Keeping your work site safe

Extension cord safety

With the wide use of power tools on construction sites, flexible extension cords often are necessary. Due to the very reasons they are used, (exposed, flexible, and unsecured) they are more susceptible to damage than fixed wiring. Hazards are created when cords, cord connectors, receptacles, and cord- and plug-connected equipment are improperly used and maintained.

You can help keep you and your work site safe with these tips from the Occupational Safety and Health Administration (OSHA) about extension cord safety:

• Provide strain relief - To reduce hazards, flexible cords must connect to devices and to fittings in ways that prevent tension at joints and terminal screws. Flexible cords are finely stranded for flexibility, so straining a cord can cause the strands of one conductor to loosen from under terminal screws and touch another conduct


• Be aware of cord damage - A flexible cord may be damaged by door or window edges, by staples and fastenings, by abrasion from adjacent materials, or simply by aging. If the electrical conductors become exposed, there is a danger of shocks, burns, or fire.


• Use durable cords - The OSHA construction standard requires flexible cords to be rated for hard or extra-hard usage. These ratings are derived from the National Electrical Code, and are required to be indelibly marked approximately every foot along the length of the cord.  Examples of these codes are: S, ST, SO, and STO for hard service, and SJ, SJO, SJT, and SJTO for junior hard service.


• Make sure of proper grounding - Extension cords must be 3-wire type so they may be grounded, and to permit grounding of any tools or equipment connected to them.


• Be careful when using cords in wet conditions - When a cord connector is wet, electric current can leak to the equipment grounding conductor, and to humans who pick up that connector if they provide a path to ground. Such leakage can occur not just on the face of the connector, but at any wetted portion. Limit exposure of connectors and tools to excessive moisture by using watertight or sealable connectors.

Utilizing these tips can help keep your site a safe place to work.