New Electricity Supply: trench specification, and sealing

[ToughButterCup]

ENWL (our Network Operator)  is coming next week to make the connection, and I thought it would be useful to go into some detail about establishing the supply connection in terms of what a self builder needs to do before fitting a Consumer Panel. I also have a couple of questions.

 

I have already done all the paperwork necessary, and paid the fee. There have been two pre-inspections on site: but things have been a bit fraught recently, so I'm running behind schedule. I need to dig the trench this week. My principal concern is to  do it once and do it right.

 

I need to dig the trench over our land to meet up with the incoming trench from across the road.

 How deep should it be?

 

ENWL used to provide a guide for making connections, but, as is often the case, large organisations  don't maintain their hyperlinks, and so the  hyperlink is dead. However, I found the correct one here. (accessed November 2017) Quite why such a document should be found on this type of online resource ( but not the DNO's site) baffles me. The document may well be out of date.

 

The DNO guidance says (on footpaths or verges)  that low voltage cable should be 450mm from the surface. But that crossing  a road, it should be 600mm below the surface, So, I need to dig a trench 450mm deep plus 150mm (the low voltage cable diameter), but the cable across the road is 600mm below the surface (plus the diameter of their ducting)

 

So there's a mismatch.  I only need 3 meters of ducting across my land. (it's less than that from the road to our piggery - where the meter box will be)

 

[PeterW]

Go for 450 and stick a duct in it - warning tape over the top and job done. 

 

 

[Onoff]

Erm...current info on their site:

 

https://www.enwl.co.uk/get-connected/new-connection/1-4-properties-or-single-connections-up-to-60kva/pay--plan2/

[MikeSharp01]

1 hour ago, PeterW said:

warning tape over the top and job done. 

Back fill a 100-150mm before taping or tape twice, once directly on the duct and once 100-150mm up, so you, the next person anyway, get some prewarning of the duct below. Shows this on the stuff @Onoff has pointed you at.

 

 

Edited November 13, 2017 by MikeSharp01

[Onoff]

If they're digging 600mm deep then gradually slope your trench near the road to meet theirs.

[ToughButterCup]

The issue is the depth mismatch. Got through to the right person late this afternoon; and she said to taper the trench. So that's what I started to do. Until I found the end of the hockey stick.... 800 mm down. ?

I'm not getting used to doing stuff for the first time anything like fast enough.

Need a break I think. 

[ProDave]

I think the depths are a minimum. I have never known a DNO refuse a connection because the trench is too deep. They WILL refuse a connection (as I have seen) if the "duct" you leave for them is a bit of blue water pipe.

[curlewhouse]

As regards the warning tape - check they do accept the normal warning tape - Northern Power Grid for example don't allow the normal polythene tapes use and insist on "tile", basically a hard plastic version of the tape, (which when you try and buy some you find is available only in 40m lengths (around £50)... for my 2 metre long trench! - so in my case, scrounged FOC from some NPG guys I saw working on a site elsewhere).  They also would only accept "non coilable" ducting (despite the national DNO web site showing an example of coiled ducting and saying it is suitable). Everywhere else on our site after the meter is just the normal polythene stuff of course.   

  

[Onoff]

1 hour ago, recoveringacademic said:

The issue is the depth mismatch. Got through to the right person late this afternoon; and she said to taper the trench. So that's what I started to do. Until I found the end of the hockey stick.... 800 mm down. ?

I'm not getting used to doing stuff for the first time anything like fast enough.

Need a break I think. 

 

How long is your trench?#

 

Didn't read your first post properly (man flu starting)! If you want some yellow warning tape pm me your address and the length req'd.

Edited November 13, 2017 by Onoff

[nod]

9 hours ago, recoveringacademic said:

ENWL (our Network Operator)  is coming next week to make the connection, and I thought it would be useful to go into some detail about establishing the supply connection in terms of what a self builder needs to do before fitting a Consumer Panel. I also have a couple of questions.

 

I have already done all the paperwork necessary, and paid the fee. There have been two pre-inspections on site: but things have been a bit fraught recently, so I'm running behind schedule. I need to dig the trench this week. My principal concern is to  do it once and do it right.

 

I need to dig the trench over our land to meet up with the incoming trench from across the road.

 How deep should it be?

 

ENWL used to provide a guide for making connections, but, as is often the case, large organisations  don't maintain their hyperlinks, and so the  hyperlink is dead. However, I found the correct one here. (accessed November 2017) Quite why such a document should be found on this type of online resource ( but not the DNO's site) baffles me. The document may well be out of date.

 

The DNO guidance says (on footpaths or verges)  that low voltage cable should be 450mm from the surface. But that crossing  a road, it should be 600mm below the surface, So, I need to dig a trench 450mm deep plus 150mm (the low voltage cable diameter), but the cable across the road is 600mm below the surface (plus the diameter of their ducting)

 

So there's a mismatch.  I only need 3 meters of ducting across my land. (it's less than that from the road to our piggery - where the meter box will be)

 

Hi Ian

 

we had a simalar delemer 

the chap who came for the survey said 450 should be ok So I did it 600 just in case I lined the bottom of the trench with pea gravel

and laid the red solid electrical ducting

Taped it and filled it in just leaving 2 mtrs from the box exposed

 

i have a full roll of electrical ducting tape that you can have 

and perhaps ten mtrs of mains ducting Would have to check how much is on the coil

both surplus to requirement 

 

Also a roll of water mains tape

   Gary