Urgent RCD Trip - Holiday disaster - Help Needed

[martin252]

Hi Guys

Got home last night all electrics off. Fridge - Freezer the whole works.

With all MCB's switched off I can switch on consumer unit.

Tried to isolate problem and switch off all appliances. Every time I switched on 32amp MCB's it blew. Had a little success with one of the lighting MCB's but after a while it blew again.

Later I managed to switch on a couple of 32Amp MCB's but then they blew after a short while without switching any appliance on.

The biggest reaction is to a 32amp MCB supplying kitchen etc..... generates a small flash when switched on.

My thoughts but I am no electrician:

Could be the RCD but think that is very unlikely.

Last time it was mice chewing cables and one even electrocuted itself in the consumer unit!

Is there any way I can check whether a mouse has compromised the earth wire somewhere on these circuits - some sort of meter I could buy and plug in the sockets?

Any ideas or assistance much appreciated.


Thanks

Martin

 

[martin252]

Wire chewed through for garden pond pump....caused a small fire..lucky this time...will use armoured cable to replace.

 

[ban-all-sheds]

Who was the muppet that used non-armoured cable in the first place?

 

[tricia]

Hi Guys

Last time it was mice chewing cables and one even electrocuted itself in the consumer unit!

Is there any way I can check whether a mouse has compromised the earth wire somewhere on these circuits - some sort of meter I could buy and plug in the sockets?

Any ideas or assistance much appreciated.

Martin

Have you solved your problem yet?

Well, anyway, I am no electrician either, but as you sound desperate I'll give you
my 2 cents' worth.

In short, I reckon that there must be some kind of shorting-out occurring INSIDE the
consumer unit, perhaps by a bared wire that runs passed many MCBs???
I say this since you report that many MCBs are tripping, and AFAIK one MCB
should not affect another, ideally.

I can't see why an _earth_ fault elsewhere in your house would cause this problem
because the MCBs detect overcurrent through themselves, and why one earth
fault would affect multiple MCBs I am not sure. But I may well be wrong about this!

So, my wild guess stab-in-the-dark is that, yes, the mice are back inside
(or very near) the consumer unit! So start looking there, perhaps.

Hope that's of some use.

(P.S. Perhaps you could put a photo of your CU on this site, and also one of the
electrocuted mouse from the last time? )

 

[tricia]

Wire chewed through for garden pond pump....caused a small fire..lucky this time...will use armoured cable to replace.

Oh. Just seen your reply. Glad you've solved it.

 

[securespark]

Ban

The rodent may have masticated the flexible cable attached to the pump itself, thus sustaining a shock of sufficient magnitude to stop the wee beastie's cardiac system.

 

[ban-all-sheds]

Serves it right.

Don't understand though how a damaged cable on one circuit can cause other MCBs to trip...

 

[Lectrician]

This post is ******.

Switching a MCB off doenst disconnect the neutral.

With a neutral to earth fault (even a smal one), current will flow from N to E and cause the RCD to trip - FACT.

The more load you turn on, the easier the RCD will trip with a N to E fault.

If it trips with ANY of your MCB's on, then it IS a N to E fault on ANY circuit, suspect outside ones etc.

WHY do you have an RCD protecting the WHOLE board????????? That is a DIY'er's or sh1t electricians way of doing it (unless TT ).

 

[securespark]

True, mcb's DON'T iso the neutral. BUT, turning off mcb's often is enough to allow the rcd to reset.

Are you saying any energised mcb can trip the rcd, even if the fault is on an mcb that is isolated?

So the fault I'm investigating at the mo (tripping rcd on a spur that is not being used - when the circuit mcb is iso'd, the rcd resets) means it might not be that circuit at all?

 

[ban-all-sheds]

This post is ****.

Switching a MCB off doenst disconnect the neutral.

With a neutral to earth fault (even a smal one), current will flow from N to E and cause the RCD to trip - FACT.

The more load you turn on, the easier the RCD will trip with a N to E fault.

If it trips with ANY of your MCB's on, then it IS a N to E fault on ANY circuit, suspect outside ones etc.

WHY do you have an RCD protecting the WHOLE board????????? That is a DIY'er's or s**t electricians way of doing it (unless TT ).

This is all true.

What I was curious about was not the way the RCD was tripping, it was this:

Later I managed to switch on a couple of 32Amp MCB's but then they blew after a short while without switching any appliance on.