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The requirements for UL 1434 apply to discrete thermistor-type devices constructed of ceramic or polymeric semiconductor material.

These thermistors are intended for use as:

• Self-limiting devices such as heaters;
• Control devices such as current limiters and inrush-current limiters; or
• Sensing devices.

These requirements apply to positive temperature coefficient (PTC) and negative temperature coefficient (NTC) type devices.

Control devices, such as current limiters are not intended to replace current interrupting devices such as fuses, but are intended to provide a level of overcurrent protection complying with the end-use equipment requirements.

These requirements do not apply to heating cables, such as self-regulating pipe heating cable, that are constructed with thermistor-type material.

A product that contains features, characteristics, components, materials, or systems new or different from those covered by the requirements in this standard, and that involves a risk of fire or of electric shock or injury to persons shall be evaluated using appropriate additional component and end-product requirements to maintain the level of safety as originally anticipated by the intent of this standard. A product whose features, characteristics, components, materials, or systems conflict with specific requirements or provisions of this standard does not comply with this standard. Revision of requirements shall be proposed and adopted in conformance with the methods employed for development, revision, and implementation of this standard.