Advice please depth of buried cable

[CourtneyDesigns]

Hi all
Can anyone tell me is there a legal requirement to bury exterior armoured cable at a particular depth or is it just a recommendation. I am not an electrician but am in dispute with a company.

Any advice would be appreciated.
Stuart

 

[Guest 004]

700mm should suffice

 

[malcolmsanford]

If you have a BS 7671-2008 regs book then regulation 522.8.10 is the guide to take. The last sentance is

" Buried cables, conduits, and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground"

A rule of thumb is in a garden below one and half spade length or below 500mm and under drives and such under between 500-750 mm.

 

[Electricalserv]

Last on e I did 2feet = 600mm for buried SWA

 

[Guest 004]

You need to take into account the soil thermal resistivity, and the ambient ground temperature

 

[CourtneyDesigns]

Just to explain a little further
We were installing a fence for our client on a barn conversion. We hit a swa cable ( for lighting bollard) that was buried approx 4 inches.They new where the fence was to be situated. They are now trying deduct £400 off the oustanding balance.
Thanks

 

[Electricalserv]

Just to explain a little further
We were installing a fence for our client on a barn conversion. We hit a swa cable ( for lighting bollard) that was buried approx 4 inches.They new where the fence was to be situated. They are now trying deduct £400 off the oustanding balance.
Thanks

The regs (which aren't law) just state a suitable depth. Now your version of a suitable depth and theirs may differ. You should have been made aware where the cable was and you should have had a banksman looking for it when digging. If the distributors buried the cable I.E scottish power.... they just lob them in I've seen some 2 inches deep (really).

It is going to be extremely hard for you to get yourself out of this one....

 

[Guest 004]

There is no law on the depth, only recommendations

 

[CourtneyDesigns]

But surely as they new where the fence was to be installed they should have taken this into consideration when burying the cable for the lighting bollard, or at the very least marked the cable with sand and or tape. (Buried cables, conduits, and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground)

 

[Engineer54]

The normally recognised depth for direct buried and ducted cables is 600mm, This is pretty much the cable manufacturers general recommended cable laying depths. Much more than that and you start encountering de-rating factors for the cable(s)...

Under paved or concreted driveways, where it is unlikely to be disturbed in the foreseeable future, this depth can be reduced to around 450mm. In gardens and the like, it is preferable, if not sensible to run cables in heavy duty conduit or pipe, Which also saves on a hell of a lot of sifting of the back-fill soil to get rid of sharp stones, that can penetrate the outer sheaths of cables.


So Courtney Jones, ...What is the arguement with this company on the burial depths of your cable(s)????

 

[Engineer54]

Haha, ....Just reread your further posts here!! 4'' depth won't conform to any recommendation, there isn't even room to lay a warning tape at that depth. Whatever contractor laid electrical cables at that ridiculous depth, should expect them to be damaged, even by there own work force, ...Total nonsense!!!

 

[Electricalserv]

But surely as they new where the fence was to be installed they should have taken this into consideration when burying the cable for the lighting bollard, or at the very least marked the cable with sand and or tape. (Buried cables, conduits, and ducts shall be at a sufficient depth to avoid being damaged by any reasonably foreseeable disturbance of the ground)

How deep was the cable? When was it buried? At the end of the day there is no set in stone depth a cable must be buried.

If you did not know there was a cable there....

My argument would be (for you)..... Why was I not made aware where the cable was?.....if you knew a cable had been buried there, recently, why was I not provided with the information? and why was there no arrangements made for a banksman to be present. For those reasons the disturbance to the cable falls liable to your company for not informing us of its presence and also for not providing suitable bodies to help with the digging process.

What cable was it etc??? SWA?

Edit now see the 4 inch depth.....

 

[PC Electrics]

Can we take it that 'you' are fencers? You were given plans for where a fence should be erected, yes?

Did those plans (or any other information) give warning of any buried cables?

Was this cable newly installed or has it been there years (you haven't really told us much about the background to the work).

Assuming yes, yes, no and new:

i think you are being stitched up on 2 counts:
1. How could you possibly know there was a cable there? If it was running across open ground then 'guidance' would suggest it should have been deeper. Regulation 522.8.10 would also require warning tape. You infer there was none.
2. you are being charged £400 for a £150 (max) job. if this was SWA cable (3 core?) then a proprietory underground joint kit would be about £15. if it was an emergency job and the spark had to go to a wholesaler and back, then you could reasonably expect to be charged half a day.

 

[PC Electrics]

If the cable was recently installed and you were not warned of its presence, then presumably you hit a live cable? Lucky your digger wasn't electrocuted or suffer a shock. Those three dread words come to mind (for your benefit): Health and Safety. Throw that at them.

 

[CourtneyDesigns]

we were sent this computer generated picture and asked to replicate this fencing,which we did. It was not a large job so posts were dug by hand.We werenot informed of situation of cables but we could see the lighting bollards. I feel that as the knew the plans of where the fencing would be installed they should have buried the swa cable much deeper.

 

[PC Electrics]

That pic shows fence posts situated about 6 inches away from lighting bollards, which you say were already there. That puts a different complexion on things. Maybe the cable could or should have been deeper and it defo should have had warning tape, but if you're digging holes right next to lights, surely you ought to have been more careful?

I think you should cough up, but open negotiations about how much. Ask to see the repair bill and pay that amount only.

 

[Engineer54]

How would you know the route/direction of any cable whether there are bollard there or not?? As PC states all this would cost to repair is the price of a proprietary joint.

But really speaking i wouldn't be paying anything, those cables are clearly not complying to any safe depth recommendation. At 4'' ...it won't be too long before those cables break the surface thru the loose earth settling...

 

[CourtneyDesigns]

I dont disagree, we were very careful near the bollard but we hit the cable approx 6feet away from the bollard

 

[Electricalserv]

I dont disagree, we were very careful near the bollard but we hit the cable approx 6feet away from the bollard

The argument of cable depth and warning notices over them is in your favour.

A man digging even if being carefully would have a hard time spotting SWA without any pre warning I.e electrical warning tape!

 

[PC Electrics]

In that case at the very least there should have been warning tape.

Was the cable live when you hit it?
Were you given any advice about the presence of cables and how or where to isolate?
Did anyone check that safe isolation had been carried out to allow you to dig safely?
Did you ask the client about any of these things once you knew lights and cables were present?
What type of cable did you hit and was it buried direct in the ground?

 

[PC Electrics]

Also how extensively damaged was the cable?

 

[CourtneyDesigns]

The cable was live when we hit it, we only damaged the plastic coating. We asked for the cable to be checked and that everything was still working and it for it to be isolated. Everything worked fine and they taped the plastic coating . We were not given any advice on cable pressence. We assumed (wrongly) that cable depths would be suffcient ,allowing safe installation of said fence..This happened in November it wasnt until we had been chasing payment for some time that they mentioned a problem with the lighting bollard and that it was going to cost us £400.

 

[madmac]

The problem is this.......Did the company employ you or are you a sub-contractor because this is the route they will take if you mention Health & Safety to them. If you were responsible for the excavation works by your employees then you would be responsible for interpreting the drawings, using CAT scanning equipment and having a nominated stand by man to oversee the works also a full risk assessment and method statement and perhaps an extra excavation permit issued! Otherwise they should have provided all this as your direct employer and provided a "duty of care" to you and your fellow workers.

 

[Engineer54]

The argument of cable depth and warning notices over them is in your favour.

A man digging even if being carefully would have a hard time spotting SWA without any pre warning I.e electrical warning tape!

Agree.....

You probably hit that cable with the first trust of the fork or shovel. As has been clearly stated here now, 4'' meets NO cable burial depth recommendation. Therefore the cable does not conform as being properly installed full stop!!!
The cables are at an ''unsafe'' depth, and will be prone to ongoing damage, they can also be considered as a safety hazard...

 

[Des 56]

The cable seems to have been an accident waiting to happen

You were given no plans of routing of underground services
You were not warned of the danger
The cable ought to have been at least 2 spades depth
There was no marking tape
The accident was surely very possible and in my opinion not of your making
Are vehicles etc in use over these cables?

 

[Apollo]

So your getting charged £400 for a bit of tape????

They don't stand a chance really unless there is something your omitting to tell us.

Depth of cable and the fact it had no warning tape are your saving grace, throw that at them and see what they come back with!!!!

 

[PC Electrics]

Assuming we're talking about armour cable here and all you did was nick the outer sheath, then a repair with several layers of self amalgamating tape would have been quite sufficient (though I'd probably have put a layer of waterproof duck tape onto the repair first to ensure a sound seal). Maximum cost of repair £50.

I dare say that if this client were playing fair and only deducting £50 or so, then you'd probably have taken it on the chin.

ATEOTD you're going to have to decide how good a client these people are. If not, then argue the ---- with them. If they are and you want to keep their business, make them a reasonable offer, but next time go to town on the paperwork as Madmac says above (and make sure it's included in the price).

 

[CourtneyDesigns]

Apollo
When we hit the cable we notified the site manager whom had it checked and taped, some 3 months later they are saying that 'maybe' damp got into it so it had to be replaced. Im not omitting any thing. A breakdown of their cost- excavate and locate cable £60.00 ,electrician time to locate problem £54.00,5m of 10mm cable £15.00,repair damaged cable £180,reinstating block paving and reinstating cable £65.00 plus VAT. My view is they are trying it on

 

[Guest 004]

'taped' seems to be a key word here
Just throw some regs at him
433.1.4
522.8.10
523.3
708.521.1.1
'Underground cables shall be buried at a depth of at least 0.6 m'

 

[Engineer54]

Apollo
When we hit the cable we notified the site manager whom had it checked and taped, some 3 months later they are saying that 'maybe' damp got into it so it had to be replaced. Im not omitting any thing. A breakdown of their cost- excavate and locate cable £60.00 ,electrician time to locate problem £54.00,5m of 10mm cable £15.00,repair damaged cable £180,reinstating block paving and reinstating cable £65.00 plus VAT. My view is they are trying it on

They are indeed!! Tell them to go after the electrical company that installed these cables in the first place!! They can also take a fair wedge of the blame too, as their on site manager must have observed these cables being laid at the time of installation too!!!