MICC/PYRO. CABLE FAULT. / FUSE NOT BLOWING

[MOGTARYAN]

Hi. I have a question about MICC/PYRO cable.
I have only very rarely worked with this type of cable , I've mostly worked in domestic wiring.
However the other day a friend asked me to change a faulty single socket for him, ( piece of cake). It didn't turn out to be !!!
He lived in a flat built in the 1960's and it was wired in MICC cable. A ring main . Protected by a rewirable 30 amp fuse.
I fitted a new single socket and as I screwed the socket back, I nipped one of the cables and caused a short! I said to my friend, don't worry, done that a few times, and went to change the fusewire. Fusewire still intact ( and correct size ).
I have a few theories on what has happened, but would like to here others points of view.
What is the lifespan of MICC cable?
Cheers!!!

 

[Pete999]

Hi Mate, firstly what are the theories you speak of? you say you nicked the cable and caused a short, may seem a daft question but how do you know nicking the cable caused the "short circuit"?

 

[Deleted member 9648]

So you changed the socket live?
If I'm reading this correctly there was a bang as you screwed the socket back but the fuse didn't blow?

 

[Pete999]

So you changed the socket live?
If I'm reading this correctly there was a bang as you screwed the socket back but the fuse didn't blow?

Never crossed my mind that he would work live!!!!!!!!!

 

[MOGTARYAN]

Cheers, correct, pulled out fuse, changed socket, replaced fuse, socket just needed tightening slightly, when bang occurred.

 

[Octopus]

Pulled the wrong fuse?

Old BS 3036 fuses don't always go when a short circuit happens briefly!

 

[Bobster]

What is the Zs of the circuit.

Also, MICC has a lifetime well in excess of you or me if installed properly.

 

[MOGTARYAN]

Hi, thanks for the feedback.
I was definitely pulling the right fuse by the way.
I think my friend may have confused the situation as there is only 1 ring main in the flat. (It is a duplex, so has an upstairs ). He told me ,none of the sockets upstairs were working, ( it was late at night, when this happened) so I took his word for it). I now believe that some sockets were live, which alters the game, as I was looking at a ring main with a fuse in and in my mind no power to any sockets. Thanks for the comment about Zs, unfortunately my friend lives miles away and I only had a couple of tools on me, I've rigged up some temp power for his essentials, but when I see him again will investigate further.
Thanks for all your help, great site this and I would welcome any more suggestions.

 

[westward10]

Was refitting a trunking lid many moons ago nicked a conductor big bang, blew a hole in the lid while the 3036, 60A fuse just laughed at me.

 

[MOGTARYAN]

Westward 10, nice one, I bet that woke you up!!

Was refitting a trunking lid many moons ago nicked a conductor big bang, blew a hole in the lid while the 3036, 60A fuse just laughed at me.

 

[PEG]

Hi, thanks for the feedback.
I was definitely pulling the right fuse by the way.
I think my friend may have confused the situation as there is only 1 ring main in the flat. (It is a duplex, so has an upstairs ). He told me ,none of the sockets upstairs were working, ( it was late at night, when this happened) so I took his word for it). I now believe that some sockets were live, which alters the game, as I was looking at a ring main with a fuse in and in my mind no power to any sockets. Thanks for the comment about Zs, unfortunately my friend lives miles away and I only had a couple of tools on me, I've rigged up some temp power for his essentials, but when I see him again will investigate further.
Thanks for all your help, great site this and I would welcome any more suggestions.

Hi bud,never,ever "take a word",from a tramp or a judge.Late? Miles away? Few tools? Does not matter.

Assess the situation yourself. If some sockets were working,and some not,you have two circuits,and if needed,you should have isolated both.

Micc is like railway track,it will function without issue,for generations,with us hardly noticing it.

 

[Deleted member 9648]

Hi bud,never,ever "take a word",from a tramp or a judge.Late? Miles away? Few tools? Does not matter.

Assess the situation yourself. If some sockets were working,and some not,you have two circuits,and if needed,you should have isolated both.

Micc is like railway track,it will function without issue,for generations,with us hardly noticing it.

Try telling that to the poor sods using Southern Rail!

 

[mache]

Slightly concerned on the comment 'said to my friend, don't worry done that a few times' !!!!
Has the phrase learn from ones mistakes taken a back seat these days ??

 

[westward10]

Just looked up the word "friend", knew my life was missing something.

 

[Sam cook]

It's a shame the industry has moved away from MICC cable, may prevent persons who shouldn't be dabbling with electrical circuits, we find caretakers one of the worst. I think I made 2 ends on a piece of pyro in college then luckily we secured some heritage work which allowed me to dress and make of some MICC cabling. I remember as a kid helping my dad in the summer holiday with school works which you could do then and helping him remake a Imperial MICC sub main cable. To a new Distribution Board we were installing was Memsheild 2 gear then.