13 - ELECTRICAL SAFETY
The danger of injury from electricity exists in most instances where electric energy is used. Injuries can happen through electric shock, electrically-induced fires or heat burns. Under certain conditions people can be injured severely even from relatively low voltages (coupled with high current flows). The amount of current necessary to seriously harm or kill a person is small (<10 milliampere alternating current), and it is particularly easy to reach dangerous levels of current flow if the skin is wet or even damp with perspiration. Although contact with high voltage at low current flow is not necessarily lethal, it can still produce severe tissue damage at the site of contact.
General Safe Work Practices
- Personnel conducting electrical work must be licensed as required by the District Department of Consumer and Regulatory Affairs (DCRA).
- Always comply with established safety procedures beginning with pre-site assessments and written plans or procedures when required.
- Management, Staff and Contract Personnel shall provide installation details necessary to complete tasks and report work deficiencies (observed and/or anticipated) to the appropriate University Facilities Maintenance and Operations (FMO) manager(s).
- Staff and contract personnel shall be advised of known hazards associated with work to be performed. Conversely laborers shall advise FMO management of un-divulged hazards found during the performance of approved work.
- Show abatement procedures for found deficiencies.
- Follow any applicable written FMO protocols, NFPA 70E, and best industry practices*.
- Preferred operation should be on de-energized circuits.
- Where necessary implement use of an Energized Electrical Safety Form and associated work controls, i.e.. Eye wear ANSI or ASTM-approved Personal Protective Equipment (PPE), rated clothing, gloves, eye and face protection. Utilize whenever there is danger of injury from electric arcs*, flashes, shock or flying objects due to electrical explosion.
- Immediately stop using electric equipment that runs erratically or when its use produces an electrical tingle, as these are warnings that an electrical problem exists which could cause dangerous shock injuries. Tag the equipment as defective and have it repaired before reuse.
- Circuit breakers are not designed to protect people from electric shock; their function is to prevent wiring overloads leading to fires. Similarly, equipment fuses are designed solely to protect equipment and are generally worthless in terms of personal protection.
- Determine all possible electrical power supply sources.
- Keep all diagrams current if possible (especially single line drawings).
- For fire prevention, keep all combustible items (plastics, fabric, lumber, solvents, etc.) at least18 inches away from electric heaters or other heat-producing equipment.
- When operating energized electric equipment or flexible cord sets in highly conductive environments (e.g., areas inundated with water) use only equipment which is specifically designed to operate safely in such environments. Ground fault circuit interruption devices may be sufficient in some cases.
- Do not energize electric equipment capable of releasing sufficient electric or heat energy to ignite a flammable air mixture, until sufficient ventilation is established to prevent the accumulation of ignitable fuel/air concentrations. Such flammable fuels include solvents, paints, glues, and other volatile combustible materials.
* Please refer to the American Trainco in-service training for Electrical Safety conducted in conjunction with the University Facilities Maintenance and Operations department. Personnel performing electrical work are required to participate and satisfactorily complete annual electrical safety/arc flash training class. In addition, monthly in-house reviews are conducted with Facilities electrical personnel.
Flexible Electric (not extension) Cords
- Use only flexible cords and cables containing an equipment grounding conductor (a three-prong plug) to power electrical equipment that is not hard-wired. This does not include portable tools protected through built-in double insulation.
- Do not alter or modify attachment plugs or receptacles in any manner that disrupts continuity of the equipment grounding conductor.
- Do not use plug adapters which interrupt the continuity of the equipment grounding connection with tools or equipment designed with grounding prongs. However, plug adapters with pigtails attached to an electric ground are allowed provided proper fail-safe protection is engineered.
- Do not overload circuits with multiple attachments to a single outlet.
- Before each use, visibly inspect all flexible cord sets, including extension cords, for external damage (e.g., dry-rotted casings, loose plug heads, cut casings, missing ground pins, etc.) Do not use defective cords; dispose only, do not repair. Use new cords.
- Do not unplug an electric device by pulling the cord as this stress can cause internal cord cause short circuits.
- To prevent internal damage leading to electrical shorts, do not use electric cords to hoist or lower electric equipment or tools. For the same reason, do not fasten flexible cords with staples or locate them in areas where doors, drawers or other equipment could pinch and damage insulation.
- Where capacity permits, use surge protectors preferentially and never plug surge protectors into one another.
Working With Test Instruments/Equipment
- Test electric circuits only if you have been qualified to use test equipment and work safely on energized circuits.
- De-energize live components before starting work on them. Wear appropriate FR rated Personal Protective Equipment or PPE. Stand to the side of operating switches when engaging them. Do not reach blindly into areas which may contain energized components.
- Visually verify open blades if possible. Open disconnecting device for each circuit. Exceptions would be if de- energizing components increases hazards or is infeasible due to equipment design or with circuits operating at less than 50 volts to ground when there is no risk from arc-induced burns or explosions. If provisions for temporary power outages have been approved and documented. Use proper lockout/tagout procedures.
- Complete a function test of de-energized equipment with test instruments before working on circuits or components of electrical systems.
- Test to verify the circuit is de-energized
- Verify the meter by testing a known source
- Verify the circuit is de-energized
- Retest meter on a known source
- Test phase to ground and phase to phase
- When working near exposed circuit parts that are or may become energized, assume that all exposed conductors and circuit components are energized and dangerous.
- Use suitably insulated tools and equipment when working near exposed energized conductors or circuit components where it is possible for the tools or equipment to make accidental contact with the conductor or component.
- Visibly inspect test instruments/equipment and all associated leads, cables, power cords, probes and similar connectors for damage before each new use. Do not use defective items; dispose. Do not repair them.
- Use fuse handling equipment, suitably insulated and rated for the circuit voltage, to install or remove fuses from electric components.
- Do not wear conductive articles of jewelry and clothing (e.g., rings, watch bands, bracelets, necklaces, key chains, metallic aprons, metal headgear, etc.) where they present an electrical contact hazard with exposed energized components.
- Handle conductive materials and equipment that are in contact with any part of your body in a manner that will prevent accidental contact with exposed energized conductors or circuit parts. Such materials and equipment include pipes, tubing, hoses, ropes, metal lined rules, steel tapes, chains, etc.
- Use protective shields, barriers, or appropriate insulating materials to protect yourself from shock, burns, or other electrically-induced injuries when working near exposed energized components or where dangerous electric heating or arcing is possible (includes fuses and circuit breakers).
- Do not use metal ladders or ladders with longitudinal metal reinforcement when working on or in the proximity of exposed energized circuits.
- Maintain a safe distance from conductors when working near energized overhead lines.
Isolation of Electrically Hazardous Areas
- Designate safe approach boundaries for Electrically Safe Work Conditions.
- Use nonconductive barricades in conjunction with safety signs wherever it is necessary to prevent access to areas with un-insulated energized conductors or circuits.
- Guard live parts of electric equipment operating at 50 volts or higher against accidental contact by using suitable housings and insulation or by location in enclosures/rooms accessible only by qualified personnel.
- Apply properly rated ground clamps and jumpers where needed.
- Re-iterate proper use of lockout/tagout procedures when working on electrical circuits or electrically powered devices.