Anyone can fix an MICC cable leading to a light switch in my house (London, N6)?

Deleted member 148954 · Sep 12, 2022

Hello, I am looking for an electrician who has an expertise in dealing with MICC (mineral-insulated copper-clad) cables. It is a domestic job in my house (I live in Highgate, London; postcode is N6). When I was replacing a light switch in my living room, 2 out of 6 wires coming out of 2 MICC cables (which come through the wall; each cable has 3 wires) broke off. I am attaching two photos of the light switch in question (the 2 wires that have snapped are behind the switch). Please contact me if you can do the job and provide a quote. (If you need any further info, please let me know). Thanks, Eugene

Lucien Nunes · Sep 13, 2022

I also wondered at first whether there were dings in it, but now I'm more inclined to think it's an artefact of the pic.

davesparks · Sep 13, 2022

Lucien Nunes said:
I also wondered at first whether there were dings in it, but now I'm more inclined to think it's an artefact of the pic.

I reckon it's had an intimate encounter with the chisel used to dig the hole in the wall.

Deleted member 148954 · Sep 13, 2022

davesparks said:
That's exactly what I was thinking when I asked for a pic inside the switch. dig the old compound out, solder some extensions on and re-seal. I'd be game for giving it a go if I had time.

I don't know what the size is but the smallest imperial size MICC I've worked with is pretty tiny and easily snappable

Here are the pics of what's behind this switch. Hopefully they help figure out what could be done here. Thanks again for your help.

Lucien Nunes · Sep 13, 2022

It's a pity we can't see the seal discs clearly or exactly where within them the conductors have snapped. But scaling the size off the pic compared to the box and cable, I am increasingly convinced that they are 5/8" seals on imperial cable. If the existing seals can't be salvaged and re-used, metric pots can be fitted; it may be necessary to drill out the cable entry and solder to the sheath, according to the specific cable diameter.

@Eugene: Do you know what year the property was built / wired? Is the circuit protected by an RCD or RCBO? Could you tolerate the box being moved 5cm up the wall?

Slightly odd setup there, with two cores from one cable and one from the other going to each gang of the dimmer, but there are a number of reasons why that might have come about. Clearly some previous convictions with those bits of terminal block.

Deleted member 148954 · Sep 13, 2022

Lucien Nunes said:
It's a pity we can't see the seal discs clearly or exactly where within them the conductors have snapped. But scaling the size off the pic compared to the box and cable, I am increasingly convinced that they are 5/8" seals on imperial cable. If the existing seals can't be salvaged and re-used, metric pots can be fitted; it may be necessary to drill out the cable entry and solder to the sheath, according to the specific cable diameter.

@Eugene: Do you know what year the property was built / wired? Is the circuit protected by an RCD or RCBO? Could you tolerate the box being moved 5cm up the wall?

Slightly odd setup there, with two cores from one cable and one from the other going to each gang of the dimmer, but there are a number of reasons why that might have come about. Clearly some previous convictions with those bits of terminal block.

Thanks. The house was built sometime in the 1960s. Don't know about RCD or RCBO - there is a fuse box of course but that's all I know. Yes, the box can be moved 5cm up the wall.

UNG · Sep 13, 2022

littlespark said:
Have never know MICC to be used domestically except as a sub main up a tenement building in Edinburgh.

Sometime around the I think late 50's / early 60's BICC produced the Octpus wiring system which was used for wiring flats I believe it had a central box and all the cables were terminated into it this was laid out on the shuttering and the cables laid out to there various positions before the concrete was poured. A friend of my mum worked at the BICC factory in Prescot terminating the ends on piece work and was paid something like 3d per end it doesn't sound a lot but they could terminate upto 20 ends per hour. I remember seeing the film at college back in the 70's and it was amazing how they did it

Around Prescot you quite often find the odd older house wired in MICC usually the owner or past owner worked at the MICC part of the factory or were a relative of someone who worked there

ipf · Sep 13, 2022

I

UNG said:
Sometime around the I think late 50's / early 60's BICC produced the Octpus wiring system which was used for wiring flats I believe it had a central box and all the cables were terminated into it this was laid out on the shuttering and the cables laid out to there various positions before the concrete was poured. A friend of my mum worked at the BICC factory in Prescot terminating the ends on piece work and was paid something like 3d per end it doesn't sound a lot but they could terminate upto 20 ends per hour. I remember seeing the film at college back in the 70's and it was amazing how they did it

A penny a minute, 5 bob an hour, eh?
Must have been in the fifties UNG, maybe early 60’s, though.
I remember the octopus, they used loads in 60’s high rise flats.

ipf · Sep 13, 2022

Why the insulated lugs with metal screws in the switch back box?

It's still not clear to me where, exactly, the wires have broken.

7029 dave · Sep 14, 2022

Never liked this type of MICC clamp switch box, they were always shallow not designed for dimmers etc.
The better way would of been to use full terminations Micc glands then pot and coupler and bush into a standard deeper box .

ipf · Sep 14, 2022

7029 dave said:
Never liked this type of MICC clamp switch box, they were always shallow not designed for dimmers etc.
The better way would of been to use full terminations Micc glands then pot and coupler and bush into a standard deeper box .

I agree.... but when that one was designed the best description of a household dimmer was a lamp getting towards the end of it's life.

7029 dave · Sep 14, 2022

ipf said:
I agree.... but when that one was designed the best description of a household dimmer was a lamp getting towards the end of it's life.

Never got on with them stupid clamp (on the pot) accessories. Used them once that was enough

ipf · Sep 14, 2022

7029 dave said:
Never got on with them stupid clamp (on the pot) accessories. Used them once that was enough

Hey up......look what I've found. A church attic littered with them.

Installed correctly, they had their uses, I suppose

[ElectriciansForums.net] Anyone can fix an MICC cable leading to a light switch in my house (London, N6)?

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7029 dave · Sep 14, 2022

ipf said:
Hey up......look what I've found. A church attic littered with them.

Installed correctly, they had their uses, I suppose

View attachment 101651.

View attachment 101650

Nah would look better with a glanded MICC and stop end box , more expensive but a quality job lol

littlespark · Sep 15, 2022

Orange pvc coated MICC…. Now that’s a proper job!

Fire alarms in red as well?

Dustydazzler · Sep 15, 2022

I am certain that Del used on of those pancake pyro boxes on a job when he had to repair a damage pyro cable is a garage

7029 dave · Sep 15, 2022

Dustydazzler said:
I am certain that Del used on of those pancake pyro boxes on a job when he had to repair a damage pyro cable is a garage

Yup he did, dont know why he didnt use full terminations into a conduit through box or AB.
Looks the bees when using PVC coated orange and shroud if you please. lol
Maybe Del could not source gland.

UNG · Sep 15, 2022

7029 dave said:
Nah would look better with a glanded MICC and stop end box , more expensive but a quality job lol

I have always thought those boxes made it look like a cheap job and wasted the effort exerted installing the cable, it's a bit more of a complete job when MICC is glanded looks more reassuring

littlespark said:
Orange pvc coated MICC…. Now that’s a proper job!

Fire alarms in red as well?

When it was manufactured in Prescot you could get MICC with any colour serving you wanted if you were prepared to order the minimum quantity which was if I remember 3000m

When BICC manufactured MICC in Prescot they would even supply imperial sized glands and seals which were metric sizes drilled to imperial size

littlespark · Sep 15, 2022

I just remember years ago, it think it was going to be a museum or something... general power in orange, fire alarms in red and i think emergency lighting in white.

Apprentices jobs were to stand at the board and basically strip 2-3 foot off each cable as it came into the plant room.
Every day for a week coming home looking like Casper the flippin' ghost!

I think last time i even touched pyro was running a non-stop 500m length through the bowels of Ninewells hospital in Dundee.

There were more corridors under the hospital than appear above ground...

Spooky place sometimes.

Dustydazzler · Sep 15, 2022

I have only ever worked with bare and orange pyro

But I am certain I have seen white , grey and red pyro

I still remember clear as day being at a church we were adding some emergency lights and I came across pyro for the first time ( other than at college ) and my heart sank when I had to work on the old pyro circuit , but after a couple hours it wasn't too bad

westward10 · Sep 15, 2022

As @UNG says BICC would produce it in any colour provided the quantity was cost effective.
I was also told 'Megger' every gland you make off. Strangely enough was in one of our local churches yesterday and whilst my girlfriend was signing the Queens condolence book I was scratching the MI cables to the light switch thinking they were painted grey but the sheath and shrouds were indeed grey.

7029 dave · Sep 15, 2022

westward10 said:
As @UNG says BICC would produce it in any colour provided the quantity was cost effective.
I was also told 'Megger' every gland you make off. Strangely enough was in one of our local churches yesterday and whilst my girlfriend was signing the Queens condolence book I was scratching the MI cables to the light switch thinking they were painted grey but the sheath and shrouds were indeed grey.

Yup every pot you make off, I always IR the whole coil before installing so I knew it was ok.
Flag out your L with tape after both ends have been IR tested.

UNG · Sep 15, 2022

littlespark said:
I think last time i even touched pyro was running a non-stop 500m length through the bowels of Ninewells hospital in Dundee.

Can't remember the last time I used pyro but I can remember one of the first times as a relatively new apprentice when an electrician and myself had to pull a 7L1.5 fire alarm panel repeater link across one of the Pilkington sites through the maze of underground ducts and cellars the run was about 850m and took us the best part of week to do

Diddy · Sep 15, 2022

Used to love the micc. Well still do but it is a rare beast today. As above test every end as you go. For surface stuff better looking at it than looking for it - Aka leave a good foot when you run micc in if you are doing a large job and wont make the end off anytime soon.
Anyone who tells you that they have never had an end down is simply a liar.
Pro tip lol check each coil quick ir test before running in 100 mtrs of the stuff.....A lot of time surfaced clipped on the add occasion that you come across a internally twisted coil...i have seen this maybe 10 times in 35 years.
The last english heritage sites I worked on (Roehampton) was ALL surface clipped bare micc probably 20 years ago, Don't know if it is the same now but back then EH insisted that all there properties were wired in micc
Finally Micc > FP anything.

Sparky5473 · Sep 15, 2022

Funnily enough I only installed some micc last month, wired staircase lighting in a church tower using white pvc coated and ripped out some rough installed orange coated.

littlespark · Sep 15, 2022

What do you need two different strippers for?

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