Will a CAT scan pick up all services ? We have an issue at work where one of our employees has hit a gas pipe while digging a hole. He says he has carried out a CAT scan and also states that in his training they said it will not always pick everything up, will it be effective through concrete ? Thanks

Thanks for the reply, The works were being carried out for a main contractor for a local authorit. They survey what need to be done and send us a job sheet. Would it be up to them to send a service plan with the job sheet or would it be down to us to obtain the plan ourselves ? Thanks

Try the same CAT scanner near to where the pipe wasn't picked up, you'll soon find out if it did or not.

I'd just like to point out that hitting a gas or electric main will be costly too in more than monetary terms.

In answer to your question, no a CAT will not pick up all services. Pipes that cannot conduct a signal such as plastic gas or water pipes can't be traced with a CAT alone. A well known manufacturer of cable avoidance tools based in the Bristol area runs an excellent one day train the trainer course which is well worth attending. Regards Yul

Also, So it is a possibilty that the scan would have not picked up this gas pipe, So in reality we would require service plans for each council house we dig on ?

I'm open to a challenge on this, but I though the yellow pvc gas pipes had a metalic sleeving built into the wall of the pipe which the CAT could detect. Utility plans for the location you are digging? yes indeed, but I think you'll find that will only show you to the property boundary so for the council house situation they are of use if you are replacing say a fence on the boundary with the pavement but won't help if you are digging say a drain in the garden.

The Scanner alone will only pick up services where current is flowing and thus needs to be used with the genny in order to find other services where there is no current - this includes live cable tails that can be up to 50m long and not shown on services plans. Optic fibre cables used to have a tracer in the duct itself but I do note this feature is now becoming extinct!! By far the best bet is to use one of the specialist companies for the survey as they have much better trained operatives and equipment range to do the work. I would always look to the main contractor for service location drawings unless of course the contract says differently in an unambiguous way. Bob

Safezone In my experience when excavating in and around cables / pipes the supervisor overseeing the work should obtain the stats/ utility drawings , brief the operatives on the services in the area and have a permit to dig in place for the trial hole this will also include safe digging techniques ( hand only) the use of insulated tools ,flame proof overalls once the cable has been exposed then the main works can continue the competent person using the cat and genny must keep re scanning as the trial hole is being dug until located , you didn’t say if the service was struck with a shovel or a machine , also have you looked at when the cat scanner was last calibrated it may be faulty . If you have service drawings in place and the service clearly marked on the drawing there really should be no excuse for hitting the service in the first place Chris

Will a CAT pick up everything?? No... Cable locators will only pick up magnetic fields generated by power cables or other metalic pipes/cables which are in close proximity to a magnetic field, this is where the primary field is transmitted along other services. The other signal it can pick up is a radiated radio signal providing the service is again metallic and capable of re-radiating a signal, this will be dependant on exisiting signal frequencies in the area and the servie being long enough to act as an ariel. Locating a signal only tells you that something is there and does not identify what it is. Where a known service does not gie off a good signal a signal generator can be used to induce one into the service by different methods. You should always follow the information given in HSG 47 and the methods to avoid hitting anything used to the full...