Regs on UG cable depth and marking

[Tafia]

Hi,

Some uplighters have been installed at a local church and it seems to me that the UG cables may not have been buried deep enough and also that they have not had a warning tape buried in the ground above them to warn folks not to dig there.


Can anyone confirm what I have found in the Electricians Guide to the Regs, i.e that all ug cables should be buried deep enough to ensure that they are not likely to be damaged during normal use of the ground.

One cable passes from the church wall to the lamp and is buried where folks have been burying ashes of relatives so it is quite possible that sooner or later someone is going to stick a spade down there again. The soil disturbance for the new cable installation is only about 100 mm wide so it seems unlikely that the cable is buried more than a few inches down.

Can anyone advise please.

Thanks.

 

[johnboy6083]

in this case i agree that it has been a case of just whack it in, and nobody will notice. I would get them back to dig a proper trench, with ducting, and marking tape.
Ducting is not required normally, but in this case with people digging, it should be used.

 

[Tafia]

Thanks for you prompt response Johnboy. I was a sparky some years ago and then retired as a supervisor in the polyphase meter test station.

I am now on the local council which asked for the lighting at the church though I missed the last meeting.

Can you say what the regs say about this together with the relevant number. The electricians handbook quotes: 7.13.3 - Underground wiring. Is that correct?

Many thanks again

 

[malcolmsanford]

Reg 522.8.10 is the one that concerns you.

There are dedicated cable depths in the BS 7671-2011 but these concern special locations not churches I'm afraid

 

[jase]

just jumping on the back of this, I am considering putting some lights in my garden just GU10 spike lights, but when it comes to running the armoured i was going to clip it along the toeboards as i dont want to bury it, which wouldve been fine until a couple of weeks ago when the high winds blew some fence panels over so i had second thoughts about clipping it to fence, it would be a right pain in the arse to bury cos the beds are choca bolc full of shrubs and tress etc, Does anyone know of hand if it is acceptable to just have an SWA lying on top of the ground, running along the bottom of the fence but not attatched to it? would eliminate the need for warning tape too as you could physically see it

 

[PC Electrics]

Hold up a moment! Your whole assumption that the job hasn't been done properly appears to hinge on the basis that the trench is "only" 100mm wide !! How do you reach this conclusion?

I have a trenching spade which has a blade just about 4 inches wide at the top and about 14 inches long. It is perfectly possible to dig a deep but narrow trench.

Do you have any other evidence to suggest the job has not been done properly? Have you dug a test hole to see where the cable is?

Seems to me you need some more facts before casting aspertions.

 

[malcolmsanford]

just jumping on the back of this, I am considering putting some lights in my garden just GU10 spike lights, but when it comes to running the armoured i was going to clip it along the toeboards as i dont want to bury it, which wouldve been fine until a couple of weeks ago when the high winds blew some fence panels over so i had second thoughts about clipping it to fence, it would be a right pain in the arse to bury cos the beds are choca bolc full of shrubs and tress etc, Does anyone know of hand if it is acceptable to just have an SWA lying on top of the ground, running along the bottom of the fence but not attatched to it? would eliminate the need for warning tape too as you could physically see it

It's your garden.....................................

I'm sure your not going to have undue stress on the cable or the terminations and as it is SWA and you know it's there your not going to damage it either.

So as said ......................it's your garden

 

[JD6400]

just jumping on the back of this, I am considering putting some lights in my garden just GU10 spike lights, but when it comes to running the armoured i was going to clip it along the toeboards as i dont want to bury it, which wouldve been fine until a couple of weeks ago when the high winds blew some fence panels over so i had second thoughts about clipping it to fence, it would be a right pain in the arse to bury cos the beds are choca bolc full of shrubs and tress etc, Does anyone know of hand if it is acceptable to just have an SWA lying on top of the ground, running along the bottom of the fence but not attatched to it? would eliminate the need for warning tape too as you could physically see it

Hi Jason , if you want give us a ring and i can sort out one of our moles for you to borrow .
I am pretty sure we have no moiling jobs booked in for a week or so at the moment , let us know and i will make sure that there is a set up back at our stores in Gran""""""" .

 

[PC Electrics]

Jase, there is no regulation which requires swa to be buried. Neither is there any regulation forbidding swa to lie on the top of ground. The basic rule with any regulations is that unless it is expressly forbidden then it is allowed. Lay your cable along the base of the fence where it is unlikely to be disturbed but also won't be damaged if the fence comes down again. I'd suggest putting little posts in to mount the terminal boxes on to keep them above ground (and hence out of any water). Or use those super waterproof terminal boxes, can't find a link to them just at the mo

 

[jumpin jax]

a proper trenching machine will also leave only about 4 inches and go to a depth of at least 18 inches but in a graveyard hopefully not as much as 6 feet!

 

[Tafia]

Hold up a moment! Your whole assumption that the job hasn't been done properly appears to hinge on the basis that the trench is "only" 100mm wide !! How do you reach this conclusion?

I have a trenching spade which has a blade just about 4 inches wide at the top and about 14 inches long. It is perfectly possible to dig a deep but narrow trench.

Do you have any other evidence to suggest the job has not been done properly? Have you dug a test hole to see where the cable is?

Seems to me you need some more facts before casting aspertions.

Yes I do intend to dig a little to see what is there. However, the turf has been re-laid neatly and is about 100mm wide, if that. I really doubt that a hole 400 mm deep could dug without touching more of the grass. I too have a trenching shovel and it is wider than the marks in the grass. The job was only done in the last couple of weeks so the line of the cable can be clearly seen.

Another lamp has been wired by the same sparky at the church and the wire crosses a tarmac path. A slot about 2 inches wide has been cut in the tarmac and then fresh tarmac has been laid on top. To dig that deep enough would need a very long spoon. I was not casting aspertions as you suggest, I was asking the question in the name of safety.

Thanks

 

[trev]

If I were you I'd gently dig a couple of test holes and if it turns out that the cable is not deep enough and is not marked get the guy back to do it properly and insist on an inspection before the trench is backfilled. At that time you can discuss the 2 inch trench with him.
It could well turn out that a 100mm trench is deep enough though

 

[Tafia]

Anyone have the wording of of Reg 522.8.10 as mentioned above?

Cheers

T

 

[Tafia]

Reg 522.8.10 is the one that concerns you.

There are dedicated cable depths in the BS 7671-2011 but these concern special locations not churches I'm afraid

Does the stuff listed here


http://www.******************/Book/7.13.3.htm

agree with the 17th edition and with the reg you quote?

Thanks for your patience

T

 

[PC Electrics]

Have you thought about ringing the Sparks and asking him about what he has done? A friendly 2 minute phone call might be all that is required to put your mind at rest!

 

[malcolmsanford]

Regulation 522.8.10

Except where installed in a conduit or duct which provides equivalent protection against mechanical damag, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor. The location of buried cables shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shall be identified. Buried cables, conduits and ducts shall be at a sufficient depth to avoid being damaged by any reasonable foreseeable disturbance of the ground

I've highlighted the relevant points concerning your cable and how it was erected

 

[Tafia]

Regulation 522.8.10

Except where installed in a conduit or duct which provides equivalent protection against mechanical damag, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor. The location of buried cables shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shall be identified. Buried cables, conduits and ducts shall be at a sufficient depth to avoid being damaged by any reasonable foreseeable disturbance of the ground

I've highlighted the relevant points concerning your cable and how it was erected

Many thanks sir, I try to be sure of my facts at council meetings and now, thanks to you, I can quote the relevant regulation. I don't know who the sparky is who has done this work as it was arranged via another councillor.

I will contact him so that, hopefully, it can be resolved without raising it officially at the meeting.

Thanks again for your time and patience.

Best wishes.

T

 

[jase]

Hi Jason , if you want give us a ring and i can sort out one of our moles for you to borrow .
I am pretty sure we have no moiling jobs booked in for a week or so at the moment , let us know and i will make sure that there is a set up back at our stores in Gran""""""" .

Cheers Dave, it's more a theoretical question for the future really, so no real need for it at the mo!!

 

[Engineer54]

Probably all installed by one of the churches odd job man from it's congregation, that's normally the way of things at UK churches!!! Always done on the cheap...lol!!

 

[Octopus]

Regulation 522.8.10

Except where installed in a conduit or duct which provides equivalent protection against mechanical damag, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor. The location of buried cables shall be marked by cable covers or a suitable marking tape. Buried conduits and ducts shall be identified. Buried cables, conduits and ducts shall be at a sufficient depth to avoid being damaged by any reasonable foreseeable disturbance of the ground

I've highlighted the relevant points concerning your cable and how it was erected

The real problem with this regulation is the word "sufficient" - which is open to interpretation. The man who's paid to dig a 600mm hole and put the cable in may decide that 250mm is OK as no one will see it.

The regs, IMHO, should outline specific examples i.e. flowerbed - 600mm,