My Shower is causing my RCCB to trip...please help!

[thedude1]

Hello good people I am new to this forum and need some help.

Last night the wife pulled the shower ceiling cord switch and all the sockets in the house went out.

I have a mira zest 8.5 electric shower in my home. When I pull the ceiling switch cord to turn it on the RCCB in my split level consumer unit trips off affecting all the MCB's on that side. There are 2x socket MCB's and the shower MCB on the RCCB side of my consumer unit.

My main lights, cooker etc are all on the other side from the RCCB and work fine.

The shower switch pullcord lights up for a while then switches off, sometimes it switches off straight away sometimes only when I turn the shower dial on the shower unit. On the actual consumer unit it is only the RCCB switch that trips 'off' the actual shower and sockets MCB's do not trip and stay 'on'. I can still get cold water through the shower regardless of whether the shower cord is pulled or not.

What is the problem here? Is it the RCCB? Is it the shower ceiling switch or is the heating element in the shower itself? or something more sinister?

How do I fix this?

Thank you gents

 

[wingcoax]

If you are not FULLY confident in your abilities then you need to get a sparks in. It does sound like a fault, either in the shower or the switch. If you feel confident, then check all connections and if you have a multimeter then check continuity and for leakage between conductors(which is usually the cause of rcd trip) If ok in switch then probably the heater element in the shower.

 

[thedude1]

Hey friend
Thanks for the rapid reply much appreciated. I am glad you have said you think its either the ceiling switch or the shower itself. That is what I have suspected and getting a second opinion is reassuring.

Im a novice and don't have the knowhow or gear to go testing the consumer unit but I have lived here for 4 years and it is a modern flat. All wiring looks neat, all MCB's labelled and modern. like you I think it is the ceiling switch or the shower at fault.

Can the RCCB (I take it thats the same as RCD?) actually break just like a fuse then? Like I say the 2x sockets and 1x shower MCB on the RCD side still stay 'on'.

Lets say we assume it is either the ceiling switch or the shower. What would you do to sort it? Would you go and buy a new switch first and if that doest work a new shower?
Thanks again

 

[thedude1]

Sorry for being such a dunce but do I need a double pole switch? 45 or 50 amp?

When I look at the switch wiring it has two sets of black, two of red and two of earth. Does this mean it's double pole? Does it matter if its 40 or 50 amp and is bigger better?

Thanks again

 

[Gavin77]

Before going out to buy another switch, why dont you disconnect the shower wiring from the switch? (With the power off of course)

Then if the switch doesnt trip the RCD, then you know its the shower at fault.

As for the switch, yes you need double pole. Size. Use the formula of Power = Volts * Amps to work out the minimum current switch you need. But yes in general, bigger is fine.

 

[thedude1]

Gavin77

Your a star.... as I say i'm a novice when it comes to electrics, but your simple solution is exactly what ive been looking for. One of those ones when you see the solution that I say to myself...why didnt I think of that!?

I followed your advise & low and behold.....it's the switch that's at fault. When I disconnected the shower wiring from the switch and pulled the switch the RCD tripped.

So I take it that means it can only be the switch??

I will go and get a switch tomorrow and let you know the result! Cheers for the switch info too! Champion.

 

[riveralt]

I will go and get a switch tomorrow and let you know the result! Cheers for the switch info too! Champion.

It is also possible that your cable at the switch came loose and this caused it to heat up and burn either/both the switch and cable.
When installing the new switch you need to strip any damaged cable back to clean copper and ensure that the terminal connections are tight.

 

[thedude1]

riveralt

Cheers for that additional piece of assistance dude.

I checked that out too but no obvious burning although it looked a bit shabby, I have have taken the switch off, dismantled it and cleaned all the copper contacts etc then put it back together and re-installed it then powered up again to see if just needed a clean. But the same problem when I pull the bugger.....need a new switch. No cable shroud fouling the contact. Must be the switch just giving up the ghost. I had a look at it and it passed it's quality control check in 2001 so I suppose 13 odd years from a switch is as good as it gets?

Cheers

 

[thedude1]

Foiled again gents!

New switch fitted in today from screwfix. Pulled cable and same again!? I think this means it must be the shower???

At least I have a new switch and have eliminated that possible culprit!

Do I need a whole new shower or just a heating element? I looked inside the shower gubbins an nothing obviously wrong. I had a shower go before in another house and it was the heating element. I guess this time around it is a heating element again, not really much else to go wrong inside a shower is there?

Can anyone say what the problem could possibly be back at the RCD side of things if infact the shower isnt faulty?

Thanks again

 

[Dave2010]

hey,

you could check the resistance of the element if you can get into the shower and onto the terminals with a meter (power off obviously)

a decent 8.5kW element should give around 6.22/6.77ohms if im not mistaken depending on your voltage

might narrow it down a bit for you

 

[thedude1]

Dave2010

Ok I get the picture here. Im gonna have to go out and get me a multimeter and learn how to use it. Seems one of these gizmos is essential when dealing with electrics else im just guessing in the dark.

I can get easy easy access into the shower terminals on the heating element no probs. Thanks for the technical info on ohms readings etc

I suppose I should have got one of these multimeters and learned how to use it by now anyway. I can get a heating element for £57 and am inclined towards buying as it looks simple enough to connect it, but I suppose in the long run I would be better off with a mutimeter so I am not throwing good money after bad.

Will keep you posted

Cheers

 

[Dave2010]

hey,

Yes get yourself a multimeter but dont get the cheapy things from wilko's or asda etc try get the best you can afford from somewhere reputable. And in the future it will always be handy to have

hmm at £57 for an element you could be looking at a whole new shower nearly for that price and a nice new warranty to. Ensure you search the net for the best price on your element

 

[canduit]

dude. You said earlier you disconnected the shower side of the switch but it still caused tripping?

 

[thedude1]

canduit

Yeah man its peculiar. Here is the series of events.

1. The wife pulls the cord and all the sockets go out and the RDC goes down the instant she pulls the cord (without touching the dials on the shower)
2. In the morning I try it again and when I pull the shower switch the RDC stays up and the sockets work (only when I turned the dial on the shower did the RDC and sockets go down)
3. I reset the RDC (it will only reset to 'up' when the shower cord is pulled to 'off' if the shower cord is pulled 'on' the RDC wont stay 'up') and I try again this time it all goes the instant I pull the shower cord.
4. I disconnect the shower from the shower switch and try again. The RDC and sockets go without the shower being wired to the switch. So i assume switch is faulty.
5. I get new switch and fit it. I pull shower cord and RDC stays up and sockets dont go.....hooray I think it is fixed, so I turn the shower dial and bang the RDC goes up and sockots go out?
6. I try again and RDC goes up and sockets out instantly on pulling the cord. So Now I dont know whats wrong but think it must be the shower??

In a nurshell, sometimes when I pull the shower cord everything is fine
until I turn the dial on the shower and sometimes when I pull the shower cord it all goes instantly!

I have to admit its pretty confusing. The problem seems to be variable.

DAVE2010
Thanks for the info, much appreciated

 

[canduit]

It could be the cable from your consumer unit (fusebox) to the switch, but without specific and costly testing equipment its hard to say. Did you say the cable "looked a bit shabby" or was it the old switch? You may have to get a sparky to have a look at this circuit.