This is for two major reasons, one of which and the most important is the possibility of danger to life and limb. The other consideration is of damage to the utility which can cause major problems and also has financial implications which could be considerable. If an underground service is damaged it means that at the very least the contractor will have to stop work on the site while the utility concerned sends out a team to repair it. The main digger hire Otago contractor may also impose penalties on the sub-contractor. For instance, if the power is shut off it could result in a local factory losing a day's production which could involve large amounts of money. If a worker is injured or even killed – and that does happen occasionally the claims for damages from the worker or his dependents could run into the hundreds of thousands of pounds.

Take a very simple example. A builder constructs a new housing estate next to a main road. The electricity company connects that estate to the grid, but for whatever reason does not update its'. Along comes a excavator hire Otago who needs to repair a water pipe running along underneath the pavement, and simply doesn't realise that there is now a live cable running underneath it to the housing estate.