Response to Electrical Emergencies PDF

Standard Operating Guideline (SOG) Response To Electrical Emergencies Effective Date: 08/01/2010 Procedure Number 04-25A Revised Date: 01/01/2011 Number of Pages...

Standard Operating Guideline (SOG) Response To Electrical Emergencies Effective Date: 08/01/2010 Procedure Number 04-25A Revised Date: 01/01/2011 Number of Pages 03 1. Overview This plan is intended to adapt normal Standard Operating Guidelines (SOGs) to electrical emergencies. Details listed in this written document are designed to address the issues related to response to and mitigation of incidents involving wires down and energized electrical equipment. 2. Procedure Safety and Awareness Electricity always seeks its lowest level or a ground. It will choose any path it can to find a ground. A direct path to ground is when contact is made between something electrically energized and a portion of your body such as your hand, arm, head, or other body part. An indirect path to ground occurs when an object you are touching or holding comes in contact with something that is energized. Some of these examples could include tools you are working with, fences, vehicles, secondary wires, and any other objects that may be in with something energized. Gradient Voltage (Ground touch and step potential) When an energized source of electricity comes in contact with the ground, electric current can pass through the ground. Voltage is the strongest at the point of contact and becomes weaker as it radiates out from its source of energy. This electrical ground gradient creates differences in voltage and creates what is known as "step potential". An example of this is where electrical current could pass from a higher voltage point of contact such as one leg in contact with the ground to a lower voltage point of contact to the ground in the other leg. When this occurs the new circuit has been completed and there is a potential for a electrocution injury. This danger is identified by a tingling sensation in the feet and serves as a warning to stay back away from the area. This danger also becomes more pronounced and severe when the ground is wet or damp. Key points Downed power lines must always be considered energized with a potential lethal current. Lock out of power lines generally occurs after three operations or attempts to re-energize. Even though you may hear this, do not assume that the line is de-energized. Lines can also become re-energized or hot again by manual operation of a switch, automatic re-closing methods (either method from short or long distances away), by induction where a de-energized line can become hot if it is near a hot line, or through back feed conditions. Power lines may have reel memory where they curl or roll back on themselves when down. Use caution when applying water on or around energized electrical equipment. Hose streams can conduct current. Never spray lines directly and utilize fog stream and as little water as possible. The primary responsibility is to protect exposures, not extinguishing burning wires or electrical equipment. Pad mounted and overhead transformers can explode. PCB hazards. Smoke can be potentially fatal. Avoid and contain pools of oil around the transformer. Voltage can travel through both dry and wet ground for considerable distances. Equipment can still contain energized electrical potential until grounded. Electricity can flow through the ground or other conductive objects such as fences from a point that may be far from the scene. 04-25A Response to Electrical Emergencies SOG, Page 1 of 3 Size Up Determine the type of electrical problem and request the appropriate power company to respond. Update dispatch with the proper location of the incident (pole number, etc.) if it can safely be obtained. If not, obtain closest address or adjacent pole number. Set up a safety perimeter (rule of thumb is to maintain distance of one span of wires on either side of fallen wires). Electrical contact with adjacent objects may require a larger perimeter area. Perimeter should be maintained and sufficiently staffed to ensure unauthorized personnel from entering restricted area until power is disconnected by appropriate power company. Park apparatus outside operational perimeter. Downed Power Lines Consider all downed wires as energized. Locate both ends of downed wires. Place apparatus away from downed lines and power poles, and consider additional lines that may fall during incident. Establish safety perimeter, secure area and deny entry. Operational safety perimeter fences, vehicles, guard rails, railroad tracks and water may become energized. In the event of multiple lines or poles down over a large area, call for additional resources. Traffic control measures shall be initiated in the event that a roadway is impacted. Request Police Department for traffic control, if necessary. Stand-by and ensure public is kept away until responsible power company is on scene and de-energizes power line(s). Power Lines on Vehicles Consider all downed wires as energized. Do not touch vehicle(s). Establish safety perimeter, secure area and deny entry. Instruct occupants to remain inside vehicle until power is secured by Power Company and they are instructed it is safe to exit. If occupants must leave vehicle, due to fire or other life threat, instruct them to open the door, not to step out. They should jump free of the vehicle without touching the vehicle and the ground at the same time. Fire personnel should not try to remove or treat victims until power company personnel have de-energized lines. Stand-by and ensure public is kept away until responsible power company is on scene and de-energizes power line(s). Sub-Stations and Transformers Consider all electrical equipment and power lines as energized. Establish safety perimeter. If sub-station or transformer(s) have a perimeter fence, stay outside fence. Secure area and deny entry. Protect exposures. Consider overhead lines that may become involved or fall due to an overhead transformer or sub-station equipment being involved. Do not walk under transformers. Transformers contain PCB's or other types of oils, which are hazardous. Stand-by and ensure public is kept away until responsible power company is on scene and de-energizes transformer(s) and/or equipment. Underground Vaults Do not enter underground vaults for any reason. Underground vaults are a confined space and Heavy Rescue Team response should be considered Consider all underground vaults to contain energized wires or equipment. 04-25A Response to Electrical Emergencies SOG, Page 2 of 3  Do not open shutters on vaults as this may cause an explosion by igniting trapped, flammable gases. Stand clear of manhole covers. Pressure builds up or an explosion may cause manhole covers to blow off. Stand-by and await responsible power company to de-energize vault equipment. Electrical Firefighting A fire attack on a fire caused by energized electrical sources shall not be attempted until confirmation by responsible power company that power has been de-energized. Fire suppression efforts should be directed toward threatened exposures outside the hot zone. A hot zone being defined as the area impacted by energized electrical source. Do not attempt to extinguish pole fires using water unless life is threatened or pole is at risk of structural failure or if directed by responsible power company. CO2 or dry chemical extinguishers are the recommended method for extinguishing electrical fires. If a structure fire involves energized electrical equipment, service or wires, power to the building should be shut off. Electrical vault fires should be extinguished only after all power has been disconnected. 04-25A Response to Electrical Emergencies SOG, Page 3 of 3