In case of a fire, before the firemen use the water, they shut off the main electrical supply for the area. Explain why they do this. [2 marks]

Regular water contains dissolved salts and minerals and is thus a good conductor of electricity.
(0.5 Marks)
Firemen use regular water to put out fires. If firemen pour water on the fire, the electrical appliances near the fire may get wet. If anybody touches those appliances they may get electric shock.
(1 Marks)
In order to avoid people getting electric shock due to wet electrical appliances, the firemen shut off electrical supply before they use water.
(0.5 Marks)