Tripping RCD on shower, Not knocking the supply off.

[enrabark]

Hello.

I have been called to a mates flat due to concerns about a faulty shower (despite having a limited knowledge of domestic installations)

Basically whats happening is when he turns the shower on it trips the RCD in the consumer unit, but this doesn't knock the supply off to the shower... the red light stays on and the shower still runs hot.

When i tried to test the RCD with the 'T' button, it didnt operate. Im assuming this isn't correct. But looking at how the RCD is wired up i dont know how it would ever turn the shower supply off, as it doesnt appear to be in series with the load.

Its puzzling that it will operate when the shower gets turned on, but not trip when tested. I suspect that the landlord may have been tinkering as i noticed that there other electrical issues (no earth bonding on the pipes etc.)

Anyone with any thoughts please let me know, id appreciate a bit of help.

Cheers!

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• enrabark
• 28 Apr 2013
• 1

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• enrabark
• 28 Apr 2013
• 1

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• enrabark
• 28 Apr 2013
• 1

 

[Adam_151]

Is there a break in that busbar? Guessing not!

EDIT: Just seen the 2.5mm linking the neutral blocks.

That RCD isn't actually protecting anything! and the 2.5mm between neutral blocks is at risk of serious overload

 

[enrabark]

nope im pretty sure it runs straight though. starting to think that its been wired up incorrectly.

 

[xr4x4]

Assuming its allowed, I would remove the main switch and put the rcd in its place.

This way the lives can come in at the top of the rcd, live to the busbar and neutral to the neutral bar.... With 25mm2 cable! And a solid link between the neutral bars.

 

[enrabark]

Ok, thanks for the input. I've read my onsite guide a bit more, and asked a few colleagues. this is what I think i will do.

Im going to cut the busbar pretty much bang in the middle and separate the two circuits, then have the RCD feed the sockets and shower. allowing the lighting to be fed from MCBs only.

Can anyone see a problem with me doing this to his board (see pic)

Also i heard that the MCBs should stack lowest to highest, in the direction of the RCD, didnt really understand this is it important?

Any tips or ideas again, very much appreciated. especially anything which looks like im doing something unsafe. Cheers

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• enrabark
• 2 May 2013
• 1

 

[xr4x4]

How will that conform to the 17th ed?

 

[eveares]

While I am not part P certified; what I would do is replace that 60A 30ma RCD over with a 100A 30ma RCD and put all the circuits on it.

The 17th edition states all circuits should be RCD Protected.

I would also put a warning sticker on the box, to inform of mix old and new wiring colors. http://www.tlc-direct.co.uk/Main_Index/Cable_Accessories_Index/Cable_Colour_Labels/index.html

 

[bernardgreen]

The best advice is to get the landlord to employ a registered / qualified electrician to repair the dangerous installation.If he refuses then your mate needs to contact the building control department of the local council and make the clear point that the essential safety device on the shower is not working.

Contacting the council may put his tenancy at risk if the landlord is a dubious / dishonest person but as things stand his life and that of other people in the flat may be at risk.

 

[Spark123]

The RCD trips when the shower is used as the impedance of path through the neutral side allows enough current through to trip it, the neutral path through the RCD is in essence in parallel with that small piece of 2.5mm blue wire.
Some current passes through the blue wire, some passes through the RCD neutral side. Hit around 30mA through the RCD and it trips.
The test button places a resistor across the RCD "L in" to "N out". As the RCD has in effect got two L&N feeds, one in the top and one in the bottom then pressing the test button probably isn't passing enough current through the sensing coil hence doesn't work, that is providing it hasn't fried the resistor!!

As others have said, get the landlord to employ an electrician to sort it out. It is probably DIY as anyone calling themselves an electrician who did that wants sacked pronto!

 

[ban-all-sheds]

Hello.

I have been called to a mates flat due to concerns about a faulty shower (despite having a limited knowledge of domestic installations)

What electrical installations do you have knowledge of?

 

[ericmark]

I would not touch the installation I would only report it as faulty. Trying to cut the buzz bar and so getting the RCD to work on some circuits can open up a can of worms where lights have shared neutrals etc. There is likely a reason why the buzz bar was not cut and likely that is because there are faults in the house which will trip the RCD once cut. Tracing those faults can be a nightmare and once you fiddle the landlord will likely blame you for all of the faults.

Likely the landlord does not know there is a fault likely it was some one claiming to be an electrician who did the work some time before 2008 so at least 5 years ago.

 

[ricicle]

Has this shower been installed recently ?
Looks like a dangerous fool has been messing with the consumer unit

 

[Spark123]

Looks to me like a dangerous fool installed the consumer unit!!

 

[ericmark]

Looks to me like a dangerous fool installed the consumer unit!!

I would tend to agree but my point is the landlord may be unaware of this and until the landlord has been made aware and there has been some reply nothing should be done.