one trench, 3 services?

Why not do them all at 750mm deep? - the 450mm for gas and electric is a minimum, not a maximum.

Is there any sort of requirement for separation of gas and electrical services? If someone sticks a JCB through a gas pipe, it's a lot more likely to go "bang!" if they went through a mains cable at the same time.

Its ok, the water would put the fire out :)

NT

they have to be about 250mm apart. when was that last time someone stuck a jcb through your front garden footpath?,

the 450mm is the max (18inches)

Depth of trench to top of cable or top of duct: -

Unmade ground, footway or grassland: 450mm Roadway: 800mm Agricultural: 1000mm

"In rough ground it may be necessary to excavate another 50 mm depth and lay a bedding of sand or other suitable fine backfill material."

I'm no expert at gas, but I'm not inclined to believe there's a maximum depth for a gas trench either.

Yep. I trenched my cables a lot deeper than that.

The deeper the better really.

The minimum depth of cover for a gas service on private property is 375mm. Half that of water. mark

It happens that mark formulated :

,,and the depth for water is to ensure it can never freeze.

So don't try and make your own ice cubes.

There was a long cold spell one winter, can't recall the year, but it was where I was living in the second half of the 1980's. Several peoples' water mains did freeze around me, and they were 18" down. For the first couple, the water company came around with giant jump leads and passed a high current through the steel pipes to thaw them. Then it started happen to too many other people, and they had to ration it to really needy cases only.

That made me think that if I ever needed to relay my water main, I would snake something like a 1mm^2 singles along it's length and bring the ends out accessibly. Probably wouldn't do anything else at that point, but if it later froze, I'd then work out how to pass something like 20A along it to provide gentle warming to the pipe.

Well at the regulation depth of 750mm for water the chances of it freezing in this country are quite remote. Now if had to be at 18" like your example and you could get it past the BCO then some heater wires might not be a bad idea.

The last time I hade the drive re-laid. OK, in my case it was a mini- digger rather than a full-blown JCB, but...

I know someone who put a MetPost through their gas main.

MBQ