UTILITIES

Question 1

SOGs state - In some cases, mostly at larger structures and complexes it may not be appropriate to turn off power to the entire structure. List three of these structures or complexes.

Answer 1

• INDUSTRIAL COMPLEXES: Some processes may be difficult to shut down quickly
• HIGH-RISE BUILDINGS: Lights or lifts may be needed during evacuation of residents
• HEALTH CARE FACILITIES: Life-sustaining equipment may be in use

Question 2

During a bushfire, your sector contains an area where trees and grass are alight under high voltage power lines. According to SOGs, what are the safe working distances and what firefighting activities can you perform?

Answer 2

• Keep people and vehicles a minimum of 25m clear of a fire burning under or near power lines
• Do not engage in firefighting under high voltage lines, only approach within 25m of the power lines to mop up grass fires.

Question 3

According to SOGs, if CO2 is used to extinguish a fire in an underground vault substation what is the minimum time it needs to be kept sealed within the vault?

Answer 3

• Upon discharge of the gas, keep the vault closed and openings sealed for at least 20 minutes.

Question 4

According to STP, there are two control measures when dealing with live power at an incident. List and describe them.

Answer 4

1. TURNING OFF POWER: Involves switching off the main switch, removing fuses, and switching off circuit breakers at the switchboard. This removes power from the circuits within the structure supplied through that switchboard. When power is turned off at the switchboard, the wiring from the electricity network to the switchboard remains live until the power is isolated by the electricity company.
2. ISOLATING POWER: is the best way to control an electrical hazard but this can only be done by the electricity company, and this takes time. The electricity company needs to drive to the site, work out how the power is supplied and then disconnect the power from the network to the site. As an interim measure, FFs can turn off power at the switchboard

Question 5

According to STP - Firefighters can ‘turn off’ a solar power system to stop electricity feeding into the structure’s circuits or back to the electricity network if configured to do so. State the recommended procedure.

Answer 5

1. ON-SITE CONSULTATION: determine whether it is appropriate to turn solar power system off and how best to do it
2. ASSUME SWITCHBOARD IS LIVE: don electrical safety gloves then over-gloves. Have your helmet visor down and look away
3. FOLLOW THE SHUTDOWN PROCEDURE: this may be on or near the switchboard or inverter. If not found, turn off the inverter main switch then turn off the solar panel main switch
4. CONSIDER IF BENEFITS OUTWEIGH RISKS: restrict work as far as reasonably practical to that required to protect life or prevent dangerous expansion of the incident
5. ISOLATE THE POWER: if required, have the owner/occupier contact their electrician to isolate the power

Question 6

According to STP -When a battery energy storage system is present at a residence, there should be an indicator to alert you to this. What is an example of an indicator, located outside the switchboard.

Answer 6

• An ES sticker. There should also be data sheets, or further information about this type of system

Question 7

According to STP - If solar panels, or the attached isolators, are on fire, in addition to the considerations with turning off an alternative power source what actions should firefighters take?

Answer 7

• Conduct firefighting from the ground or an aerial appliance. Do not get onto the roof to extinguish the fire. Do not put a ladder against the roof as the gutter may be electrified.
• Extinguish the fire with a spray nozzle, using a pulse spray in a dispersed pattern. If the solar panel is at ground level, consider using CO2 to extinguish the fire, ensuring that there is at least 250mm air gap between the CO2 extinguisher nozzle and any electrified components.
• NB: NSW Fair Trading notification form to be completed at completion of incident

Question 8

According to the guideline support document for electricity SOGs - Electrical transformers in high density areas of cities maybe situated in underground vaults, if a fire occurs in one of these vaults, CO2 can be injected via a wall mounted or footpath CO2 connection box. What does the number on the connection box indicate?

Answer 8

• The number of CO2 cylinders required to be injected is indicated on the connection box.

Question 9

According to the guideline support document for electricity SOGs - What factors affect voltage gradient at wires down?

Answer 9

• Voltage gradient varies depending on:
  o Composition of the ground – eg concrete, road surface, soil
  o Moisture content
  o Voltage of the electrical source

Question 10

According to the guideline support document for electricity SOGs - Conductors allow electricity to easily pass through them. List five conductors.

Answer 10

1. Metals (copper, aluminium, steel) incl ladders, fences, gutters, roofing
2. Human Body
3. Timber and Trees
4. Flame and Dense Smoke
5. Vehicle Tyres
6. Some fire extinguishing mediums
7. Wet or dirty rope
8. Water – including hose lines

Question 11

According to the guideline support document for electricity SOGs - Name four measures to control the risks associated with electricity.

Answer 11

1. Stay away from the hazard. Always regard it as live until you know otherwise.
2. Assess the risks from at least 8 metres.
3. If suspected, establish Exclusion Zone.
4. Elec company isolate power.

Question 12

As listed on the SIMS Worksheet: Electrical safety kit - State the inventory stored in the green canvas bag of the electrical safety kit.

Answer 12

• 1 x pair of insulating gloves
• 1 x pair of leather overgloves
• 1 x electrical safety kit bag
• 2 x non contact AC voltage detectors, either Modiewark Rescue or GLM Mini Rescue

Question 13

According to Recommended practice - When using the gloves from the electrical safety kit, what is the correct donning sequence?

Answer 13

1. Don electrical gloves first
2. Don over gloves second
3. The cuff of the electrical glove must extend past the cuff of the over glove
4. The cuff of the electrical glove must be above the cuffs and sleeves of your PPC