Immersion heater tripping mcb when timer switches off

[Paddy-08]

Hi. I’m new to this but was woundering if anyone has had this problem. My immersion heater keep tripping the mcb when the timer switches it off. The mcb won’t reset unless the timer is set to on which works fine but as soon as the timer is up it trips the mcb again. The timer I have is a Horstmann Economy 7 quartz. Thanks for ur help

 

[Wilko]

Hi Paddy and Welcome to the Forum.
Sorry to hear you've got an electrical problem, but hopefully someone will be able to help
Can you have a close look at the switch that trips and report back what it is? e.g. it may have B16 written on it? Or is it the RCD (one with a test button) that trips?

 

[Paddy-08]

Hi how are you? And I hope so it’s doing my head in it’s the main RCD with the test button on. It’s worked fine and then just tripped in the night

 

[Allan Hogg]

My first thought on reading the problem is that there is a slight delay in the opening of both poles of the double pole switch timer. This could trip an RCD.

 

[Lagentium]

Paddy are you an electrician? If so I'd connect it straight through and take the timer out of the equation and turn it on and off via the local spur and see if it trips. If you aren't qualified then get someone who is to have a look and they may do the same mate.

 

[buzzlightyear]

element problem probably how old is the hot water cylinder.

 

[Paddy-08]

Yes that would make sense and I think it’s must be the timer. But if the timer is set to off I can’t reset the RCD

 

[buzzlightyear]

get a plumber in and ask him to test it for you .the reason the element if it needs changing by a plumber .not a sparky because of the head .

 

[Dave OCD]

Buzz I don't think your average plumber would have a clue about electrically testing an immersion element.

 

[buzzlightyear]

Buzz I don't think your average plumber would have a clue about electrically testing an immersion element.

possible one with electrical knowledge.

 

[Dave OCD]

Yes possibly - and test equipment. I'd say electrician to test, plumber to change element if necessary.

 

[shaun1]

If it is not possible to reset the RCD at all with the timer in the off position, then this sounds like a fault with the timer (or a relay it controls). Perhaps the NC contact is connected earth or similar.