Electrical Safety

Electricity is an important and engaging topic in physical science courses. Student investigations and demonstrations may involve circuits, static electricity, electrical equipment, generators, sensors, power supplies, and other devices that support meaningful learning. Additionally, general electrical hazards are present across science disciplines, including biology; chemistry; physics; Earth and space science; engineering; and science, technology, engineering, and mathematics (STEM) instructional settings.

Potential sources of electrical hazard include wall and bench outlets, switches, power supplies, extension cords, electrical leads, damaged plugs, frayed wires, and improperly connected equipment. Exposure to electrical current can result in serious injury, including burns, muscle contractions, loss of consciousness, cardiac effects, or death. For this reason, all electrical activities should be preceded by a hazard analysis and risk assessment, and students should be taught to inspect equipment, keep electrical devices away from water and wet surfaces, use equipment only as directed, report damaged cords or devices immediately, and never handle electrical equipment without teacher authorization.

Hazards

Electrical hazards may be present in science laboratories and STEM instructional spaces even when activities appear low risk. Teachers and students should be aware of potential hazards associated with batteries, power supplies, electrostatic generators, wall outlets, cords, and other electrical equipment. All electrical activities should be preceded by a hazard analysis and risk assessment, and equipment should be used only as intended and under appropriate supervision.

Common electrical hazards include the following:

1. Dry cell batteries. Single dry cell batteries commonly used in middle school science activities are generally low voltage; however, risk increases when multiple batteries are connected, when batteries are short-circuited, or when they are used improperly. Non-rechargeable batteries should never be recharged because they may leak, overheat, rupture, or explode.
   
   
2. Rechargeable batteries. Rechargeable batteries can be reused but may overheat, leak, or fail if short-circuited, damaged, overcharged, or charged with an incompatible charger. Rechargeable batteries should be charged only with manufacturer-approved equipment and should be inspected for damage before use.
   
   
3. Automotive batteries. Automotive batteries and similar high-current batteries can present significant hazards, including electrical shock, burns, acid exposure, and the release of flammable gases. These batteries are not appropriate for lower-level science activities and should be used in high school settings only when justified by the instructional purpose, supported by a documented risk assessment, and supervised by a knowledgeable instructor.
   
   
4. Low-voltage power supplies. Low-voltage power supplies are commonly used as an alternative to batteries and may be appropriate for many classroom circuit activities when used within their rated limits. Students should be instructed not to modify connections, bypass safety features, short-circuit terminals, or use the equipment near water or wet surfaces.
   
   
5. High-voltage power supplies. High-voltage power supplies can produce dangerous currents and voltages and may present serious shock or burn hazards. These devices are generally not appropriate for routine student use in kindergarten through grade twelve laboratories and should be used only by qualified personnel under carefully controlled conditions, if used at all.
   
   
6. Electrostatic machines. Wimshurst machines, Van de Graaff generators, and similar devices can produce high electrostatic potentials. Although the total charge may be limited, these devices can still pose hazards, especially for individuals with certain medical devices or health concerns and when used near flammable materials or sensitive electronic equipment. Electrostatic machines should be operated only by a knowledgeable adult for demonstration purposes and under established safety procedures.
   
   
7. Wall and bench receptacles. Wall and bench outlets, including ground fault circuit interrupter (GFCI)-protected receptacles, can present serious electrical hazards. GFCIs provide important protection but do not eliminate all risk. Students should never insert objects into outlets, touch metal prongs, handle plugs with wet hands, overload outlets, or use damaged cords or plugs. Damaged or malfunctioning receptacles and electrical equipment should be reported immediately and removed from use until inspected or repaired by qualified personnel.

Electrical Safety Practices

All science and STEM instructional activities involving electricity should be preceded by a hazard analysis and risk assessment. Students, educators, and other laboratory occupants should receive instruction on appropriate electrical safety practices before using electrical equipment, batteries, power supplies, electrostatic generators, circuits, or related devices. Safety-related work practices should be appropriate to the nature and level of the electrical hazard and should be used to prevent shock, burns, fire, and other injuries. OSHA identifies safety-related work practices as necessary to prevent injury from direct or indirect contact with energized equipment or circuits.

Electrical equipment should be inspected before use and removed from service if cords are frayed, plugs are bent or damaged, grounding pins are missing, insulation is compromised, or equipment appears unsafe. Students should not remove outlet or switch covers, insert objects into receptacles, touch metal prongs, handle plugs with wet hands, or use electrical equipment near water or wet surfaces. Cords and wires should be arranged to prevent tripping, and access to electrical panels, disconnect switches, and emergency shutoffs must remain clear and unobstructed.

Laboratory occupants should know the location of the master electrical shutoff or disconnect switch, and the location should be clearly marked. Power should be disconnected before equipment is inspected, adjusted, cleaned, or maintained. Routine maintenance, repairs, circuit breaker resets, or work on electrical devices should be performed only by authorized and trained personnel in accordance with district procedures. OSHA’s lockout/tagout standard addresses the control of hazardous energy during servicing and maintenance when unexpected energization or release of stored energy could cause injury.

Students should use only teacher-approved circuits, batteries, power supplies, and electrical devices, and all equipment should be used within its rated limits and intended purpose. Conductive jewelry should be removed when appropriate, tools and equipment should have insulated or nonconductive handles when electrical hazards are present, and flammable chemicals should not be used or stored near electrical equipment. Batteries should be inspected for damage, cracks, corrosion, or leaking before use; damaged batteries should not be used, opened, short-circuited, recharged unless designed for recharging, or stored with terminals touching.

In the event of an electrical shock, fire, or equipment malfunction, the activity should stop immediately, and established emergency procedures should be followed. No one should touch a person who may still be in contact with an energized source. Power should be shut off from a safe location when possible, emergency assistance should be summoned, and first aid or CPR should be provided only when it is safe to do so and by trained personnel. Water should not be used on electrical fires; only the appropriate fire extinguisher should be used by trained individuals, following school and district emergency procedures.