Help, circuits may be crossed somewhere ?

[LeeDowner]

I was installing a new socket today and during this process I managed to blow the 30amp fuse for the circuit I was working on (no I wasn't working live, it blew when I turned the power back on). I changed the fuse wire and all was fine.

But later on, I noticed a socket was dead that was definitely not dead before I blew the 30amp fuse. Upon further inspection I discovered that this particular socket appears to be alone on a 15amp fuse, separate to the rest of the house, and that 15amp fuse had also blown presumably at the same time the 30amp fuse blew.

I don't understand how two seemingly separate circuits could blow their fuses at the same time, I thought I was only working on the 30amp circuit, could they be crossed somewhere ?

I don't think it's relevant but I'll put it out anyway, the cable supplying the socket that died is the old cable that has many different strands, I'm afraid I don't know what it's called.

 

[EFLImpudence]

(no I wasn't working live, it blew when I turned the power back on).

Do you know why?

I thought I was only working on the 30amp circuit, could they be crossed somewhere ?

Anything is possible. Have you any testing equipment?

I suppose there are two lives (reds) connected to the 30A fuse, are there?

cable that has many different strands, I'm afraid I don't know what it's called.

Stranded.

 

[LeeDowner]

What do you mean about having two lives connected to the 30A fuse ? That fuse supplies the whole power circuit ?

It blew because the new socket I installed wasn't connected properly when I turned the power back on.

Thanks for the reply.

 

[EFLImpudence]

If it is a 'usual' ring final circuit there will be two wires (2.5mm²) running to the 30A terminal - (not the fuse itself, bad wording before).
Not conclusive though, it could be a radial final circuit with only one wire but this would mean the wire would have to be thicker (4mm²).
Can you tell the difference?

Because of the other fuse (15A) blowing as well, sometimes we come across a ring with one wire in one fuse terminal and the other in another - not a good idea.

 

[LeeDowner]

If it is a 'usual' ring final circuit there will be two wires (2.5mm²) running to the 30A terminal - (not the fuse itself, bad wording before).
Not conclusive though, it could be a radial final circuit with only one wire but this would mean the wire would have to be thicker (4mm²).
Can you tell the difference?

I'll check out both fuses and the terminals connecting them.

Because of the other fuse (15A) blowing as well, sometimes we come across a ring with one wire in one fuse terminal and the other in another - not a good idea.

Why would someone do that ? And what are the potential dangers ?

 

[rjm2k]

If it is a 'usual' ring final circuit there will be two wires (2.5mm²) running to the 30A terminal - (not the fuse itself, bad wording before).
Not conclusive though, it could be a radial final circuit with only one wire but this would mean the wire would have to be thicker (4mm²).
Can you tell the difference?

I'll check out both fuses and the terminals connecting them.

Because of the other fuse (15A) blowing as well, sometimes we come across a ring with one wire in one fuse terminal and the other in another - not a good idea.

Why would someone do that ? And what are the potential dangers ?

By mistake, potential danger?, you think you've isolated the circuit you are working on by switching off the "fuse" but the other one is still live! Or, you blow 2 fuses in 1 go by incorrectly wiring up a socket and switching the power back on. Did you isolate just the 1 circuit or the whole lot?

 

[LeeDowner]

Another slightly separate question, I have a security light which is being powered by the previously mentioned 15A circuit via a fuse spur off the socket that the 15A circuit goes to. Is this correct ? Or should the security light be on a lower powered circuit (lighting circuit) ?

 

[LeeDowner]

RJM: I had only disconnected the 30A fuse as that was the circuit I was installing the new socket onto, all other circuits were live. after pushing the fuse back into the fuse board and turning the power back on, the 30A fuse blew because the cable supplying the new socket wasn't correctly terminated.

 

[Chri5]

RJM: I had only disconnected the 30A fuse as that was the circuit I was installing the new socket onto, all other circuits were live. after pushing the fuse back into the fuse board and turning the power back on, the 30A fuse blew because the cable supplying the new socket wasn't correctly terminated.

Hence why testing for dead Is so important, never assume because its off, it's off.

A circuit that has some where mixed in with another would appear dead on fuse removal, but would still be live.


The fused spur you mention is fine provided it is fused down as low as needed for the cable and intended use (use a 1A fuse if less than 230w, 3A for 500w Eco burn the planet type lamp).

 

[ban-all-sheds]

It blew because the new socket I installed wasn't connected properly when I turned the power back on.

What did you do wrong?

I was installing a new socket today and during this process I managed to blow the 30amp fuse for the circuit I was working on (no I wasn't working live, it blew when I turned the power back on). I changed the fuse wire and all was fine.

Surely you mean you fixed the problem you created when you connected the socket, changed the fuse wire and all was fine?

 

[LeeDowner]

Ban all sheds, yes that's what I meant.

The new socket I installed is on the other side of a wall that's carrying an existing socket, right behind it so to speak.

It's embarrassing but I'm being pushed for an answer so I'll answer it; The fuse blew because the new cable was still halfway through the wall when I turned the power on, I needed the power to be on so I could use my drill and I don't have an extension long enough to reach my cooker circuit which was the only circuit left live that could power my drill. So the cable came into contact with the brickwork.

 

[Scoby_Beasley]

It's embarrassing but I'm being pushed for an answer so I'll answer it; The fuse blew because the new cable was still halfway through the wall when I turned the power on, I needed the power to be on so I could use my drill and I don't have an extension long enough to reach......

Not an ideal situation to be in but I admire your candour and honesty!!