UL 248-4

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These requirements cover component electronic co ntrols intended to be factory installed on or in appliances and other utilization equipment rated 60 0 volts or less, used in ordinary dry locations as defined in the National Electrical Code, NFPA 70, and that comply with the requirements for such appliances and equipment.

For a control covered by this standard, it is assumed that no voltage greater than 600 volts above ground will be present in a control, that an isolation transf ormer, if provided, will generally furnish power at a lower potential than the primary voltage, and that the output of the control will not be locat ed in a circuit operating at greater than 600 volts above ground in the end- use equipment. If conditions other than these are provided, consideration shall be given to the need for additional examination and testing.

A control covered by this standard is a single device or a series of separate components with interconnecting wiring employing one or more input power and possibly signal ports, solid-state circuitry, and one or more outpu t switching components to directly control all or a portion of the end-use equipment load. The control may respon d directly or indirectly to ch anges in temperature, humidity, or pressure to affect operation of an appliance, may be an electronic timer, or may electronically store or process information by virtue of a memory system.

A control intended for connection only to a low-voltage circuit of limited power supplied by a primary battery or by a Class 2 transformer where a failure of such a control would cause a risk of fire, electric shock, or injury t o persons to occur in the end-use equipment, is considered to be within the scope of these requirements.