wtf

[glasgospark]

6 months ago we installed dual rcd db and rewired shower circuit .
Customer contacted me to say shower is tripping rcd, Triton changed element still doing same so I go up , shower works fine on medium at temp 10 but trips rcd when put to high , when it trips its tripping the other rcd and shower stays on .
so rcd that trips doesn't have shower circuit on it but when shower turned on to high shower stays on but trips rcd doing rest of house , bear in mind we done the work half a year ago , all circuits are connected correctly with neutrals in appropriate bars ,
head scratcher

 

[spark 68]

Slack Neutral ?

 

[markc123]

Odd - you sure it's not a coincidence and a completley unrelated fault...like a fridge kicking in maybe?Hav

Have you checked all connections are tight?

 

[glasgospark]

Tightened every connection in board , at shower and pullcord

- - - Updated - - -

It does it everytime , I even switched every breaker off except shower and it still does it

 

[Guest55]

swap the rcd's around and see if its still the same device that trips.
a fast way of verifying both rcds without all the usual faffing around.

 

[glasgospark]

You thinking faulty rcd , can't understand it , shower on left tripping rcd in the right

 

[Guest55]

im not suggesting anything , but its a quick way of ruling out a faulty rcd before pulling the wiring apart.

edit ;
and hi to spark 68 , long time no see.

 

[glasgospark]

Why would a shower on a dif rcd trip the other rcd but shower stay on , baffles me

 

[stuartcourt]

Hi only ever had couple of times both with MCG board and both times I did have a neutral crossed worth one more look ?

 

[telectrix]

but it's been fine for 6 months, so either there's a weird fault developed, or someone's been having a go.

 

[Paul.M]

Have you done an IR test yet? Could be the cable tripping the RCD under high(ish) loads???

 

[glasgospark]

Yeah seriously weird I done job in September , done full test before board change then rcd tests after , its a Hager board
if it was a crossed neutral or something obvious it would have done it at home time in September

 

[glasgospark]

the shower cable is 6month old , and its tripping the other rcd not the rcd protecting the shower circuit plus shower stays on ,

 

[markc123]

Maybe Caspers pressing the T button.

 

[telectrix]

grasping at straws here, but could the shower have developed a leak, perhaps from the waste, and is wetting another circuit, under the floor, maybe?

 

[Paul.M]

Have you done an IR test now and compared it to your EICR from when you fitted it? Also do a continuity test in-between both neutral bars just in case someone has tapped into a circuit since installed.

 

[Guest55]

well if all things being equal , and no changes to the wiring.............

then the shower is still faulty no matter how many elements the repairman replaces.
;-)

 

[glasgospark]

Doesn't explain why it only trips on high mode :O

 

[snowhead]

It does it everytime , I even switched every breaker off except shower and it still does it

Take out all the neutrals on the other RCD as well as switching off the Mcbs.
Then put each circuit back in 1 at a time

 

[glasgospark]

Yeah , its the shower that's faulty no doubt , but it should be tripping its own rcd not the other one and staying on

 

[Silly Sausage]

This is a real vague shot in the dark...!!!!!!
Is the shower cable running tight alongside another connected to the other side of the board and inducing a current in that cable's Neutral???
Have you tried clamping each circuits Neutrals on the tripping side, when the shower is on max?


Clutching at straws here!

 

[glasgospark]

Ill try that , I went today for 20mins to double check my work basically to rule out it being my fault , although its been fine for 6 months so obviously a new fault but wanted to show face

 

[Guest55]

Doesn't explain why it only trips on high mode :O

it does , it indicates theres a fault with electronics , and changing the element will do sweet F.A.

 

[Paul.M]

Showers have two heating elements, when the second element kicks in that is when it trips so that is the fault. Check the internal connections of the shower before sending it back to the wholesalers.

 

[stuartcourt]

never knew that cheers

 

[KevinS]

I had a 16th ed board, where the lights were not protected by an RCD, but if you turned the lights on off quickly it tripped the RCD in the board (even tho they weren't connected to it).
Swapped the RCD (even tho it seemed ok)
Problem solved

i would try changing the RCD

 

[glasgospark]

We didn't supply the new shower only rewired , customer didn't want to change it , Triton guy been out to replace element

- - - Updated - - -

Did you find out why that happens

 

[glasgospark]

I had a 16th ed board, where the lights were not protected by an RCD, but if you turned the lights on off quickly it tripped the RCD in the board (even tho they weren't connected to it).
Swapped the RCD (even tho it seemed ok)
Problem solved

i would try changing the RCD

did you find out why that happend

- - - Updated - - -

The second element ?

 

[itselectric]

I would check the offending rcd. It sounds to me that either the two poles are not making properly when switched on or a loose connection maybe on the ingoing side.

 

[glasgospark]

I would check the offending rcd. It sounds to me that either the two poles are not making properly when switched on or a loose connection maybe on the ingoing side.

Even if its totally fine until shower switched on to high though

 

[Paul.M]

Even if its totally fine until shower switched on to high though

2nd element in the shower kicking out an earth leakage. Clamp meter the 10mm CPC at the CU whilst someone turns the shower onto full and see what the readings say.

 

[peterb]

Could be spikes from the electronic control causing currents to flow through capacitive filters on for example a washing machine. Have they got a new washing machine etc recently. Best way to test this is to unplug all the appliances and see if fault goes away. Just disconnecting the live doesn't work as they have capacitors N-E too and there could be spikes on the neutral too. had this problem once where spikes from church SON lamps tripped RCD in adjacent house.....Hope this helps

 

[bigbaddave]

What is current rating on the RCD? Not MA..

 

[glasgospark]

What is current rating on the RCD? Not MA..

63 amp I think , but it done it with everything else in house off only shower mcb on still does it

 

[Rampantchilli]

I've come across a very similar fault, someone had done a board change and everything worked. Now and again, when the Rcd tripped it would trip both or only one, with a full test I found both ring mains interconnected across both rcds. Main reason I was called to site was because when an Rcd needed resetting you had to turn each CB off and both rcds. The install actually functioned fine most of the time, albeit not very safely.

In my 22 years experience I've found 95% of the time, the simplest and most obvious answer is usually the right one. I'd start with checking continuity between the 2 neutral bars with CBs off then with them on, with power off of course.

 

[glasgospark]

thanks m8 will give a try

 

[BigSi]

[FONT=&amp]This thread reminds me of a Sherlock Holmes quote,”When you have eliminated the impossible, whatever remains, however improbable, must be the truth?”[/FONT]

[FONT=&amp]Here are a few things to think about.[/FONT]

[FONT=&amp]a) Has anybody else worked on the consumer within the six months?[/FONT] [FONT=&amp]
b) If you perform an RCD test, does the RCD’s correspond with the circuits tested?[/FONT]
[FONT=&amp]c) Is the second RCD feed from the first RCD (non time delay)?[/FONT] [FONT=&amp]

I know they are long shots, but at least we can eliminate them from the list.[/FONT]