Help with damaged underground cables

[GarryB56]

Hi,
I'm looking for some advice.
We are a garden irrigation company and I have an electrical background (up to 16th edition).
We're carrying out an installation in a garden and have damaged 5 armoured cables (one a fibre optic) with our trenching machine.

The cables in question were for a new install to an outbuilding and were not live. They were buried under soil about 75mm with no mechanical protection or yellow warning tape.

The electrical contractor has told the client that he cannot do resin joints as they won't be able to sign off the installation.

Any professional opinions on these points in relation to current regulations would be greatly received as the cost of repair is going to be high
and they're trying to put all the liability on us.

Many Thanks

 

[SagaCU29]

Hi,
I'm looking for some advice.
We are a garden irrigation company and I have an electrical background (up to 16th edition).
We're carrying out an installation in a garden and have damaged 5 armoured cables (one a fibre optic) with our trenching machine.

The cables in question were for a new install to an outbuilding and were not live. They were buried under soil about 75mm with no mechanical protection or yellow warning tape.

The electrical contractor has told the client that he cannot do resin joints as they won't be able to sign off the installation.

Any professional opinions on these points in relation to current regulations would be greatly received as the cost of repair is going to be high
and they're trying to put all the liability on us.

Many Thanks

I would let your insurance deal with it.

 

[plugsandsparks]

Thats really bad luck. Were you informed there were cables in the garden ? - Could it have been reasoned that cables could be there, e.g. direct connection between 2 buildings. A metal detector may have picked these up but its a guess. Direct burial to 75mm is high risk , there is no specific "law" it is based on risk, typically we tend to bury minimum of 500mm for cables carrying power, goes up to 1000mm on farm land.
Resin joints would be the standard repair but the fibre may have to be replaced. of course a duct would have helped here but it really depends what was specified by the client and the original risk assessment done to bury them at 75mm. If the client took that risk, then they reap the reward.........

 

[littlespark]

If the cables were for a new install, then someone should have known they were there, and whoever put them in should have buried them at the appropriate depth, with warning tape.

A CAT wouldn’t have picked them up with no power connected, but I don’t see how anyone can point the finger at you.

 

[marconi]

I am no specialist in liability but if you look at this:

TLC Electrical Supplies - https://www.tlc-direct.co.uk/Book/7.13.3.htm

and see what ’good practice’ looks like and then add in the requirement to record such underground cable runs for future reference a case might be made that you are not wholly responsible and thence liable for the damage to the cables in question. The cable contractor has not done as much as reasonably practicable to safeguard the cables and addressed adequately the risk that they could be damaged during their life by digging or piling and the associated grave risk to humans doing such digging etcetera…..It is most fortunate they were not live because applying the electricity at work regulations and H &S laws would put the cable contractor under severe scrutiny.

 

[SparkyChick]

The cables in question were for a new install to an outbuilding and were not live. They were buried under soil about 75mm with no mechanical protection or yellow warning tape.

The electrical contractor has told the client that he cannot do resin joints as they won't be able to sign off the installation.

Any professional opinions on these points in relation to current regulations would be greatly received as the cost of repair is going to be high
and they're trying to put all the liability on us.

Many Thanks

The point I wish to address is their statement about not being able to do resin joints... unless I'm much mistaken, there is absolutely nothing in the regulations that would prevent them from signing off a cable with a resin joint in it. If they are adamant this is the case, ask them which regulation this would contravene and how it would contravene it. If they cannot provide a valid regulation (we can check it) then they are quite frankly talking garbage.

 

[pc1966]

Fibre repairs are possible but a very specialised job. If they were in duct then pulling a new one through would be the easiest/cheapest option I suspect (even if duct severed you can patch that). Otherwise if they were directly buried then I think there are companies who could do the equivalent of a resin joint repair for fibre, but cost trade off would need to be considered.

Without any warning given (but person who engaged you, or due care with tape and depth by installer) I would be arguing it is not my problem!

 

[littlespark]

OP, can you keep us advised of developments, as most of us are of the impression that whoever buried the cables are the ones responsible.
Ie, not deep enough, not marked on drawings etc.
someone in planning this work must have known you would be digging holes where cables were recently buried.

Are you right in saying 75mm? That’s only 3 inches.

 

[7029 dave]

75mm that is shallow, hardly surprising that they got damaged.

 

[marconi]

I may be transgressing a forum protocol so sorry and forgive me in advance - but I think freddo might have some useful advice.

 

[Robson689]

75mm is very shallow almost sounds like a temporary depth especially with it not being live

 

[JD6400]

I would say that they have no excuse to leave them so shallow and are having a laugh with the no resin stance .
But you have no excuse if carrying out ground works without cat scanning first , especially chain trenching . Sticking it on radio would have found these , to be honest I trust the radio feature more than power detection !
What depth were you trenching at ? Would you have gone through them anyway , even if they had been buried at a respectable depth .

 

[littlespark]

I would say that they have no excuse to leave them so shallow and are having a laugh with the no resin stance .
But you have no excuse if carrying out ground works without cat scanning first , especially chain trenching . Sticking it on radio would have found these , to be honest I trust the radio feature more than power detection !
What depth were you trenching at ? Would you have gone through them anyway , even if they had been buried at a respectable depth .

This is on the assumption that someone has informed him that there are cables there at all. If so, then, yes... he could have used the pulse tone feature of a CAT scan, but he would need to know where the cables were to access them to connect the pulse.
Just a regular CAT scan might have brought them up, but no power would mean it would just be shown as metal in the ground.

 

[pc1966]

As an aside, the Openreach engineers I was chatting to recently were moaning about the fibres they use being totally non-metallic (no SWA) so they cant be traced/found using any Cable Avoidance Tools.

When you wrote "CAT scan" my first thought was WTF do you need Computed Axial Tomography for?

 

[littlespark]

The number of times ive had to explain that a "cable avoidance tool" is not to be used to "find" cables.....

If you want to actually find a cable, then the best thing is indeed, an item of large plant equipment. Never fails.