Incidents involving electricity Flashcards
Any mistakes or suggestions, please contact Phil Simpson
Incidents involving electricity
Electricity company premises include?
- power stations,
- sub-stations,
- fenced enclosures containing transformers and other electrical distribution equipment,
- distribution cables/equipment (including cables mounted on poles, towers and pylons and those run underground)
(Policy 769, 1.3)
Incidents involving electricity
In a fire situation, what hazards should be considered?
- large quantities of fuel may be stored within power generating stations.
- oil filled transformers and switchgear may fail and explode without warning.
- insulating materials, e.g. paper, oil or plastics, may create a large amount of toxic, irritant smoke.
(Policy 769, 2.2)
Incidents involving electricity
Some transformers and switchgear are protected by what fixed installations?
Fixed installations which when operated, will fill compartments with carbon dioxide or vaporising liquid, this may cause asphyxiation
Incidents involving electricity
Crews must not pass warning signs or gain access into areas which have warning signs restricting access until when?
A responsible or authorised person is in attendance
Incidents involving electricity
The attendance time for the authorised person may take up to how many hours?
2 Hours
Incidents involving electricity
Sub-stations sited within buildings will be situated against an outside wall and are constructed to provide how many hours fire protection?
4 hours
(Policy 769, 1.4)
Incidents involving electricity
What minimum distance is a 45mm jet to be from electrical pylons?
20m
Incidents involving electricity
What minimum distance is a monitor to be kept from electrical pylons?
30m
Incidents involving electricity
When carrying out a rescue in the vicinity of OLE, sub-stations and other electrical equipment belonging to the electrical supply industry what is the minimum safe approach distance?
5 meters
Incidents involving electricity
What are the considerations when En-route to a possible incident involving electricity?
- ensure all personnel are rigged in PPE
- MDTs
- brief crews as to the nature and extent of the involvement of electrical apparatus.
- consider RVP’s
Incidents involving electricity
What are the on arrival and operational procedure/considerations to a incident involving electricity?
- Attend main entrance or pre-determined rendezvous point (RVP) and liaise with responsible person.
- Establish appropriate cordons and hazard zones
- Confirm nature of incident, carry out a DRA using DMM and formulate a plan.
- Fully brief crews before committing and ensure water is not applied directly onto live electrical circuits
- Look for and act upon signage indicating the presence of high or low voltage apparatus or any signage restricting access
- Do not break any securing devices or pass warning signs unless it has been confirmed that it is safe to do so by an authorised person on site. Do not enter or commence firefighting until the power is isolated and the equipment made safe.
- If the power is not isolated, do not attempt any rescue, do not attempt to gain access and do not apply water directly. Request the urgent attendance of an electricity company representative via Brigade Control (unless an ‘authorised person’ is already present).
- Do not manoeuvre ladders, equipment or appliances in close proximity to any live equipment, if working close to overhead power lines maintain a safe distance
- If the voltage is known to be less than 3300V, electrical gloves may be used to isolate damaged apparatus.
- If firefighting can not commence due to live power supplies, protect the surrounding risk, where safe to do so, with appropriate firefighting media.
- Secure a water supply if a fire is likely to be tackled by the use of water or foam and assess whether any additional resources are required, such as firefighting foam.
- Consider containing incident run off and informing environmental agencies.
Incidents involving electricity
What are the end of incident actions the IC should ensure are carried out ?
Utility tags should be affixed to the supply.
The incident will be handed over to the occupier, relevant authority and/or Police Service. Issues regarding the safety of any damaged or displaced solar panels and the risk from DC electricity should be brought to the attention of occupiers and other agencies on scene.
Incidents involving electricity
How are power stations generally powered?
Generally powered by a range of methods including fossil fuels such as coal, oil, gas or wood chip.
Incidents involving electricity
At premises where a sub-station has been provided within a building, Where would you expect to find the chamber/transformer?
The transformer chamber/sub-station will be situated against an outer wall. The walls and floors separating it from the remainder of the building.
Incidents involving electricity
At premises where a sub-station has been provided within a building, How much fire resistance will the floors and walls have?
At least 4 hours
Incidents involving electricity
Why do incidents that involve smoking issuing from pavements or explosions from manhole covers present a risk to firefighters?
Incidents of this nature present a genuine hazard to crews, in the past attending crews have been injured whilst removing inspection covers or in trying to access ducting at the point an explosion has occurred.
Incidents involving electricity
What are the main hazards associated with Incidents involving electricity ?
- electric shock
- Illegal activity and overloading
- fire
- explosion
- hazardous gases or liquids
- trip hazards
Incidents involving electricity
What are the ‘explosion hazards’ associated when attending Incidents involving electricity?
- Short circuiting and associated violent electrical arcing can cause an explosion in pavement level electrical ducting. These explosions can be violent enough to damage pavements and lift inspection covers, scattering debris over a significant area.
- Fires in cable insulation even when arcing is not present can create sufficient over pressures to dislodge inspection covers allowing smoke to issue.
Incidents involving electricity
If called to smoke issuing or explosion from inspection pit, what shoud be the crews actions?
- Carry out DRA
- Do not approach or attempt to lift cover
- Evacuate people from immediate vicinty
- Implement appropriate size hazard zone
- Identify type of pit/cover asap
- request urgent attendance of relevant authority
- Lay covering jet
- Do not extinguish, cover suurounding risks
Incidents involving electricity
Electrical rubber gloves provide protection up to what voltage?
3300 Volts
(Policy 769, 6.28)
Incidents involving electricity
What are the limitations/restrictions on firefighting when in or near to electrical instalations?
- If firefighting can not commence due to live power supplies, protect the surrounding risk, where safe to do so, with appropriate firefighting media.
- Secure a water supply if a fire is likely to be tackled by the use of water or foam and assess whether any additional resources are required, such as firefighting foam.
- Consider containing incident run off and informing environmental agencies.
Incidents involving electricity
What are the restrictions/limitations on the use of ladders/aerial appliances at sub-stations?
Ladders and aerial appliances should not be used at external sub-stations without an assurance from the authorised person that it is safe to do so, and any equipment should be at least 10 metres from them. Attention should be paid to prevailing weather conditions as these will affect the movement of cables and visibility
Incidents involving electricity
What is the minimum distance aerial appliance or ground monitors are permitted near live conductors?
Ground and aerial appliance monitors should not be used within 30 metres of the live conductor
Incidents involving electricity
What information should be available to help identify the owner/operator of a pylon/sub station?
National grid pylons and energy operators’ premises will have unique markings/ identification plates, this information must be included in any messages requesting the attendance of a representative from either organisation
Incidents involving electricity
What ideally should be the correct extinguishing media when dealing with incidents involving delicate and complex apparatus such as that found in switchboards in generating stations, substations, telephone exchanges, or other electronic equipment such as computers?
Carbon dioxide or vaporising liquids as they do not damage electrical equipment
Incidents involving electricity
What are the main hazards when working near overhead power lines ?
In the case of high voltage overhead power lines there is the possibility of ‘arcing’ from a conductor to earth/ ground or adjacent structures, trees or fire brigade equipment when there is dense smoke or flames rising close to the conductors and which may be affected by the prevailing weather conditions.
Incidents involving electricity
What control measures need to be implmented when when working near overhead power lines ?
When working near overhead power lines, firefighters should avoid positioning themselves or their equipment within a ‘corridor’ 10 metres either side of the overhead power line (measured along the ground).
Incidents involving electricity
What risk is present from Wind turbines and solar panels following isolation?
There remains the risk of low voltage electricity discharge and LFB electrical gloves should be worn.
Incidents involving electricity
What are Uninterruptible power supplies (UPS) ?
In some premises there are auxiliary means to provide electrical power in the event that the national grid /energy provider fails to maintain a constant supply. These may be generators powered by fossil fuels, and/or battery banks. In both cases they will need to be isolated or switched off if they present a hazard in the area of operations.
Incidents involving electricity
What hazard do battery banks present following isolation?
The batteries will remain live until such time as they have been drained of power. Any isolation of the battery bank is only related to the circuits they provide power for, and as such the battery bank remains a live hazard. Unless otherwise marked they are low voltage and LFB electrical gloves provide adequate protection from electrical shock. Batteries used are predominantly variants of lead/acid, and if damaged the contents are likely to pose a hazardous materials risk.
