UL496 vs. UL1598 Lampholders
UL496 vs. UL1598 Lampholders
The ratings of a lampholder are determined by certification to UL 496, Edison Base Lampholders. The rating for a mogul base is 1500 watts and a medium base is 660 watts. These ratings are tied back to the era of using a resistive coil heater in an edison base lampholder.
The ratings for a luminiare are determined by UL1598 temperature tests or construction requirements. During a UL1598 temperature test, UL monitors temperatures on the lampholder leads, Wiring in the junction box and temperatures of combustible material - wood/drywall. Temperature limits for wiring in j-box is 90C for residential use, due to NM cable temperature rating. Temperature limit for combustible material is 90C. Temperature limits for lampholder leads will be determined during test and feedback provided to luminare manufacturer to allow him to purchase the correct lampholder with the correct lampholder leads.
In the original post, the luminaire used probably tested and the 65 watt lamp was the maximum wattage which did not exceed the 90C limit of the combustible material or j-box.
Overlamping of a luminaire can result in NM insulation becoming brittle, cracking and falling off wire. Also, drywall will dry out and crumble after prolong exposure to high temperatures.
UL496 vs. UL1598 Lampholders
The ratings of a lampholder are determined by certification to UL 496, Edison Base Lampholders. The rating for a mogul base is 1500 watts and a medium base is 660 watts. These ratings are tied back to the era of using a resistive coil heater in an edison base lampholder.
The ratings for a luminiare are determined by UL1598 temperature tests or construction requirements. During a UL1598 temperature test, UL monitors temperatures on the lampholder leads, Wiring in the junction box and temperatures of combustible material - wood/drywall. Temperature limits for wiring in j-box is 90C for residential use, due to NM cable temperature rating. Temperature limit for combustible material is 90C. Temperature limits for lampholder leads will be determined during test and feedback provided to luminare manufacturer to allow him to purchase the correct lampholder with the correct lampholder leads.
In the original post, the luminaire used probably tested and the 65 watt lamp was the maximum wattage which did not exceed the 90C limit of the combustible material or j-box.
Overlamping of a luminaire can result in NM insulation becoming brittle, cracking and falling off wire. Also, drywall will dry out and crumble after prolong exposure to high temperatures.