Page 20 - Electrician - TT (Volume 1)

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Fig 5 Special powders have now been developed which are
capable of controlling and/or extinguishing this type of
fire.
The standard range of fire extinguishing agents is
inadequate or dangerous when dealing with metal fires.

Fire on electrical equipment.
Halon, Carbon dioxide, dry powder and vapourising
liquid (CTC) extinguishers can be used to deal with
fires in electrical equipment. Foam or liquid (eg. water)
extinguishers must not be used on electrical equipment
under any circumstances.
Types of Fire Extinguisher

Many types of fire extinguishers are available with different extinguishing ‘agents’ to deal with different classes of
fires. (Fig 6)

Fig 6

Water-filled extinguishers: There are two methods of operation. (Fig 7)
• Gas cartridge type
• Stored pressure type

With both methods of operation the discharge can be interruted as required, conserving the contents and
preventing unnecessary water damage.
Foam extinguishers (Fig 8):These may be of stored pressure or gas cartridge types.

Most suitable for
• flammable liquid fires
• running liquid fires
Must not be used on fires where electrical equipment is involved.

Fig 7 Fig 8

Dry powder extinguishers (Fig 9): Extinguishers fitted with dry powder may be of the gas cartridge or stored
pressure type. Appearance and method of operation is the same as that of the water-filled one. The main
distinguishing feature is the fork shaped nozzle. Powders have been developed to deal with class D fires.
Carbon dioxide (CO ): This type is easily distinguished by the distinctively shaped discharge horn. (Fig 10).
2

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CITS : Power - Electrician & Wireman - Lesson 1- 4 CITS : Power - Electrician & Wireman - Lesson 1- 4