Final answer:
The fire extinguisher safe for electrical fires is marked with a star, 'E', or 'Class C'. Water should not be used on such fires due to its conductive properties, which can cause electrocution or spread the fire. Safety devices like circuit breakers help prevent electrical hazards.
Step-by-step explanation:
The symbol on a fire extinguisher that is safe to use on an electrical fire is not represented by the NFPA 704 Hazard Identification System, but rather by a specific label indicating its suitability for electrical fires, often represented by a star or the letter 'E' or the words 'Class C' within a blue circle. We are advised not to flick electric switches with wet hands, as water is an excellent conductor of electricity and could lead to electrocution. Furthermore, we should not throw water on electrical fires because water conducts electricity and can lead to electrical shock, as well as potentially spreading the fire if the water reaches other electrical sources. Instead, the use of a CO2, dry chemical, or foam extinguisher, which do not conduct electricity, is recommended for extinguishing electrical fires.
Electrical safety systems and devices, such as circuit breakers and fuses, are used to prevent thermal and shock hazards by interrupting excessive currents. The three-wire system further adds to the electrical safety by grounding the neutral wire and the appliance's case, reducing the risk of electric shocks.