Two wall sockets keep tripping the fuse box.

[mediter]

Dear friends,

Five years ago I did an extension to the house which includes a bedroom upstairs. It has two wall double sockets and I was always aware that mostly anything that is plugged into them trips the corresponding fuse within the newly installed fuse box downstairs. Items that may not trip the fuse are small things such as a phone charger or low light shades (although in these cases their own fuses may blow instead), but anything like Vacuum cleaner, hairdryer, etc will trip it instantly.

After completely disconnecting the electricity of the entire house opened the wall sockets thinking perhaps there is a short but it all looks nice and clean. I am wondering if the problem lies within the fusebox downsairs. The fuse that trips, only covers those two sockets, any thing else works fine, both from the extension and old building.

Your advise is most appreciated. Thank you so much.

 

[winston1]

Why have you left it 5 years? You could have got it fixed for free by the original sparks. Is it a MCB or RCD or RCBO that trips?

 

[davelx]

Being psychic, I predict that:
a) there was no original sparks
b) it's an RCD that's tripping and
c) it's due to an incorrectly connected neutral

 

[mediter]

Thank you for your replies. The room was not used much so I did not know how big the problem was. davelx is right, there was no sparky because the guy who did the electricity was nothing but a pretend one. Could not follow him because first of all it was too late and also, later he spent months in hospital playing with death. The only time I found out he was not a sparky is when he sent someone to sign for his work, but upon checking it the true sparky realised it was grossly flawed. Then was asked to correct it at the cowboy's expence. However, I take it the upstairs room in question must have missed the proper tests. I remember the sparky who made the corrections downstairs was shocked to see there was no earth in the kitchen sockets. So I think the pretend sparky is worse than one can imagine.

When I opened the sockets I did find the wires in the right place, so could neutral been incorrectly connected at the RCD?

Please look at the picture, it shows the tripped circuit breaker.

 

[Taylortwocities]

Unfortunately we do not have X-ray eyes! Need to see the wiring with the cover off!

Also, which of the 5 MCBs is the one that switches off the sockets?, and which of the grey switches "trips"?

 

[mediter]

It is the middle one, No. 3 as seen in the image. Ok, I opened the box and all wiring seems ok, nothing loose and all corresponding wires in the right place.

So while there with the RCD uncovered I disconnected the wiring of the upstairs room in question and connected it to the Circuit Breaker of the downstairs sockets (which never failed). It worked perfectely, testing the Vacuum cleaner. No tripping. Hoorraah!

So is it the circuit breaker defective or perhaps more plausible the fact that it is a 6Amp as against 32 Amps as the one that worked? I think 6 Amps is quite low for two double wall sockets, considering connecting a vacuum cleaner or a hairdryer would need at least 10.

So in brief: Original connection to NSB06 tripps, but connecting to NSB32 works.

So if the NSB06 is deemed too low which is the recommended one?

Are we getting somewhere now?

 

[Taylortwocities]

The problem, as you say, is that the MCB is too low for the load.

So if the NSB06 is deemed too low which is the recommended one

The size of teh MCB depends on the thickness of the wiring, and the type of circuit, so we need to see the connections to the top of that MCB to judge what size the MCB should be.
The "electrician" may have put in a 6amp MCB for a reason.


PICTURES PLEASE!!

 

[winston1]

How many wires are on the MCB. If only one it's a radial circuit and it would expect it to be 20 amps. If there are two wires it could be a ring which would normally be 32 amps. But without checking it may not be a ring so to be safe put in a 20 amp.

 

[canduit]

How many wires are on the MCB. If only one it's a radial circuit and it would expect it to be 20 amps. If there are two wires it could be a ring which would normally be 32 amps. But without checking it may not be a ring so to be safe put in a 20 amp.

Do not put in a 20 amp! This could have previously been a lighting circuit that a numpty has converted to a plug socket circuit. Or it could be anything; no way of telling without test gear and knowledge

 

[Iggifer]

Do not put in a 20 amp! This could have previously been a lighting circuit that a numpty has converted to a plug socket circuit. Or it could be anything; no way of telling without test gear and knowledge

For an extension, unlikely. If it's 2.5mm² and the OP has not noticed anything else not working whilst it's been off, then it's fairly safe to say the muppet just used the wrong breaker, either because a) he didn't know any better or b) bought a pre-populated board and couldn't be bothered to get the correct MCBs

 

[Iggifer]

What on earth is going on with those tails in that picture? What a dogs dinner, more blue on show there than I have on show inside a consumer unit

 

[canduit]

Unlikely but entirely possible considering kitchen sockets weren't earthed

 

[Iggifer]

I still vehemently disagree, the chances of that being what's happened are infinitesimal.

We shall wait and see what size the OP says the cable is, but I'd back it being >2.5mm² all day, every day.

 

[mediter]

Thank you so much for all your help in such a short time.

Here is the picture and the MCB in question is the one in the middle, tripped, with one wire going in.

 

[Iggifer]

2.5mm² on the suspect circuit.

That is a dogs dinner in there!

I take back my statement about it being a pre-populated board, that offending 6A was clearly knocking around in the back of his van for a while, just wanted to get rid!!