Extension cords provide a convenient method of bringing AC power to a device that is not located near a power source. They are also used as temporary power sources. As such, extension cords are heavily used here on campus. They are also often involved in electrical code and safety violations.
Improper use of extension cords can lead to shock hazards. In addition, use of an undersized extension cord results in an overheated cord and insufficient voltage delivered to the device, thus causing device or cord failure and a fire hazard. Extension cords also can be trip and fall hazards if they are placed in a walkway.
The U.S. Consumer Product Safety Commission (CPSC) estimates that each year, about 4,000 injuries associated with electric extension cords are treated in hospital emergency rooms. About half the injuries involve fractures, lacerations, contusions, or sprains from people tripping over extension cords. In addition, CPSC also estimates that about 3,300 residential fires originate in extension cords each year, killing fifty people and injuring about 270 others. The most frequent causes of such fires are short circuits, overloading, damage, and/or misuse of extension cords.
Below are some recommendations the Office of Environmental Health and Safety has for extension cord use on campus and at home:
- Extension cords must be approved by the Nationally Recognized Testing Laboratories and properly maintained with no exposed live parts, exposed ungrounded metal parts, damage, or splices.
- Extension cords must be made of a heavy duty or extra-heavy duty rated cable and must be a continuous length. A spliced cord is never permitted.
- Around construction sites, in damp areas, or in an area where a person may be in direct contact with a solidly grounded conductive object such as working in a wash bay, extension cords must be protected by a ground fault circuit interrupter (GFCI). The GFCI can consist of a special circuit breaker, a GFCI outlet, or an extension cord with a built-in GFCI.
- Extension cords should be of sufficient current-carrying capacity to power the device. An undersized cord is a fire hazard.
- Extension cords must be three-conductor (grounded) even if the device has a two-conductor cord. Never use two-conductor extension cords at UT. (Equipment grounding conductors that are part of flexible cords or used with fixture wires shall not be smaller than 18 AWG copper and not smaller than the circuit conductors.)
- Cord repair is not encouraged. In the event it becomes necessary; only qualified personnel may make repairs of extension cords.
There are very few acceptable combinations of extension cords and devices. Some acceptable combinations are:
- Extension cord to device (electrical equipment)
- Power strip to device
- Surge protector (with cord) to device
- Direct surge protector to extension cord to device
- Direct surge protector to power strip to device
For questions on a particular application of extension cord or power strip use, contact the Office of Environmental Health and Safety, the Facilities Services Electric Shop, or review either the Extension Cord Safety Guidelines or the Electrical Safety Policy # GS 50 on our website.