RCD trips when shower is turned on

[Multiplex]

Hi ban,

It's not a faulty shower, as I've switched the two showers over and got the same problem.

But I just decided to swap over the RCCBs in the unlikely event it was faulty...and I've found that he wired them up differently!!! The one upstairs that works has the blue wire from the CU at the top, but the other flat's RCCB has the blue wire from the mains at the bottom (where the big fat bar thing is).

So my question is...is there just one way RCCDs should be wired, or can there be the possibility of it being wired in a different way????!!!!

Thanks!

Simon.

 

[brown-nought]

Ages ago or so it feels today - I sugested you get the original guy back to check his work. Ignore that advise - GET SOMEONE ELSE!

Before you were fiddling with the wires thinking the circuit was isolated when the fuse was actually out for the other shower - you were probably playing with a live circuit!.

 

[Multiplex]

I know...! I really appreciate the advice I have received from everyone here, and I realise I've obviously put myself at risk given what we now know about this wiring.

And the electrician isn't answering my calls...so I'll do this one myself as I know the problem now.

Will let you know when/if it works.

Simon.

 

[plugwash]

with a mcb (overcurrent only) only live goes through it

with a rcd (earth fault only) live and nuetral enter together on the one side (generally the top) and leave together on the other (generally the bottom) live generally goes to a busbar to mcbs neutral generatlly goes through a cable to a busbar there may be a conenction to the earth bar as well (if the rcd is dc sense) this will be cream the color for functional earth and will generally be hard wired in at the rcd end

with a rcbo (which protects against both for a single cuircuit) which is what it sounds like you have live enters at the bottom from the busbar like with a mcb neutral enters in most cases via a flying lead although there is sometimes a terminal earth enters via a cream lead from the earth bar
live and neutral both exit to the cuircuit from the top

if in dout post some photos and we can tell you with certanty

 

[Multiplex]

Here's a picture of it:

The box says it's an RCCB.

The (working) upstairs flat is wired like this:
From CU:
Blue to third connection, top.
Brown to second connection, top.
From shower:
Blue to third connection, bottom
Brown to first connection, top.

The non-functioning flat is wired like this:
From CU:
Blue to third connection, bottom.
Brown to second connecton, top.
From shower:
Brown to first connection, top.
Blue to third connection, top.

If the working flat is wired correctly, I'll change the non-working flat to the same wiring then.

Simon.

 

[plugwash]

ok you have a seperate mcb and rcd connected together there i presume theese were mounted in a seperate enclosure from the CU?

yeah seems on the second one he got the neutrals the wrong way round firt one seems right

exactly what in the original CU did he connect them to and using what cable?

 

[securespark]

As plug says, he seems to have got neut's mixed up. On most rcd's it does not matter whether top conns are power in and bottom are power out, but you must pair up the conductors correctly, ie N in paired with L in.

In this case, he's put the outgoing neutral (to shower) with the incoming live (from CU), at the top.

At the bottom, he's paired the incoming neutral (from CU) with the outgoing live (to shower via mcb)

Swap the neutrals around and see what happens....

Plug has a point... The cables feeding the shower CU should really be fed from a henly block with proper DI tails of appropriate rating.

 

[Multiplex]

Well I've just finished rewiring (including laying new cable because the old wires didn't reach)...

AND IT WORKS!!

Finally, after much sweat it's all sorted.

For anyone skimming down the thread, the problem was with the showers connected to the wrong CUs and the RCCB had its neutrals connected the wrong way round.

The electrician, for what it's worth, was a nice guy who advertises with a very professional looking website. He didn't come across as a cowboy, rather an electrician who's still learning! But I think I probably got what I paid for...

Thanks,

Simon.