What do the electricity, gas and water companies require by way of trench depth, separation of ducts, marking etc. for extending and moving services to a fresh location?
I have found on-line suppliers of black duct, yellow pierced duct and marking tapes but little further information.
The run is about 15m from existing supplies which are laid at around 18" deep and about 12" separation with no tape.
In message , Tim Lamb writes
Ah! I hadn't dug very far.
Gas 450mm, water 750mm, electric 600mm
Any further thoughts?
When the gas company replaced the services in my road they dug trenches in the road, but used a mole to run new pipes to each property. The water company's contractor also used a mole to replace the service pipe to my next door neighbour recently. I don't think the gas company likes ducts, as they can pose an explosion risk.
They usually have the info buried deep within their website, often in the ' new connections' section.
Western Power Distribution say
We require a trench which is 530mm deep and 300mm wide along its whole leng th. You can only dig trenches on your own land. The trench bottom should be level and free from any sharp stones or objects which may damage the service cable. Our cables are normally laid directly into the trench so need to be reinsta ted with 75mm of stone dust. In some cases ducting can be laid in advance o f the new supply, and this ducting can be obtained from your local WPD offi ce.
Draw cords should be incorporated and the ends marked for ease of location. Trench depths in pavement or private land shall be 530mm (min. cover over cable 450mm) and in roadway shall be 600mm (min. cover 520mm). Where cables are not protected in duct they must be blinded with 75mm of crushed stone dust and approved yellow ?electric cable? marker tape laid above.
Without charge to WPD the Customer/Developer will, where agreed by prior arrangement, install suitable 38mm internal diameter WPD approved tubing from the service position to the footpath or verge etc. as shown on the pla n. Where an internal meter position is agreed a 500mm slow bend entry should b e installed at the meter position. A draw cord should be incorporated and the end marked for ease of location. There should be a minimum of 520mm cover in th e roadways and 450mm cover in pavements and private land.
Other DNOs vary so you have to check details locally.
Owain
Nonsense. It's because water in the gas mains is a nightmare to sort out.
OK Phil. Somebody should have told the original groundworks contractor:-)
Gas only needs to be that deep if it is unprotected. Under a concrete path you can get away with less.
Water needs to be deep enough not to freeze, so 750mm seems a lot for anywhere south of Northumberland.
Only electricity needs to be below spade depth, but it will be armoured cable anyway.
In about 1985 near East Grinstead in West Sussex, a contractor drove his mole through both medium/high pressure gas and a water main. The water pressure 'won' and people were surprised to see a water feature coming out their gas hob for miles around.
Gas was cut off for miles around, and BG had to visit *every* property and turn off their appliances and then return and purge them. If you were out they just dug up your garden and/or pavement and chopped your supply.
They brought gas engineers in from all over the country and Eire and commandeered the (largish) carpark in one sussex village as their Ops centre sorting the mess out.
See my comment above. I remember it well. Neighbour was an air hostess and she came home to a cold house and a hole in her front garden where BG had chopped and sealed her supply while she was over the Atlantic.
For water, IME, that's only if you are doing the trenching. If water company do the trenching themselves, it will be 300mm.
That's how (leaks in both are very common, particularly nearby each other when ground moves), and water pressure is much higher than gas pressure in the street network.
In message , Andrew Gabriel writes
I can arrange a different route for the water supply and put ducts at
600mm for gas and electric. Until Phil mentioned red I assumed electric duct would be black. Where would one go to obtain this?Also, assuming an authorised alteration of an existing supply and pre-laid ducts, what are the likely fees?
>In message , Tim Lamb writes
Further investigation....
UK Power networks specify minimum 450mm depth (under garden) right angle turns with a specified radius and are happy with black duct which must be identified as electrical. Cost appears to start at ?956:-(
National grid want 425mm depth and yellow perforated 60mm duct, cost ?400 plus..
Everyone wants warning tape.
I put all mine in same trench - utilities were happy with that. Gas provided me with the pipe in advance I just lay in in trench and back filled. Leccy I put in old uPVC downpipes with a draw cord - only as I wanted to backfill before leccy turned up.
Water went in first, had it connected & tested, then partial backfill, then leccy ducting, backfill then gas pipe.
Officially Gas can insist on trench being left open to inspect depth ... I just put an offcut of 110mm drain pipe vertically over the pipe at 2 places in case they wanted to inspect - they didn't.
Most amazing thing to me was they connected gas to a stop c*ck in empty services cabinet and after purging line (vent to atmosphere) left it. No seal, just simple screw top. They said as they don't supply meter or sell the gas - not their issue. I mentioned what was to stop me connecting a regulator and running free gas for life - nothing.
Wonder how much of that goes on.
I was interested to see contractors doing gas pipe renewal locally. They had a calibrated board to drop into the trench, and took phone photos before backfilling.
Chris
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