Basic Electrical

Question 1

What is the safe approach distance for a fallen distribution line and a transmission line?

Answer 1

Distribution line - 8M
Transmission line - 20M

Question 2

List 5 hazards that may be present at a substation?

Answer 2

◼Compressed Gas
◼High voltage (HV)
◼ Polychlorinated biphenyls (PCBs) in transformers and capacitors
◼ Residual power after isolation – in the capacitor banks
◼ Oils used for cooling – use foam to extinguish.
◼ Stairs close to entry
◼ Confined space

Question 3

What is non-contact AC Voltage tester used for?

Answer 3

The non-contact voltage detector is used to, but is not limited to:
◼ Determine the location of electrical hazards at structure fires by firefighters tasked to
enter a scene where POWER has not been isolated.
◼ To determine, after power has been isolated, that other sources of power such as
illegal electrical connections, are not present.
◼ Identify whether a component, such as metal fencing, street furniture, or anything in
contact with it, is energised

Question 4

What is Step-Voltage?

Answer 4

When feet are placed on different voltage rings, electricity equal to the flow of rings will flow through the body. Eg 800-600V = 200V flowing through body

Question 5

What is Touch Potential?

Answer 5

When touching a wire or energised object while standing with feet on the same voltage ring, voltage equal to the difference between the wire and the voltage ring will flow through the body.

1200V - 600V = 600V.
600 volts will pass through the
firefighter.

Question 6

What safety considerations should you adhere to when entering in substations?

Answer 6

FF shall not enter unless accompanied by electrical supply company representative
or other trained persons
- Entry and internal FF only to commence after clearance given by electrical supply
company that its safe to do so
- Treat all equipment as live