UL 6500 - SECOND EDITION

(Sub) CLAUSE/ANNEX NUMBER:

14.5.3

(Sub) CLAUSE/ANNEX HEADING:

PTC-S Thermistors

OTHER RELEVANT (Sub) CLAUSES/ANNEXES (as applicable):

Clause 11.2

DESCRIPTION OF ISSUE:

Is a thermistor required to be UL or CB Certified when used in series with a degaussing coil?

APPLICATION GUIDELINE:

If a thermistor is not UL or CB Certified, it must be shown that the thermistor is not used to prevent an appartatus from becoming unsafe. This is accomplished by conducting the fault test in clause 11.2. The fault test conducted is the short-circuiting of the thermistor since it has not been shown to be reliable by UL or CB Certification.

RATIONALE:

A UL or CB thermistor is required to be UL or CB Certified only when failure (short-circuiting) of the thermistor results in a fire hazard. Conducting the fault test in clause 11.2 will demonstrate if a fire hazard exists.

OTHER:

None.

SEE RELATED PAG:

None.