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RCD protection for existing heater circuits


Customer wants existing storage heater circuits moved over to on-peak. He is having some fancy eco heaters that i am not fitting installed by another party and they, as far he knows, only require an on-peak supply.  The existing fuse box does not have rcd protection. If i change it over will it need RCD protection.( i don't think it does as i am not changing any circuit wiring) i appreciate it would be a C3 on a report as it is because of cable depths.  The cables obviously are already in place with 20amp switches on.




  • If you're just moving the tails from one Henley block to another, I'd say it's OK to leave the final circuits without RCD protection. Certainly point out the issue to the customer and suggest that this would be a good opportunity for an upgrade, some plain words in the 'comments on the existing installation' box if they don't fancy adding an RCD.

    If moving the final circuit wiring from an MCB/fuse in one CU to another ... I'm less comfortable, but I think would reach the same conclusion as still none of your new work itself requires RCD protection (presuming the CU isn't in a bathroom or anything odd like that).

        - Andy.

  • Would this be the sort of eco heaters that use the same amount of electricy as normal heaters, produce the same amount of heat, but cost ten times as much and come from Germany?

  • I don't know. I have nothing to do with that side of it. Slight smile

  • Thanks Andy.  Thinking about it i will ask the customer to ask the installers if the manufacturers instructions require one as well as i don't know what is being fitted.


  • That sounds about right. The general uneducated are conned left, right, and centre by extravagant outrageuos product claims. Many of my customers are removing off peak cheap rate storage heaters because they say that they are expensive to run. They are installing on peak heaters of the type described here.


  • I was going to suggest poor teaching, but I think that it just reflects low interest in "STEM" subjects. OK, I was never a good musician (but enjoyed singing) and cannot draw for toffee; so each to his own, but at least I learned the basic laws of physics.

  • Would this be the sort of eco heaters that use the same amount of electricy as normal heaters, produce the same amount of heat

    Probably not.  Traditional storage heaters while 100% efficient of themselves do have significant inefficiencies when it comes to their basic job of keeping the house warm. Old ones would take pretty much the same amount of energy to charge up overnight regardless of how much heat was actually needed to keep the house warm the following day (depending on the weather) (OK there might have been some manual adjustment  .. which nobody used day-to-day), they kept on kicking out heat even if people felt too warm and opened a window and so on.  The "LOT 20" versions use a number of tricks to significantly reduce the energy consumption while still keeping the place comfortable. Most off-peak systems charge off-peak rate for the 24hr circuits during off peak times, so as long as the timing is right, the benefits of off-peak should be kept, while still having power for control (and possibly a boost) during the day without the need to run a duplicate cable to every heater.

       - Andy.