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Avoiding Electrical Hazards in the Lab

By Kenneth Roy

Posted on 2017-02-14

In science, technology, engineering, and math (STEM) labs, teachers and students can be exposed to a number of electrical hazards such as damaged electrical receptacles, missing ground prongs, and faulty electrical equipment. These hazards can result in electric shock, electrocution, fire, and explosions.

Circuit breakers only protect the science lab and school building—not the teachers or students—from these hazards. A ground fault circuit interrupter (GFCI), a device that constantly compares current flowing from the hot wire to the neutral wire in a circuit, can help protect lab occupants from electrical accidents. If the GFCI senses an imbalance in the current, a switch will open and the current will stop flowing in about 1/40 of a second.

To help maintain your GFCI, the circuit breaker must be flipped on and off a couple of times on a monthly basis to prevent the buildup of corrosion that might interfere with the operation of the GFCI. This is especially true in lab environments that contain corrosive fumes. Warn/inform your colleagues before flipping the breaker, in case computers or other technologies are being used during the maintenance.

According to the Occupational Safety and Health Administration’s QuickFacts (see Resources) teachers should follow these better professional practices to avoid electrical hazards in the lab:

1. Make sure manufacturer’s recommendations are followed when using any electrical equipment.

2. The safest lab equipment has either a three-prong plug (including a ground plug) or double insulation.

3. Make sure any electrical receptacle used near a water source (e.g., sinks, aquariums, wave tanks) is GFCI-protected and operational.

4. Do not use extension cords as a substitute for permanent wiring. This can be a fire hazard.

5. Before using any electrical equipment in the lab, visually inspect the power cord and plug to make sure they are in good condition.

6. If you plug more than two pieces of low-demand equipment (e.g., computer, printer) into a standard outlet, use a fused power strip that will shut off if too much power is used.

7. Do not use power strips for high-demand electrical equipment (e.g., microwave oven, power tools) because they can be a fire hazard. Only plug them into a standard outlet.

8. Never disable any electrical safety feature. For example, never break off a ground prong from a three-conductor plug.

9. Never directly touch someone who is being shocked or electrocuted. Although the human body is a poor conductor of electricity, a wet surface and as little as 1/5 Amp can cause serious injury. If possible, turn off the power (pull the plug or trip the circuit breaker), or use an item made of nonconductive material (e.g., wooden broom handle) to pry him or her away from the electrical source. Call 911 immediately.

10. GFCIs do not protect the individuals from line-to-line contact hazards, when a person holds two hot wires or a hot and a neutral wire at the same time. If a student’s fingers were on the metal prongs of a microscope plug when pushing it into an outlet, for example, this would constitute line-to-line contact. At the least, the student would receive a serious shock.

In the end

To find out whether your lab is GFCI-protected, ask the supervisor of school facilities to survey the lab for GFCI protection. Additionally, hardware or electrical stores usually carry GFCI test devices for about $10, which are simple to operate and can test a whole lab within a few minutes.

GFCI protection is required under National Fire Protection Association (NFPA) and OSHA codes and regulations. Science teachers need to work with administration to make sure their labs are up to code. Further, a licensed electrician or building inspector should check for applications of the NFPA and OSHA standards in science labs. See Resources for more information on electrical safety.

Submit questions regarding safety in K–12 to Ken Roy at, or leave him a comment below. Follow Ken Roy on Twitter: @drroysafersci.


Electrical circuit-interrupters—
OSHA QucikFacts—

NSTA resources and safety issue papers
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