Any contractor undertaking any sort of excavation work has to take into account the fact that there may very well be underground pipes and cables in exactly the place where the excavation is to take place. Obviously, if one is about to dig in a street where there are lampposts and shops there will be electricity cables running under the road or the pavement or both, but there could also be gas pipes, there will be water pipes, and there could be any number of other services such as fibre-optic cables and more.

One might be forgiven for thinking that this is obvious, but one might also think that there won't be anything there if one is going to dig in a quiet country lane. However, that is by no means necessarily the case. There could well be services running from one village to another, or there could be electricity cables and water pipes running to a secluded home that is surrounded by fields.

When carrying out excavation work, it is not just damage to the underground services that is the problem. Striking an electricity cable can result in serious injury, and in some instances is fatal. It can cause fire and explosions. Striking a gas pipe can also cause an explosion and fire. There is an additional risk from liquified petroleum gas as it is heavier than air and does not disperse easily. It can travel long distances underground and accumulate in basements or cellars for instance. It then only needs someone to go down there smoking a cigarette and the carnage would be immense.

Striking a water pipe may not be as bad, although water under pressure can shoot out of the ground and injure someone, particularly if it has stones or other objects in it that have been hurled out of the earth. It can also cause flooding and could easily cause the sides of an excavation to collapse.

Striking a sewage pipe could expose workers to raw sewage, and there could be environmental contamination and pollution.

Then of course, there can be collateral damage. As a minimum, the contractor has to stop work while the utility sends someone out to carry out repairs. There could be claims for damages from people whose supply has been cut off resulting in loss of business. The main contractor may impose penalties for the delay. There will certainly be massive claims for damages from people who have been injured in any way. The contractor concerned could also suffer damage to its' reputation.

The first port of call should always be the local utility providers who should be able to supply plans. Unfortunately, these are by no means always accurate nor are they necessarily complete. At best, they should be regarded as a guide. The safest approach is to assume that there are always buried utilities in the vicinity where one is to dig.

It follows that one has to use all means at one's disposal to help locate buried services in the vicinity. This means using a couple of tools known as the CAT and Genny. CAT stands for Cable Avoidance Tool and the Genny is a Signal Generator. The CAT is a hand-held tool that operates in one of three modes. In the Power mode it can detect power signals that are radiated by loaded cables. This is used to detect electricity cables.

In the Radio mode, the CAT can detect VLF radio signals re-radiated by buried metallic cables and pipes. This is used to locate gas, phone and communications lines, ducts and water services.

In the Genny mode the CAT is used in combination with the Genny and detects a tone radiated by the Genny to a buried conductor and can detect and locate all services as a direct connection to the source such as plug sockets, gas valves, water valves, and so on. The Genny can supply a direct connection to the utility or can provide an induced signal if direct connection is not possible. Signal clamping provides a direct connection to a pipe or live cable up to 76mmm in diameter without affecting the supply which is the most certain method of locating a power distribution system.