Trying to identify type of external cable

[Little Plumb]

Got an external junction box on an outside wall that feeds 2 external spotlights.

The cable that feeds the power into the box is of a type I've not seen before.

It's plastic coated over what appears to be a hollow copper core.
This goes into the box where it then goes into a cylindrical shaped object that looks a bit like a capacitor. There are 2 wires coming out of the top of this "capacitor" which feed the wire going to the spotlights . The live has become disconnected from the "capacitor"leaving a small hole in the top of the capacitor.

There doesn't appear to be anyway to re-fix this wire so I'm a bit stumped as to what this cylindrical shaped object is and how I can reconnect the wire,

The power is fed via a remote dusk till dawn light sensor.

Any advice welcome.

 

[securespark]

Need pictures, really.

Take digi images then upload them to PhotoBucket (or similar), posting the URL here.

 

[Steve]

it SOUNDS LIKE MICC - mineral insulated cable. I would advise you get an electrician to sort this out. That "capacitor" is actually a "pot", which is meant to be watertight - once the seal is broken, moisture will get into the mineral in the cable and ruin its insulating properties.

Is this an ex-council house?

 

[Little Plumb]

try again

 

[securespark]

Yeah, crafty's right. That's MICC, and it looks like it's been under stress.

It needs specialist attention & tools to repair.

 

[Lectrician]

Good god.

Thats not a DIY repair!

It needs re-potting, glanding, and terminated correctly into a suitable enclosure!

 

[ninebob]

Furthermore, I don't like the outside use of ordinary T&E between the JB and the lights.

 

[Little Plumb]

well that's how I found it, will get an electrician to deal with it.

Just out of curiosity why are micc cables used and what's the pot for?

Also what sort of cable should I specify for running upto the lights instead of the twin & earth?

 

[JohnD]

I recognise that picture. It's my exercise ring.

I jump up to it each morning, and swing on the wires to improve my upper-body strength. I've noticed it seems to be getting a bit loose recently.

 

[Adam_151]

When you phone up electricans make sure to ask them if they do pyro/MICC work before getting them to quote, its not used that often these days, especially not in houses, and not all sparkies will have the correct potting tools, etc. This will save you undue hassle

 

[Little Plumb]

found the information on micc here

http://en.wikipedia.org/wiki/Mineral_Insulated_Copper_Clad_cable

god know why it was used on an external lighting circuit.

thanks for all replies

 

[Spark123]

Just out of curiosity why are micc cables used and what's the pot for?

MICC cables are generally used for their fire resistant properties, they can also take a fair impact and as they have a metalic sheath can be used outside the safe zones within walls. The pots are used on the end of the cable to seal them as the magnesium powder used in pyro is very susceptable to damp.

Also what sort of cable should I specify for running upto the lights instead of the twin & earth?

Your eleccy should be able to advise you on this, probably hi-tuf or similar but it really depends on the location and environment.

 

[plugwash]

properly installed MICC (pyro) is about the best cable type there is and was very common for wiring in public areas inside or outside, its tough yet much thinner and therfore in skilled hands much easier to route neatly than steel conduit. and as a bonus virtually fireproof. As the wikipedia article says the pot is needed to seal the end.

having said that the pyro in that pic has been horriblly bent and though there is a pot on it you really couldn't call it a proper termination. I'm guessing that some mods were done by someone who had aquired some pyro gear but didn't really know what they were doing.

if the seal has been damaged and damaged for a while (or was never properly sealed in the first place) the cable may have to be cut back quite some distance before sound insulation is found.

As others have said this isn't a diy job to repair. working with pyro requires special termination tools and an insulation resistance tester is vital (unlike on PVC cable where while sparkies do insulation resistance tests as a precaution they very rarely fail on cable that looks dry and in decent condition)

As for what cable to use, MICC as used already is a very good choice from a longevity point of view but is a bit pricey. Other options include SWA (horribbly bulky) arctic flex (horrible colors) and HI-TUFF flex (probablly the best option if you decide against MICC)

 

[Steve]

anyone else noticed the horrible burning on those terminal blocks?

And i'm assuming (hoping) that there was a cover on this box?

Has something gone wrong with this circuit? I mean, what prompted you to start investigating this now?

 

[Little Plumb]

both lights that are fed from this cable were not working so I looked in the box and found the disconnected wire on the top of the pot.
never having seen that sort of cable before prompted the post.

I couldn't make out if it was actually burnt in there or just dirt.

The 2 lights being fed are a 300w standard pir activated floodlight and a 70w sone floodlight.

All other external lights appear to be working.