Paper insulated incomer falling apart

[John D v2.0]

Is this a problem? Cutout replaced less than 2 years ago, I was just under the stairs and just noticed it's pulling apart now. It's a 3 phase if that makes a difference

 

[ban-all-sheds]

What's melting? The cable sheath, or the PVC "insulating" tape wrapped around it?

 

[John D v2.0]

I don't think anything is melting, it seems like the lead is wrapped in a spiral with bitumen or something on the outside, and is pulling apart.
There are no heavy loads so it shouldn't be overheating.

 

[bernardgreen]

There are no heavy loads so it shouldn't be overheating.

Heat is created when there is resistance to the flow of current. If there is a poor connection then current as low as 1 amp can create enough heat to ignite material.

 

[John D v2.0]

Indeed, hence why I said shouldn't rather then can't. From inspection it seems to be pulling apart rather than melting. Here's a slightly different angle.

 

[securespark]

I'm not sure there is anything to worry about.

There appears to be a few strands of bitumen-soaked fabric escaping from around the tape.

The tape will be covering a spring coil wrapped around the lead sheath under which is trapped the earth braid.

I do wonder why there seems to be a cable running up behind the cutout, though.

If you are worried about the cutout, you could ring the DNO.

 

[John D v2.0]

Thanks secure spark,
Actually it's hard to see on the photos, but it's the spring coil that's coming apart, but if that's not a crucial part then it's less worrying.
The t&e goes behind the meter board to the cu that's above, I think that is the boiler one. They mounted the cutout hanging off the bottom of the board because they had to shorten the cable to change the cutout but the new board needed to be high enough for the tails.
I've sent the photo to the dno so we'll see if they're worried at all!

 

[ban-all-sheds]

it's the spring coil that's coming apart, but if that's not a crucial part then it's less worrying.

If it's what connects your main earth cable to the supply earth, it's probably reasonably crucial.

 

[securespark]

Agreed!

 

[John D v2.0]

I thought secure spark said there was an earth braid under the lead? Or does that symptom mean the braid has snapped off?
The band itself hasn't actually snapped, just the spiral has spread out.
Anyway I'll check the earth loop at the intake later and if it's fine I'll wait and see what the dno comes back on the existing ticket. If it's >0.8 I'll raise it as a missing earth.

 

[John D v2.0]

Oh sorry I suddenly realised the earth braid is the connection from the met to the cable, and the spring coil is the thing that holds it on the cable. I should work out the buildup of that cable, I guess is paper insulated steel band and it's the band coming apart but the lead is the earthing conductor?

 

[John D v2.0]

Basically to rewind the whole thread to the beginning, there's some part of the cable that's wrapped in a spiral along the whole length. That spiral is pulling apart near the end. Is that likely to be dangerous/a problem

 

[Adam_151]

Looks fine to me, the spiral spring is only at the end by the way.

What you haves is the cores insulated in oil impregnated paper, this is contained in a lead sheath that provides the earth, over this (because lead is soft) is steel armouring tape which is wrapped around the cable to give it mechanical protection, over this is bitumin coated fabric to protect against corrosion. The earth braid is attached by stripping the cable back to the lead sheath and putting a sprialed spring on which holds tightly to the lead, under this is trapped the earth braid, this is then taped over with pvc tape. I have known instances where the briad and spring have ended up onto the armour (lazy jointer, possibly?) rather than the sheath, this usually results in a high earth loop. Traditionally you would have not had the spring, the earth (which might have been a few bar strands) would have been sweated (soldered) straight onto the lead, but they don't tend to do it that way anymore

The fabric just looks a little frayed where they stripped it, and perhaps didn't do a perfect job with the tape

 

[Adam_151]

http://solutions.3m.co.uk/wps/porta...fVxMDIycXL1cnE18DCyMzPWDU_Pi3Z30C7IdFQEl6q1h/

 

[John D v2.0]

Thanks Adam that makes sense, so I needn't worry about the wrapping as long as the lead is good.
When they did the work the impedence was about .25 ohm so I'll compare with that later.