Are good for tackling fires involving burning paper, wood and soft furnishings, as the water soaks into the materials (Class A fires). This type of extinguisher does not leave a residue, but does have a comparatively low rating. Due to this factor water extinguishers are larger and heavier to overcome their lacking in fire fighting power. It is important to remember that water is an electrolyte and conducts electricity. Care must therefore be taken with regards to accidental use on mains power. These problems can; however be overcome by installing water extinguishers with additive. This type of extinguisher has a higher fire rating, which therefore reduces the weight of the extinguisher and removes the risk of self-electrocution.