Immersion tripping rcd.

[harrymonkfish]

Hi folks.

Changed a Cu today. No rcd protection, Changed for a split way board. All tests were fine. Came to do Zs test on immersion heater - everything fine. Turned on DP switch to immersion and rcd tripped.

Had a good look at all cables for the circuit and all seemed fine. Disconnected immersion from switch, turned on switch and everything ok. No trip.

Is this a common problem with immersion heaters? It is quite old. Is this a case of just put in new element?

Many thanks
Harry

 

[Des 56]

Does the immersion need to be on the RCD ?

They do tend to have lower resistance to earth because of the element
If the element tested ok for insualation resistance,perhaps it may be adding extra leakage to circuits already leaking which are on the same rcd and is then enough to tip it over the limit
It wasn't usual to have them on RCDs but it still should be healthy enough to do so
If its suitable remove the RCd protection

 

[harrymonkfish]

Thanks des.

I do have the option to place the immersion heater on an unprotected way. That would be ok then?

Sounds like the perfect solution to me.

cheers
harry.

 

[pushrod]

Would it not depend on the route that the cable takes to the immersion heater? Would have to be surface mounted or below 50 mm.

 

[harrymonkfish]

Would it not depend on the route that the cable takes to the immersion heater? Would have to be surface mounted or below 50 mm.

The cable is surface run in the cupboard and then taken through the floor joists to cu.

 

[kung]

Agree with Des there ! also rcbo's or if dual rcd board if element pans out ok try turning everything off then try just the immersion circuit and add circuits or try swopping to RCD 2. Also does the RCD pass the half current test ?

discon element and run a RCD ext lead from a socket then put a plug on immersion and plug and play ! if trips RCD change element !