Incoming Power cable - How much movement is possible underground (Ed.)

[padstar]

Hi,

Firstly merry Christmas to everyone. I hope you had a good few days rest.

I am installing electronically retractable bollards in my drive before I have the resin bound gravel finish laid.

I dug the hole for the 1st bollard today which I knew had the mains power running nearby. Typically over a 6m wide opening the mains power sits within the 300mm space i needed it not to and 100mm above where I needed it to.. As it stands it will hit the bollard casing by approx. 100mm. Images show where the center line of the 300mm casing will sit and the 2nd image shows where the cable would need to be moved to to miss the casing. The case is cylindrical so the pinch point is at approximately 200mm in. The length of exposed cable is approximately 600mm.

How much persuasion can these cables take? Light ran out before i could safely investigate further but can a cable like this be "nudged" over 100mm?

I realize what this is and have seen 1st hand the consequences of compromising a cable like this so am very mindful that the correct answer is "you should not touch" but in reality is using something to persuade it over 4" a huge risk? I assume UKPN will not be interested in such a job or will charge an arm and a leg for it.

What do people normally do in this very unfortunate by typical luck situation?

If I remove more earth at either end will it give a little more?

NB. The casing encloses all moving parts so there will be nothing "mechanical" coming into contact with the cable.

 

[23vc]

What would be involved in reworking things above ground to allow for the bollard to sit in a different position? Whenever I’ve encountered underground mains they don’t feel like they’d budge at all.

 

[padstar]

It would require introducing a 3rd bollard which would be a final resort and one i want to avoid if at all possible

 

[Murdochcat]

There will be very little movement in that cable AND remember damaging it isn’t a great idea, penetrate it with something conductive and all you’ll need is a wooden box - for you

 

[23vc]

I think it’s a no go. No matter how much you dig it out it’s only going to move if there’s a load of slack in it, which I can’t imagine there being. And it’d have to be a hell of a lot of slack to move a section of it 100mm. Otherwise, unless the whole thing moves including the entry point to the house, it ain’t going to budge

 

[padstar]

Ok. Sounds like i need another measure up in the light to see if I can get away with making it work by squeezing it in next to the cable. We are talking less than 100mm so I will have to try and make it work another way.

Thanks everyone

 

[RrogerD]

Are you a builder by trade? If so then you'll likely know the correct answer.
If you're simply a 'have-a-go' DIYer then I think your best bet is to speak to the Electricty board for your area. You're playing with fire there plus, they're going to be pretty miffed if you mess up their supply (it's their property all the way to the main fuse inside the house).
Best bet, move your bollards.

 

[^woody^]

Shorter bollards?

 

[JohnD]

If a bollard is in the raised position when it is struck by a vehicle, I can imagine its root might disturb the ground in a one-metre diameter crater.

 

[bernardgreen]

A

(it's their property all the way to the main fuse inside the house).

And in the other direction all the way to the 200 ( or maybe 400 ) amp slow blow fuse in the substation. 46kW in the ground when the cable is damaged ( or 92kW ) until the slow blow fuse ruptures,

 

[flameport]

How much persuasion can these cables take?

None.

If you want to install bollards or anything else there, that cable will need to be removed and a new one installed elsewhere.
The perfect time to do that is before an expensive new driveway is installed.

If you go ahead and install items near to that and it's later damaged, you will be paying for the cable replacement anyway, plus another driveway.

 

[23vc]

If a bollard is in the raised position when it is struck by a vehicle, I can imagine its root might disturb the ground in a one-metre diameter crater.

Pretty effective deterrent tho, when it slices the mains…

 

[padstar]

This is going from bad to worse.

Had another look this morning and the bollard will go in beside the cable with no movement required (comments regarding the bollard being struck are noted).

I then cracked on with digging the hole for the 2nd bollard. Almost done and I hit something in the final 200mm. Ohh yes its a 2nd what looks like power cable. I mean you just couldn't make this up!

I ASSUME 1 is the current live feed and the 2nd is an old now redundant feed. Unless the 2nd is taking some crazy route to another property then this is all I can see as being the case.

Will UKPN come out and verify which is live and remove/cap the redundant (if that is the case). Surely they have some responsibility to mark or remove.

Neither cable is taped so God knows which is the newer one. It looks like the one in the 1st hole purely on condition of the cable.

Are UKPN quick to respond and what would I be looking at to move a cable if required? Would I have to pay to remove a redundant cable?

 

[23vc]

Can you not get a telescopic type bollard which doesn’t need as much depth? Even if they cost more, still cheaper than getting cables shifted

 

[padstar]

In hind sight I should have dug the holes before purchasing the bollards but i did not expect to be this unlucky, but they are here now and were not cheap so I am in an awkward position.

The automatic bollards seem to require a silly depth. 900mm for a 500mm bollard.

If the 2nd is a dead cable then surely the cost to cap it cant be ridiculous especially as I have the hole dug.