This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Correct wiring for twin 3Kw Immersion heaters

Morning folks,

I have a simple question presumably for an electrician that I could do with the answer to having just witnessed some poor installation practise. As a plumber I recently changed a 3.0Kw immersion for a 3.6Kw immersion. It was then left for the electrician to wire in whilst doing other work in the house. He used a 1.0mm conductor with that size immersion. 16amp Mcb on the consumer unit and the wire got a little warm, melted the insulation and caught fire. Very luckily the customer was in the room at the time and caught it in time to go and isolate the power and put out the smoldering wire.

Now this fella is going to go and wire in dual immersions both 3Kw to a single economy 10 unit. How should this be done safely? I'm presuming a single cable radial from the consumer unit 32amp MCB with either a 4mm or 6mm cable so 37amp or 47amp clipped direct with a junction box with two separate again 4 or 6mm cables and not anything less from the junction box? I'm asking since this is work that is taking place on an Island off the west coast of Scotland where building control or any CPS is totally absent. 

Thanks

Parents
  • It could be possible to use 1.5 mm for the circuit, but I would not use it for a new installation,  but it might be found on an existing installation. 

Reply
  • It could be possible to use 1.5 mm for the circuit, but I would not use it for a new installation,  but it might be found on an existing installation. 

Children
  • When I first started out in the industry I once used 1.5mm2 T&E cable to supply a new immersion heater in a house. I was trying to save money. A section of the cable that was clipped direct onto a brick wall ran warm. I would not now use 1.5mm2 cable for a 3kW immersion heater. It will overheat the cable and cause energy loss in the form of cable heat.

    Z.