RCD trips when Shower is turned on, shower is powered by seperate RCBO

alphonse mephisto

Just had a quick look at a job for the morning there.

RCD trips when RCBO shower is turned on.

RCBO and shower continue to run.

C/U wiring looks fine.

The shower is old.

Any thoughts or suggestions?

Also, I turned the power off and quickly belled everything out. The only problem i came across was the downstairs socket circuit bells out between L-N-E but works completely fine. Strange.

Related?

Obviously ill do alot more tomorow, was only able to get in for 15 minutes today.

Anyway, its always nice to be able to put it to people with more experience than myself.

Thanks as always lads!

ptogher14

If you only had the power switched off when you belled out the N-E should have belled out. L-N is possible if appliances were plugged in.

Did the RCD problem arise out of the blue?

Bruthal

Possibly a Neutral Earth fault on another circuit controlled by the RCD. High loading from shower causes enough of a diversion from the main neutral bar to this earth fault, tripping the RCD. Any outside of house circuits from this RCD, with possible water ingress?

Since the immersion, if there is one, has a DP switch, it is easy to eliminate from the equation, try switching that of first and see if the shower avoids tripping the RCD.

Bruthal

ptogher14 wrote: »

L-N is possible if appliances were plugged in.

Indeed it is, particularly when using sensitive electronic continuity testers which show continuity on items which are quite a few ohms.

alphonse mephisto

Yeah I was using a fluke tester and my one bells for N-E anyway, TNCS and all that.

He said hes had the problem since he got the board done about ten years ago but only bothered enough by it now to do something.

There is a outside circuit and I would imagine its taken from a down stairs socket so I will look into water ingress in that.
Although the outside circuit is only recent but he is saying hes had the problem years now.

Im leaning toward some current leakage, possibly N-E fault and a switching surge from shower messing with the RCD But as always im open to your thoughts and opinions so keep them coming!

Thanks for the input!

tomdempsey200

i'd be checking earth faults downstream on the rcd anyhow

and maybe even swop out the rcd(see what happens)

tomdempsey200

it trips immediately when you switch on shower

every time
?

ptogher14

I'd second bruthal with the immersion

alphonse mephisto

Trips everytime when the shower is turned on.

He also said it will trip from time to time for no apparent reason.

alphonse mephisto

And yes, sorry, Immediately

kelledy

this exact problem was in a house i lived in before. when the panel was changed the immersion switch had to be off for the shower to run or aomthing along them lines. cant fully remember but it 100% involved immersion switch

Bruthal

alphonse mephisto wrote: »

Yeah I was using a fluke tester and my one bells for N-E anyway, TNCS and all that.

If you switch off the rcd, you can now check for N to E faults on its circuits with the tester. All circuits will be tested in a single go. To find an individual one if a problem shows, all neutrals need to be disconnected from RCD neutral bar and tested to earth bar.

As said, immersion can be first eliminated by simply switching it off, although if this is happening years, its likely something that's not used much, as a circuit with neutral to earth fault will itself trip the RCD when its used, and would be noticed besides the shower causing it.

cast_iron

Definitely sure the RCBO live isn't wired from the RCD live?
If not, then isolate the neutrals as Robbie describes to identify the problem circuit.
I'd then look into it being a faulty RCD as Mceebee says.

alphonse mephisto

I had to fix a few things, polarity was wrong on circuit going outside, have to laugh.

IT WAS THE IMMERSION.

Neutral and earth were reversed and had been since the house was first wired. Problem only started to show after he had the new board with MCB's and RCBO and "ELCB" put in.

The Immersion wouldnt have been the first thing id have checked as its wired off the downstairs sockets so my hats off to you lads, great help as always!

Thanks very much!!