SHOULD BE A RATING PLATE ON THE HEATER WHICH TELLS YOU THE VOLTAGE IT WAS DESIGNED TO USE. IT SHOULD ALSO STATE THE POWER TAKEN BY THE APPLIANCE. For domestic or office use it will probably be 3 KiloWatts or less.

6. If the rating plate says the heater was intended for use on a US-style 120 Volt supply, do not try to use it on a 240 Volts supply! (If you do, a fuse will blow and/or a breaker will trip!)

7. If the rating plate says the heater was intended for use on a US-style 240 Volt supply, then, if it is to be used on a UK 240 Volts supply using a UK standard power plug, wire it like this: Black wire to the Brown Terminal in the plug (labelled as Load or Live), White wire to the Blue terminal in the plug (labelled as Neutral), Green wire to the Earth terminal in the plug.

Black goes to brown, white goes to blue, and of course green would be your ground.

Always be sure to switch off the main power switch and breakers at the main panel before you attempt to do any work on any mains power circuit.