dual immersion heater

[JD Hogg]

I got a job next week to connect up a hot water cylinder which has dual 3kW immersion heaters. Ideally I would run 2 new 2.5mm circuits from 2 16A MCBs on separate RCDs but there are not enough spare ways in the CU. Is there any reason why I shouldn't run a 4mm radial on a 32A MCB and split it at the tank into a timed and a boost immersion.

It's only about 7m of cable under a floor.

Cheers

 

[malcolmsanford]

Depending on costs I would run your 4/6mm to a little enclosure and fit a couple of 16amp MCBs, so if an element goes down you can isolate it and still use the unit while you get a replacement.

I would use a 32amp RCBO at the main CU as well

 

[Guitarist]

Remember, the MCB is protecting the cable, so as Malc says, 2 x 16 amp MCB's would then protect your new heat-res cables.

 

[bradder]

If this is for economy 7 then 1 circuit to the tank and use a E7 quartz controller (which will switch between the 2 elements)