Immersion heaters tripping

[terryplumb]

Your 40 amp circuit, feeding the off peak immersion is not protected by an RCD ,and one of the circuits marked storage heater is ( assuming that's incorrectly marked and it is supplying the other immersion), and the RCD trips when the off peak immersion is energised ,then its highly likely that the neutral from the off peak immersions circuit is in the wrong neutral bar in the consumer unit .

 

[crystal ball]

As above something must have changed maybe the sparky disconnected the neutrals to test and got them crossed over

 

[EFLImpudence]

the 40amp is fine for both immersion heaters as they are 2.4kW rated each.

Yes, it would, in fact, be good for three 3kW immersion heaters.

However, they can't both be from the same MCB, as you have already deduced.

 

[TNDU]

Your 40 amp circuit, feeding the off peak immersion is not protected by an RCD ,and one of the circuits marked storage heater is ( assuming that's incorrectly marked and it is supplying the other immersion), and the RCD trips when the off peak immersion is energised ,then its highly likely that the neutral from the off peak immersions circuit is in the wrong neutral bar in the consumer unit .

i think the green storage heating MCB is the day time immersion heater, which is protected by the RCD. the 40amp MCB is not protected by the RCD because it is labelled in red and only the green labelled MCB are protected by the RCD?

why would two of the MCB not have RCD protection?

 

[terryplumb]

i think the green storage heating MCB is the day time immersion heater, which is protected by the RCD. the 40amp MCB is not protected by the RCD because it is labelled in red and only the green labelled MCB are protected by the RCD?

Thats all correct.

It's not unusual for several circuits not to have RCD protection on older installations

 

[TNDU]

Thats all correct.

It's not unusual for several circuits not to have RCD protection on older installations

i thought the RCD protection is at the consumer unit? so why would the consumer unit be made without RCD protection for some of the fuses? sorry, i know a little bit about electrics but very little.

 

[crystal ball]

At one time it was thought to be bad practice to include lights on the RCD side