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Which of the fluorescent ballasts are required to have thermal protection?
2014-03-26 12:03:58
The ballast of a fluorescent luminaire installed indoors, including a replacement
fluorescent ballast for this type of luminaire
A simple reactance ballast in a fluorescent luminaire with straight tubular lamps
The special provisions for electric-discharge lighting systems of 1,000V or less can be found in Part XII of Art. 410. As noted in 410.130(E), "The ballast of a fluorescent luminaire installed indoors shall have integral thermal protection. Replacement ballasts shall also have thermal protection integral with the ballast."
In accordance with the National Electrical Code (NEC), all canned and potted
electronic fluorescent ballasts require built-in Class P Thermal Protection. This protection is provided by a switching device that shuts down the circuit if the ballast temperature rises to 105°C or greater.
The switching device will reset so the ballast will resume operation once the ballast cools down. This off-again, on-again cycling will continue until the cause of the excess heat is eliminated.
A simple reactance ballast in a fluorescent luminaire with straight tubular lamps, a ballast in a fluorescent exit luminaire, and a ballast in a fluorescent luminaire used for egress lighting and energized only during a failure of the normal supply are not required to have thermal protection.
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