The typical laboratory contains a wide variety of electrically-powered equipment including stirrers, shakers, pumps, hot plates, heaters, power supplies, ovens, and electrophoresis equipment. These and all electrical devices used in the lab setting present a potential danger of injury due to electric shock, fires due to poorly installed or maintained systems and fires due to sparks serving as an ignition source for flammable or combustible materials.
Lab workers can protect themselves from the hazards of electricity by following some basic guidelines. The guidelines include maintaining awareness of the condition of lab equipment, the proper use of lab equipment and safe work practices.
- Learn the location of your electrical panels and shut-off switches so you can quickly disconnect power in the event of an emergency. Be sure to always leave at least a 3-foot clearance around electrical panels for ready access.
- Plan ahead for what steps will be taken in the event of a power loss. Think about potential vapor/gas release from vapor-generating processes or chemical fume hoods if power is lost.
- Conduct a periodic inspection of laboratory electrical equipment to be sure it is in good condition. Remove equipment from service if in poor condition and replace or have it repaired by a qualified repair person.
Electrical outlets should have a grounding connection and accept three-prong plugs. Multiple plug outlet adapters are not allowed.
Power Cords, Power Supplies
- Inspect power cords to be sure they are not frayed or have exposed wiring.
- Carefully place power cords so they don’t come in contact with water or chemicals. Contact with water is a shock hazard. Corrosives and solvents can degrade the cord insulation.
- Do not allow cords to dangle from counters or hoods in such a manner that equipment could be unplugged, fall or cords could be tripped over.
- Do not allow cords to contact hot surfaces to prevent melting insulation.
- Do not lift a piece of electrical equipment by the cord or pull the cord to disconnect from the outlet in order to prevent damage.
- Portable power supplies are commonly used in the lab. These devices are extremely high electrical energy sources and must be used carefully. Never attach an exposed connector such as an alligator clip to a power supply.
- Power cords must have grounding plugs (3 prong) and be properly insulated.
- Extension cords are not allowed in the laboratory for permanent use. The only exception is that electrical power surge protectors (UL listed and available from University General Stores) are allowed only for personal computers and their components.
- No more than two high current draw devices such as ovens and centrifuges should be plugged into the same outlet to prevent an overloaded circuit. Overloading can lead to overheated wires and arcing. This can cause electrical shock injury and fire.
- Fuses and circuit breakers prevent over-heating of wires and other electrical components. This overload protection is useful for equipment that may be left on for a long time such as stirrers, drying ovens, vacuum pumps, Variacs, etc.
- Ground-fault circuit interrupters, or GFCIs, disconnect current if a ground-fault is detected and protect the user from electric shock. GFCI outlets or portable GFCIs are used near sinks and potentially wet locations. Keep electrical equipment (and yourself while you are using electrical equipment) away from water/chemical or their spills unless you are sure the equipment is rated for this type of use.
Electricity and Flammable Materials
- Keep flammable materials away from electrical equipment. The equipment may serve as a source of ignition for flammable or explosive vapors.
- Receptacles providing power for equipment used inside a fume hood should be located outside the hood.
- Make sure that equipment used where flammable vapors may be present is specially rated to not produce sparks. Many household appliances such as hot plates, vacuum cleaners, and drills don’t meet this requirement so they should be used only under very controlled conditions.
- If refrigeration or freezing is needed, flammable materials should only be stored in explosion safe or explosion proof equipment. These do not contain any spark sources such as lights and switches.
- Do not plug heating mantles directly into a 110-volt outlet as they can overheat, leading to fire hazard. They need a variable autotransformer to control the input voltage.
- Be aware that if drying ovens are used to dry organic materials, vapors may accumulate inside the oven and/or escape into the lab atmosphere. Take care to prevent developing explosive mixtures in air by not drying organic materials that can create these conditions.
General Electrical Safety
- Avoid contact with energized electrical circuits.
- Only qualified electrical workers may install, service or repair electrical equipment.
Reference: Prudent Practices in the Laboratory – Handling and Disposal of Chemicals, National Research Council, National Academy Press, Washington, D.C., 1995