Extension cords are defined as a length of factory-assembled flexible cord with an attachment plug or current tap as a line fitting and with a cord connector as a load fitting.
Extension cords (see figure 1) are used for extending the electricity supply of an electrical outlet or receptacle to a portable corded appliance or device, such as a toaster, a lamp, a television, or a leaf blower. The rule applies to extension cords that are equipped with National Electrical Manufacturer Association (“NEMA”) 1-15, 5-15 and 5-20 fittings (see figure 2), and that are intended for indoor use only, or for both indoor and outdoor use. The Commission refers to cords intended for indoor use only as “indoor cords” and to cords intended for both indoor and outdoor use as “outdoor cords.” The term “extension cord” does not include detachable power supply cords, appliance cords, power strips and taps, and adaptor cords supplied with outdoor tools and yard equipment (see figure 3). (Extension cords have receptacles or outlets molded into the cord itself, whereas power strips and taps have flexible cord but receptacles or outlets are not molded into the cord itself. Power strips and taps covered by a voluntary industry consensus, the Standard for Current Taps and Adapters, UL 498A)
Figure 1

Figure 2

Figure 3

All products within the scope of the rule are covered by UL 817.
The following table provides a non-exhaustive list of examples of extension cords that fall within and outside the scope of the rule.
In Scope: Household extension cords, factory-assembled,
120 volts AC, including:
- Indoor or general-use extension cords (also known as cord sets), including seasonal indoor extension cords (which are designed to be used for only limited time period)
- Outdoor extension cords (also known as cord sets)
Out of Scope:
- Detachable power cords, either with appliance or other nonstandard plugs (e.g., accompanying electronic or other electrically powered items), or with fittings of different configurations (e.g., a clothes washer replacement cord with a plug at one end and individual wire terminals at the other end)
- Unassembled components, such as flexible cord or fittings, which may be assembled into extension cords or installed in permanent branch circuit wiring systems
- Cord sets intended for use with non-branch-circuit household current, i.e., greater or less than nominal 120 volts AC (e.g., for use with 220 volt appliances, or for 15-50 ampere/125-–250-volt recreational vehicles)
- Power strips, power taps, and surge protectors