Depth of 11Kv cable

[sonicm1etn]

Hiya,

Just an answer to a simple question?

Our power went off the other day, while out for a walk I found the reason......

Doesn't seem very deep for an 11Kv cable, especially near the pole. I know it is not finished yet, but do the DNO put protection over the top or leave as is and bury?

Untitled

• sonicm1etn
• 8 Feb 2010
• 1

Untitled

• sonicm1etn
• 8 Feb 2010
• 2

Untitled

• sonicm1etn
• 8 Feb 2010
• 1

 

[securespark]

If my DNO are anything to go by, they do as they please.

They repaired a cable outside our house in the road, and left the joint just under the concrete flags at the very edge of the road, next to the kerbstone. IE not buried at all.....

 

[Guitarguy]

From the looks of it, it's looks a bit shallow as it goes up to the pole, but i can't really tell from the pics. 11kv cables should be a minium of 600mm deep IIRC

 

[wotan]

I can't imagine that could be anything other than a tempory repair, could
OP, keep a check on it, and report back?

Wotan

 

[Lectrician]

Looks like a permenent repair to me.

The new red trefoil cable is what is used these days as opposed to the single cable with three cores in it. It is very typical to join UG and run a new cable up the pole if the cable is damaged close by the pole.

 

[wotan]

Looks like a permenent repair to me.

The new red trefoil cable is what is used these days as opposed to the single cable with three cores in it. It is very typical to join UG and run a new cable up the pole if the cable is damaged close by the pole.

Yes but surely as Guitarguy commented, where it leaves the ground to go up the pole, it looks very exposed, I would hope they would give it more protection.
By the way that is not trefoil cable, it's three seperate conductors, cable tied together, look closely.

Wotan

 

[shaun7r]

That joint is a definate permanent repair and are typically buried at least the best part of a meter. The cables once repaired "SHOULD" be covers with sand to prevent damage, then a layer of really thick plastic tiles to identify the cable if dug up and this also offers a good degree of protection to the cables below.

Where the cable runs up the terminal pole it will run inside a thick plastic capping which should go from under ground level to approx 7/8 feet (out of reach of a tall person)!

Hope this helps!

 

[TicklyT]

Is it still a 'work in progress'?

There seem to be some clay tiles that protected the cable lying around from the excavation - It looks like the joint is resting on one.

How deep can you dig near the pole before affecting the stability of the pole?

 

[sonicm1etn]

hiya,

Thanks for the replys.

I think it is a permenant repair, but they have not finished it yet by covering it yet. I suppose they leave it uncovered for a while to make sure the joint is fixed OK.
I reckon it is about a meter deep, just for some reason I thought it would have been deeper.......farmer and assosciated equipment sprang to mind.

I didn't see any stone slabs near by, but they might have been under the pile of dirt.

If I get a chance I'll wander back up the lane and see if has been filled in.

Thanks again
Dan

 

[GaryMo]

By the way that is not trefoil cable, it's three seperate conductors, cable tied together, look closely.

Have the conductors just been separated for jointing and cable tied back together for neatness?

 

[Guitarguy]

The cables are 3x single core polymeric (probs 500mm stranded copper). I think they have just not laid enough cable to accommodate the lack of depth at. the pole.

 

[shaun7r]

Its my job to build and replace these pole terminations and from the pictures it all looks pretty uniform. As for the cable still being exposed, if that cable is live it should be buried. The cable should be blinded with sand or ground with tiles on top to shield and protect it as soon as the joint has been done. It shouldn't be left exposed in a live condition.

How long ago was the work done? and is it still exposed?

Also the reason that cable doesn't go straight down the pole to a meters depth then come off at a 90 degree angle to the joint, its a solid plastic cable with a large diameter copper core, which is near impossible to bend.

 

[Guitarguy]

Single core 11kv cable like that doesn't get used around where I live/work. We use 3 core polymeric cable and that isn't easy to bend but you are right, the single core is near impossible due to the copper used rather than the ali in the 3 core.

 

[Chukka63]

a few years back we building 9 bungalows in a field basically and needed to re-route overhead cables under the ground.the finsih ground levels were going to be reduced before the end of the job where the cable would run.when they were digging the trench i told them how much the gorund would be reduced,they dint seem too interested,anyway,at the end of the job the cable was barely 250mm below the ground.the safely tape/marker was laid directly onto the cable and soil replaced.at least if you hit the cable you will know what it is when the wmoke clears becaus eof the warning tape/marker.

 

[efiste2]

We use 185mm Polymeric solid aluminum single core cables to connect to switchgear, then do a trasition joint to 3 core polymeric cables just outside of the substation. Or in the case of switchgear replacement/updating the transition joint will be 3 singles to PILC or PICAS, but as far as our rules go HV should be 600 mm deep and screened by tiles or the new plastic barrier tape. And before energising the joints should at least be sanded over.