Risk of electrocution during fire suppression activities involving photovoltaic systems

• Risk of electric shock in firefighting activities involving PV systems is studied.
• Current flowing through the water stream between nozzle and target is measured.
• Safe distances to be respected during firefighting are worked out.
• Conductivity of streams, constituted by water mixed with air, is characterized.

Firefighting activities regarding buildings normally require electric power to be disconnected before a water jet is used, in order to minimize the risk of electrocution. As for as concerns Photovoltaic Systems, during a fire event it is not possible to turn off the whole power system in order to guarantee that all the components are de-energized. The object of this paper is to estimate the safe distances to respect during firefighting involving PV Systems. To this end a series of experimental tests have been performed, in order to measure the current flowing through the water stream, under different conditions of nozzle design, jet shape, water pressure and stream length. Experimental results have been compared with data in literature. Moreover, the electrical conductivity of the water streams, which actually consists of water mixed with air, has been evaluated.