HSG47 is a guide issued by the Health and Safety Executive that provides advice on the dangers of striking underground services when carrying out excavation work and how to avoid doing so. At Sygma Solutions, our HSG47 course goes into great detail about this because it is critically important to avoid striking underground services.

At the very least, doing so can hold up a contract while a utility comes out to carry out repairs, but very often a cable strike will result in serious injury to workers and can, on occasion be fatal. HSG47 gives an example of an incident where a worker died of his injuries in an explosion following damage to an 11,000-volt cable because the contracting company had failed to notify workers that there were live cables there and had failed to use adequate measure to avoid them being damaged. The company had to pay £210,000 in fines and costs.

Injuries caused by striking electricity cables are usually severe and caused by arcing current and any fire or flames that may result after penetrating a cable with a sharp tool. This can also happen if the cable is crushed and causes the conductors to suffer internal contact. Furthermore, other services nearby, such as gas pipes, may be at risk from damaged electrical cables, causing further risk of fire and explosion.

Gas Pipes

Direct damage to gas pipes can cause leaks that are immediate or cause a leak some time later on. Damage can occur when work is being carried out, or it could happen later if reinstatement is poor. The risk from LPG is greater than natural gas because it is heavier than air and can travel distances underground, and also accumulate in places such as a cellar.

Damage to water pipes can be less likely to cause injury, although a jet of water from a water main under pressure can do so. It can also propel stones or other objects in the soil through the air with it. Leaking pipes can also cause structural damage to the ground and other services.

Sewage pipes are mostly gravity fed, although some are under pressure. The main risk of damage to a sewage pipe is that of affecting the health of workers being exposed to raw sewage.

Flammable gases can also enter cable ducts and then accumulate in manholes and underground chambers presenting a risk to workers who need to work there.

Damage to telecoms cables and TV cables is unlikely to cause injury to workers, but the disruption to people who rely on the system can be considerable and the cost of repairs can be very expensive.

Wherever Possible, Work Must Be Planned To Avoid Underground Services

Our HSG47 course covers the HSE advice that a safe system of work has three elements, which are planning the work, detecting and identifying and marking underground services, and a safe excavation procedure. The best method is to plan work so that it avoids underground services, but if this is not possible and there are services in the area, plans must be made to minimise the risk of damage to the services. 

The HSE summaries the advice given in the guide as first of all planning the work, then surveying the site to locate and identify any underground services, and then reviewing the work to avoid disturbing services wherever possible.

Sufficient time and resources must be allowed to carry out the work safely. Even emergency work needs to be planned and an assessment of any risks arising from the work taken into account. The HSG47 course that we provide at Sygma Solutions, together with our other courses are all based around the location and identification of services so that work can proceed in safety.