Addressing Electrical Hazards in the Lab

Accidents in the lab involving electricity can produce fire, smoke, electrocutions, and explosions. According to the Occupational Safety and Health Administration (OSHA), “electrical equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees.” This blog post describes the steps teachers must take to prevent such hazards from arising in their science classrooms and laboratories.

Preventing electric shock and electrocution

Unfortunately, many people believe circuit breakers protect lab occupants. In fact, circuit breakers only protect the science labs and building, not the teachers or students. Breakers are designed to prevent electrical fires by shutting off the electrical flow if too much electricity tries to move through the circuit’s wires. An excessive amount of electricity coupled with resistance may lead to a fire.

The human body is a poor conductor of electricity. Even so, if a person were to come in contact with a wet surface and an electric current of as little as one-fifth of an amp, then that person could receive a harmful shock. Installing a ground-fault circuit interrupter (GFCI) in the lab can protect students and teachers from electric shock and electrocution. This device constantly compares current flowing from the hot wire to the neutral wire. If the GFCI senses an imbalance of approximately 5 milliamps in the current flow, the current will stop flowing in less than a second.

However, there are two safety issues with GFCIs that need to be addressed. First of all, if these electrical devices are not maintained, they may corrode and not function properly. Preventative maintenance can avoid this situation. This can easily be done by flipping the breaker several times every month or two. Inform the school of this maintenance to ensure that computers or other technologies are not being used when flipping the breaker.

Second, the GFCI does not protect the individuals from a line-to-line contact hazard, which happens when a person holds two hot wires or a hot and a neutral wire at the same time. This could happen if a student has his or her fingers on the metal prongs of the plug when pushing it into the wall receptacle. Students and teachers need to be made aware of this danger in safety training workshops at the beginning of the school year before doing work in the laboratory.

Meeting legal safety standards

There are a number of electrical safety protocols that need to be addressed. According to the OSHA, potential exposures to electrical hazards may result from faulty electrical equipment/instrumentation or wiring, damaged receptacles and connectors, or unsafe work practices. OSHA suggests the following best practices to avoid such hazards:

• Always follow manufacturer’s recommendations for using electrical equipment. Do not use electrical equipment to perform a task for which it is not designed.
• Most equipment includes either a three-pronged plug or double insulation. Equipment without these features is less safe, but may meet electrical codes. You will not be protected from electric shock unless you are using a three-pronged plug that is plugged into a three-prong outlet.
• If you plug more than two pieces of low demand equipment into a standard outlet, use a fused power strip that will shut off if too much power is used.
• Make sure that any outlet near a sink or other water source is GFCI protected. If you have a GFCI, periodically test it by plugging something into it and pushing the “test” button. Once the equipment shuts off, just turn it (the GFCI or the equipment?) back on.
• Above all, do not disable any electrical safety feature such as removing a ground prong on a three-prong plug.
• Before turning equipment on, check that all power cords are in good condition.
• Do not use extension cords as a substitute for permanent wiring.
• If you see a person being electrocuted, do not touch the person. Turn off the power (pull the plug or trip the circuit breaker), or use an item made of non-conductive material (e.g., wooden broom handle) to pry the person away from the contact. Call 911 immediately.


Teachers and their supervisors involved with renovations or new science laboratory facilities need to ensure that such electrical protection is provided. Existing laboratory facilities should also have such protection for teachers and students. If concerned about electrical standards and protocols being met, contact your building administrator and request an electrical inspection.

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

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2 Responses to Addressing Electrical Hazards in the Lab

  1. Jane Jackson says:

    The GFCI test instructions are clear as mud. In an attempt to understand the TEST PROCEDURE, IN MORE DETAIL, I quote from a Leviton GFCI instruction card.
    “Like a fire extinguisher … your GFCI outlet should be checked every month ….
    1. Push black TEST button. Red RESET button should pop out from inner surface. This should result in power being OFF at all outlets protected by the GFCI. Verify by plugging a test lamp into every such outlet. …
    2. If the GFCI tests okay, restore power by pushing the RESET button back in. THE RESET BUTTON MUST BE PUSHED FIRMLY AND FULLY INTO PLACE UNTIL IT LOCKS AND REMAINS DEPRESSED. … Test lamp should again light. …
    3. IF GFCI TRIPS BY ITSELF at any time after installation, reset and perform test procedures 1 and 2 above.”
    Call a qualified electrician if any step fails. For example, if
    * RESET button does not pop out (in step 1), or
    * RESET button doesn’t lock into place and remain depressed (in step 2).

  2. Dr. Ken says:

    Dr. Ken comments on Jane Jackson’s statement relative to Leviton GFCI instruction card:
    Jane – thanks for that information on the testing requirement for Leviton GFCI equipment. Unfortunately, this is all over the place. I have seen it before each use, once a week, once a month, once every 3 months, once every several years and more.
    For exmaple, check out what “Requesting Ground Fault Circuit Interrupter Information” ——-
    Section 1926.404(b)(1) does not reguire GFCIs to be tested. However, 1926.20(b)(2) does require the frequent and regular inspections of equipment. The instructions included with the devices indicate that they should be tested monthly. If an employer can demonstrate, for example, by means of logs or procedures, that he or she tests GFCIs monthly and promptly replaces those found defective, then a serious citation may not be appropriate for defective GFCIs found upon inspection, provided the faulty devices are replaced promptly.
    The OSHA response goes further by noting “Electrical/Electronic Technical Note 91-1.”
    Please note – this response is several decades old but still listed. I could not find any updates. If any one does, please share.
    The bottom-line – usually OSHA supports what the manufacturer states as the recommended standard operating procedure as was share by Jane Jackson for this specific brand of GFCI.
    Thanks again – great get!!!
    Dr. Ken

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