Problem with spur

[asalcedo]

I was making one spur from a power socket as I have done many times.

I did not switch off the electicity and accidentally shorted with th screwdriver the life and the earth copper terminals. There was a bi blast and some melting of the tip of the screwdriver but the circui breaker in the consumer unit for that circuit went off as supposed to.

When I finished the job and restored power at the circuit breaker everything in the circuit is working, except for that socket. There i no power there.

I have tested the voltage and there is 3.6V in this socket between lif and neutral and about 0 between neutral and earth.

The actual cable looks fine.

What has happened, how can I solve it?

I cannot access the junction boxes. They are behind fixed kitche furniture that cannot be removed.

Thanks,

Antoni

-- asalcedo

[TMC]

Perhaps short it with your fingers next time probably wouldn't damage the socket or wiring then

However if you insist on taking unnecessary risks completely disconnect the socket and test the incoming cables if there is no current there investigate further back in the wiring.

best not to ignore the problem as there is no telling what may be happening further back

or check that your house insurance is up to date and keep your fingers crossed

Tony

[The Natural Philosopher]

You blew the cable probably. Somewhere hidden. Replace it.

Try a sledge hammer. That will remove most things. The ideal antidote to Ikea.

Otherwise you will have to route the cable some other way.

[Andy Champ]

I'd say you've connected the live to the neutral, and you're lucky you don't have fragments of melted screwdriver in your eyes.

Have you considered professional help?

Andy

[Ian_m]

My mate once did the same whilst adding another double socket in the kitchen, without turining power off (actually he turned power to the other house ring rather than kitchen). Remember shorting a ring trips at 32A not

16A !!!

He thoughtfully checked both "sides" of the ring where he had shorted and one side had no live. I helped him confirm this as well. Disconnect both the ring L & N at the CU and connect together and resistance check at socket that they are shorted, one side of ring wasn't in his case. He removed the kitchen cupboards and cut the cable out from behind the plasterboard and luckily for him the broken wire was at top of wall where it made a sharp bend across the ceiling. The live had blown a hole in the cable. The fault was probably caused by the cable being too tight, he did assure me that he hadn't pulled the cable down to extend the spur, so might have had the weakness since kitchen was built.

Anyway cut away section of ceiling added a junction box and new section of cable made good the repairs and got his mate to properly test the ring to verify that there were no other issues.

Using the new sockets his toaster worked fine until it burnt the units it was installed under !!!!

[Andy Burns]

Actually it'll take several times the rated current to "instantly" trip the MCB, assuming a type B32, between 100A and 150A.

[James Salisbury]

And the actual fault current could be 100s or 1000s of Amps!

[jlspam1]

Alas, I will second the other posters - get professional help and resign yourself to having to remove the cupboards to get at the fixed wiring.

A professional will no doubt remove that ring from the CU and perform quick basic tests to to confirm what people suspect that there is something seriously amiss with that ring. With the correct test gear it is possible to check all points on ring and determine the condition of the wiring - without it you might as well resort to a ouija board or downing.

Put simply - until that ring passes basic loop tests, insulation tests and a RCD test you are taking your life in your hands by using it. A short like that has a tendency to find any weak spot in your circuit and exploit it.

Even if it seems OK you have no idea if the insualation is badly damaged enough to cause a fire whilst you are sleeping.

*Only* by using the correct test equipment will you know that.

Unless you are an extremely profficient DIYer and own a multimeter, insulation tester and RCD tester (and know how to use them) - you

*CANNOT* solve this issue without remaining in doubt that your house will burn down as you sleep.

Sorry to put a dampner on your evening, but thats my 2 cents.

[asalcedo]

I really find this derogatory and aggressive tone in many of th replies very sadly typical of many of the posters in this forum.

It turns out that I am an engineer with far too many years of academi and professional experience and who knows about electricity more tha just a thing or two. That is why I was willing to take the risk.

I was asking because I did not know what had happened and none of th answer here found it.

Anyway, the problem is fixed. Just a blown 13A fuse hidden behind som kitchen clutter.

A good quality electrical layout that placed fuses for the spurs. I wa taking the spur out of this spur, not a ring circuit. And yes, I kno the power involved and the diameter of the cable, the voltage an amperage required, and yes, I know that the extra load will never b more than about 10watts and used a 1mm diameter cable for the new spu as a consequence and bla bla bl

-- asalcedo

[John Rumm]

It might help if you provided the important details that you neglected to mention in your original post. Your description also did not inspire confidence since most skilled electricians would not usually take unnecessary risk of working live when there is no overriding reason to do so, and when obviously not working with the correct tools and procedures to do this safely.

You sound surprised ;-)

Hardly surprising since your description was misleading. It sounded like you were adding an unfused spur to a ring final circuit. The nature of the fault you then described would suggest that the ring continuity had been compromised - hence the concern expressed by some of the responses.

So you were actually adding another socket to an existing fused spur. In which case no problem.

1mm diameter cable?

Twin and Earth with conductors of at least 1.5mm^2 would have been appropriate (assuming this is fixed wiring, and not an appliance flex connected to a FCU that you are talking about).

[jlspam1]

I really find this derogatory and aggressive tone in many of the replies very sadly typical of many of the posters in this forum.

sorry if you feel that way, not trying to be insulting. check my other posts I am trying to rewire my entire house and have commented on the same thing.

out of interest, if you were adding a new socket to a fused spur, at the very least you could of simply removed the fuse the spur if you could not be bothered to properly isolate.