When selecting fire extinguishers for live electrical equipment it is important to understand which extinguishers are effective and safe, as there is otherwise a risk of electrocution.
Electrically safe fire extinguishers have undergone dielectric testing to ensure the fire fighting agent are safe on or near live electricity. Traditionally, water based extinguishers, even with AFFF foams, have been unsuitable for use on electrical equipment fires; however, the use of de-ionised water in water mist extinguishers or the use of some specially designed spray nozzles now allows use of some water-based extinguishers on electrical fires. Below we have listed extinguishers suitable for use with live electrical equipment (less than 1000V and more than 1m distance).
Dielectrical testing verifies that even with an incredibly high voltage of 35000 Volt, no electrical current can flow back to the person discharging an extinguisher on a fire involving live electricity. Certain test distances between user and fire apply for this test. Once the extinguisher has passed this stringent test, it is still limited for safety reasons for use on maximum 1000V and a minimum distance between extinguisher and fire of 1 meter (1000V is four times the voltage used in a domestic building!).
If a liquid is used on a fire involving live electricity there is still a risk of a pool of liquid forming and if this liquid is able to transport current there could be a risk to the user from electrocution if the user stands in the pool. However, one has to keep in mind that the use of any liquid on live electrical equipment usually leads to immediate fuse-triggering. So the pooling issue is more theoretical.
Our dry water mist extinguishers apply de-ionisde water and discharge an extremely fine spray. Pooling is almost impossible and in addition, de-ionised water cannot carry electrical current, so dry water mist extinguishers are a new option to fight electrical fires and cause minimum damage to the equipment on fire by the fire fighting agent.
Strictly speaking there is no such thing as electrical fire, as electricity does not burn. Neither do the cable cores and other conductors. However, electrical current can heat up other materials and start fires. Often, it is the cable covering or foreign bodies in the electric equipment start start to burn first.
If the electric supply to the equipment on fire continues we speak of a fire involving live electrical equipment and the use of, for example, a simple water extinguisher could lead to electrocution of the person fighting the fire. When planning extinguishers for your business or home you therefore need to consider the electrical equipment eg laptops, printers, kettles or washing machines. Our section of electrically safe extinguishers will help you select a suitable extinguisher for your building or application.
Which extinguishers are suitable for electric equipment?
Traditionally, CO2 extinguishers are used for electric equipment, as the CO2 gas does not carry electricity. However, CO2 gas can drift off and the fire can re-ignite.
Powder extinguishers were also used in the past, as they are powerful and do not conduct electricity. However, they are not recommended for use indoors any longer, as they cause inhalation issues and can cloud the escape route.
Some foam extinguishers are dielectrically tested and can therefore be used on or near the fire. You need to carefully read the product description to see if the focus in on 'near' or actually 'on' live electrical fires.
A new solution are dry water mist extinguishers using de-ionised water which cannot conduct electricity combined with a very fine mist generation that does not pool and protects the user from both fire and electrocution.