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Hazard

Electricity: Flooding incidents

Hazard Knowledge

Damage to electrical installations can have a significant effect on the immediate tactical options for incident commanders and can pose significant hazards to personnel and public. A property’s electricity supply may be affected by flood water or an element of the electrical transmission or distribution network may be affected.

Water can conduct electricity presenting a direct hazard to personnel and the public. Damage to electrical infrastructure could leave communities without electricity and have additional consequences that will affect the public and responding agencies.

Transmission system substations or overhead lines operate at significantly higher voltages (400kV or 275kV) than local distribution networks. Emergency services should keep away from transmission and distribution system substations and downed overhead line conductors that are affected by flooding until they receive notification from the owner or operator of the transmission system. Even in flood conditions it should be assumed all high voltage equipment remains live. Water pumping should be co-ordinated and controlled by the responsible person.

In most cases the primary conductors or equipment within substations are not affected by flooding. Secondary and ancillary services, such as the protection or control systems may be affected and pose a hazard. Hidden trenches also pose a significant risk of injury to staff and the emergency services when working in flooded substations.

Most infrastructure has some dependence on electrical supply and although back-up systems may be available, this may also be affected by flood waters. For example, many hospital back-up generators are in basements that can be affected by flooding.