Lab Health and Safety

Require Grounded Plugs on All Electrical Equipment and Install GFI's Where Appropriate

The National Safety Council reports that about 1,000 people are electrocuted each year in the United States. In 2005, a biology professor at Cleveland State University died as the result of an electrical shock in the lab.

James A. Kaufman

OSHA specifies that all equipment in the workplace be grounded to avoid shock and possible electrocution. Removing or breaking off the ground pin is a bad and potentially fatal idea.

Most people are not aware of the danger associated with ungrounded equipment. This danger is compounded when the plug is a two-prong un-polarized type. If inserted backwards, the case of the appliance can be electrically hot. We find many in labs that are 50 to 120 volts hot.

This same problem can be caused by two other circumstances: (1) the electrician wires the receptacle backwards or (2) the appliance manufacturer does not follow the convention. In any of these three cases, if you near a ground, serious or fatal shocks can occur. Make sure that the ripple side of the appliance cord is connected to the wider side of the receptacle.

A ground monitor or circuit analyzer can be used to ensure that the receptacle is correctly wired. An AC-sensor can tell you if the case of the appliance or device is electrically hot or not. A Tension Tester will indicate if the receptacle is holding on to the plug’s prongs with sufficient force to meet electrical code specifications. All three tests should be performed annually on receptacles and electrical equipment in the lab.

The use of Ground Fault Interrupters (GFIs) can provide significant shock protection. They should be installed in any location where the receptacle is within six feet of a ground or water is likely to be present on the floor or surfaces.

Source: Kaufman, James A., Laboratory Safety Guidelines - Expanded Edition, The Laboratory Safety Institute, www.labsafetyinstitute.org.