Please note: All interim revisions for this edition available at time of your purchase will be included.

Appliance Leakage-Current Interrupters

UL 943B

1 Scope

1.1 These requirements cover appliance leakage-current interrupters (ALCIs), intended for use only in 2- or 3- wire alternating-current circuits wherein one of the wires is grounded in accordance with the National Electrical Code, ANSI/NFPA 70. They are intended to interrupt the electric circuit to the load when a fault current to ground exceeds some predetermined value that is less than that required to operate the overcurrent protective device of the supply circuit. An ALCI trips when the current to ground reaches a value in the range of 4 - 6 mA.

1.2 These requirements cover 2-wire appliance leakage-current interrupters for use only in cord-connected appliances intended for connection to alternating-current circuits of 250 V or less. An additional ground conductor may be provided. They are not to be provided with a general-purpose outlet receptacle, cord-connector body, or similar devices. Devices complying with these requirements are acceptable for use as components in an end product where the acceptability of the combination is to be determined.

1.3 The acceptability of an appliance leakage-current interrupter in any particular application depends upon its ability to be used continuously under the conditions that prevail in actual service. Accordingly, for a particular application, an appliance leakage-current interrupter may be affected by the requirements for the equipment it is used in, and it may be necessary to additionally evaluate features or performance characteristics that are not specified in this standard.

1.4 This standard does not cover ground-fault circuit-interrupters, which are covered by the Standard for Ground-Fault Circuit-Interrupters, UL 943.