Damage to armoured cable - repair ?

[Rick Hughes]

I have 3 core SWA armoured cables under my drive, and then popping up and entering the base of my entrance pillars - providing feeds to lights. These were buried deep, pea gravel & warning tapes .. Etc.

While my drive was being prepared for paviors - I pointed out several times to contractors where they would be, and while deep across drive do not dig within 4" of base of pillar - I'd do that by hand. I cleaned around to show where they come vertically up and then enter pillars . today when deciding to scrape around the borders ready for start of edging they ignored all . and have now taken a small chunk out of the top of the pvc sheath exposing the armour wires on one cable. aprox 5mm wide x 10mm long, exposing armour wires in centre of damage.

I know ideally cables should have entered through foundations rather than across first brick course - but it is where it is.

I am not relying on the armour wires for earth .. so no worries there, but anybody know a practical way of repair ? The contractors say simply to ignore - as long as not cut through there is no problem . !

Next week it will be under the pavior drive so not exposed .. but would prefer to prevent water entry and possible future problems. Options ?

- multiple layers of pvc tape ?

- Is there any liquid resin I can pour over the whole cable to encase the damage?

- Self-Amalgamating tape?

- In case in concrete ?

- or should I just ignore as contractors advise.

The damage is within 10mm of the wall, and unless I want to demolish the pillar . I can't get the cable out .. I can probably pull it back 50 mm or so effect a repair, but not enough room to cut & joint. No point in suggesting I ask them to put it right, they would just bury and continue.

[Cicero]

================================== You could wrap it with hessian pipe lagging impregnated (by painting) with Bitumastic paint. An offcut of damp proof membrane might also work in a similar way.

Cic.

[Harry Bloomfield]

Rick Hughes submitted this idea :

Left as is it will corrode and rust through given enough time - so it needs some protection. You can buy two part resin 3M joints - flimsy plastic former, complete with the resin, but probably this is more than is needed. If the damage is slight, defintately no internal damage - I would be inclined to suggest warming the cable and pouring in some two part resin (Araldite) then adding some self amalg tape over the top once it has set.

[TMC]

Butyl mastic tape

Tony

[RW]

Get the contractors to repair it....it's their f*ck up

[Dave Liquorice]

So not a large area of exposed armour? If you can get at it to wrap self amalgamting tape around it that is what I would do. Extending a couple of inches beyound the end of the damaged insulation and several layers thick over the damage, done in a spiral one way then backdown, back up and back down again at least. I might be tempted to but some form of harder protection over the top of the SA tape.

[Steve Firth]

`they have damaged the cable, they are responsible for making good. Either withhold enough money from their payment to cover the cost of replacement or make them put it right.

Do not be fobbed off by them as you seem to have been so far.

[<me9]

Just to be on the safe side a layer of denso on top will add a further flexible layer of waterproofing.

[Andy Hall]

I don't think that bodges with tape are the right way to address this. They are not a good long term solution against water ingress which is a problem since you are losing access.

I had a similar issue to this. The damage is slight, so it really isn't worth making the contractor replace the whole cable run or even replacing a section, which would reduce reliability as well.

Therefore a good solution is a resin joint kit. This is what would be used if a section of cable were added in anyway.

TLC and others have these at about £20 each e.g.

is no need to break into the cable, just to clean it up. Then carefully cut the ends of the shells to match the cable diameter and clip on the shells with the damaged area in the centre. Mix the two part resin supplied and pour carefully into the hole in the centre of the shell. The resin becomes reassuringly warm during curing and will probably ooze slightly from the ends.

This is a more expensive solution than bodges with tape, but I am quite sure that the contractor will be more than happy to pay for it.

[The Natural Philosopher]

Ah well. I cut the PVC on muine whje laying it. Main feed from te substaion..

I taped it up with PVC. Now of course a problem DID show up when the house was rebuilt, and I assumed that was it. However it wasn't. The foundation digger had cut through the armour as well. In a completelt different place.

My bodge is still fine after ten years.

So essentially I think its probably fine.

I would do that.

Just tape it up to prevent water rotting the armour.

[John Rumm]

I assume you can't slide some adhesive lined heat shrink over the damaged section? That would be my first choice. Self amalgamating tape would probably be my second...

[Mike Barnes]

Is that going to work?

[Rick Hughes]

Not been fobbed off, but they are pavior layers .... and any repair they do is going to be what they think is right ... and bearing in mind they feel it needs no repair at all, to be sure of getting it done right, I'll do it myself.

Rick

[Rick Hughes]

I did think of those, I used to joint up to 500mm2 cable with the big brother versions.

The problem may be physical size of the case.

The cable come out of wall, then turns 90 degrees down .. the damage is right on the point where it takes the 90 degree downward bend. Repair would have to be exactly on the 90 degree bend.

Maybe if I could find a way of using the jointing compound without the case ...some thought needed.

[Rick Hughes]

good thought - I have some denso tape

[Rick Hughes]

wish I could .... the armoured cable is terminated within the pillar which means I can't withdraw the cable to slide on a sleeve - 'twas my first thought.

I suppose what would be ideal is some form or heatshrink tape .... but never come across any of that.

Maybe I will have to bite the bullet and take off the copings from top of the pillar, and undo terminations to allow me to use a sleeve.

Can you buy short lengths of adhesive lined sleeve - what I have is too large a diameter ?

Rick

[dmc]

Split it lengthways and wrap it around the damage like tape? Might need to glue the ends somehow I guess...

[Dave Plowman (News)]

If access is ok I'd clean it thoroughly and make sure it's dry - use a hairdrier etc. Then cover the exposed part in ordinary silicone sealer, wiping to the shape of the cable, and leave to dry. Then a few layers of gaffer tape with cable ties at each end to prevent any possibility of it unwrapping.

[John]

If you see any BT (suppose it's now Openreach) cable jointers knocking around, try to blag a heat-shrink closure from them. I can't remember the proper name 'cos it's been a while since I worked there but basically it's a sheet of heat-shrink material that can be wrapped around the cable and has a type of zipper closure on top. I reckon it would cope with the bend no problem.

John

[Peter Parry]

You can get heatshrink tape with a layer of hotmelt adhesive

Self amalgamating tape though is more than adequate for the sealing but isn't resistant against abrasion.

Using self amalgamating tape and then some spiralwrap of the appropriate diameter you will end up with a waterproof and physically protected join without too much bulk.

Spiralwrap comes in 5, 10 or 20mm diameter - eg