Cable / Pipe Finders - Useful or waste of time?

[Newboy]

My earlier post was made partly in jest but with a degree of seriousness.

Don't underestimate the risks of hitting live services - remember that hitting a LV cable causing significant damage it's likely that the cable will stay live as the fusing at the substation can be something like 500 amps.

To put it into context, a relative experienced a power failure a couple of weeks ago as a result of one of her neighbours trenching across an unmade road. Power cable identified and avoided but disturbed, about 48 hours later a loud bang, followed by smoke billowing up from the now back-filled trench. Power lost to over 600 dwellings and the neighbour is now in discussion with the distribution company about costs.

 

[Agile]

With a distance of 17m, and if you are not so keen on hand digging to a minimum of 750 mm, then you could consider having the new pipe moled in.

Also remember that with a blue plastic pipe you don't have to trench in a straight line so could choose a routing to keep it further away from gas and electric supplies.

As far as I recall, the usual CAT is pretty good at following mains cable based on detecting the 50 Hz radiated field.

But they only detect pipes from a signal injected from their generator and that can be rather less accurate.

But if your water pipe is steel then it may be possible to locate it using a metal detector.


Must remember to find my CAT and build a genny for it!

Tony

 

[Newboy]

new pipe moled in

Who's going to mole a pipe in an area know to contain other services?

As far as I recall, the usual CAT is pretty good at following mains cable based on detecting the 50 Hz radiated field.

But they only detect pipes from a signal injected from their generator and that can be rather less accurate.

Your recollection is getting worse!

 

[Agile]

It always surprises me just how blasé those doing moling can be.

I can only assume they expect the vertical separation will protect them!

But my gas and water both come in from the street at about 800 mm down. Electricity about 300 mm down.

 

[GoodDIYjob]

Yes, I had an email quote for moling the 17M and sleeving to inside the property, at a price I'd accept, but based on a site visit from another moling company, I'm not sure it would be the right idea.

The other guys said, he'd prefer to trench as it is 3 or 4 pits anyway, plus the ground make up and proximity to clay sewer lines (and other services) could make it the wrong choice, once the mole goes off trajectory.

The other guys who quoted via email will probably walk away once they get here! Or maybe worse do the job and leave me with a new MDPE water line through old clayware...

I've rung a few ground workers, some twice, none called back yet!

I'm thinking I may hire a cat 4 from a survey company and see if it gives me comfort where things run and maybe dig the trench by hand myself. At best only 10M of the run can be done mechanically anyway, maybe less..... If I know where the services are as they approach the house, my aim would be to trace them out to their entry at the drive. I'd know then the separation I'm dealing with. If they are on the opposite side of the drive to water separation would be fine.

The water pipe is old galv steel and the Gas original (iron?), so I'd have to hook the genny up to those inside the house. Start from where I know they exit past the house, and follow them out the drive.

 

[rules&rulers]

Have a drive around your area,look out for utility contractors working on gas/water pipe services,if they have a mini digger,compressor,jack hammers then you have the correct people.

Have a friendly chat with them,show them photos of your site and ask them if they are interested in a cash job or know anyone who is.

 

[Nige F]

Gas and water are both (technically) steel . If you like I can sell you an ex SEEBOARD trenching spade (graft) with a foot of the handle covered in black PVC insulating tape. Must've been safe, back in the day

 

[GoodDIYjob]

Yes, thanks. Or I could just find a roll of UK Power Networks approved PVC Electrical Tape...

 

[Nige F]

Or even better a roll of British Railways Navvy handle tape - as used on the Southern Region 3rd. Rail system

 

[rules&rulers]

Nigel F FS thats a helpful post,

 

[Agile]

With his trenching spade and navvy tape he must have been a labourer!

 

[rules&rulers]

Tony has nailed it again,

Navvy is required.

GoodDIYjob if you like labour only to dig out a trench and refill after you lay your pipe (oh matron) then i have contacts in the travelling community and they are local to you.Very close to you.

Good luck,