Surface mount fixtures/ wood ceiling

[kwired]

That is a huge gap-- 180 sq. in. How did they come up with that?

No kidding, I come up with about 15 inch diameter circle

 

[electricalist]

Mr.Dennis I haven't seen the fixture in question, I was only surface mount fixtures have it.
I wanna think that most any ull listed fixture would have by design a way to enclose the wires from the outside and when removed gives access to either a new or old work box ,that is flush with surface. If its uneven wood the a cut in light box gives coverage.

 

[kwired]

The foil backed insulation on a surface mount fixture ?

I think the primary purpose of that foil backed insulation is to help reduce heat levels in the outlet box, but I am not convinced it is all that successful at doing it.

 

[electricalist]

I think the primary purpose of that foil backed insulation is to help reduce heat levels in the outlet box, but I am not convinced it is all that successful at doing it.

I agree I have removed lights that look like they could one day be a problem, but who knows someone probably put 100 watt bulbs

 

[kwired]

I agree I have removed lights that look like they could one day be a problem, but who knows someone probably put 100 watt bulbs

With disappearing incandescent bulbs in recent years this is a problem that will sort of just go away on its own.

 

[don_resqcapt19]

That is a huge gap-- 180 sq. in. How did they come up with that?

18-69 Log #1594 NEC-P18 Final Action: Accept
(410.23)
________________________________________________________________
Submitter: Edward Joseph, Underwriters Laboratories Inc.
Recommendation: Revise text to read as follows:
410.23 Covering of Combustible Material at Outlet Boxes. Any combustible wall or ceiling finish exposed between the edge of a luminaire
canopy or pan and an outlet box, having a surface area of 1160 mm2 (180 in2) or more, shall be covered with noncombustible material.

Substantiation: This proposed revision to Section 410.23 aligns the requirements in the NEC and ANSI/UL1598 for ?listed? luminaires and serves
to further support Section 410.6 which requires the installation of ?listed? luminaires.
Questions have been raised by inspection authorities concerning Section 410.23 as to whether or not there is a need to additionally cover combustible mounting surfaces as defined within in the Article, when installing a ?listed? ceiling mounted or wall mounted canopy style luminaire that does not have a back-plate or back-cover.

Based on explanatory notes in 2008 NEC handbook, Section 410.23 was written to address overheating of combustible surfaces. The note states the following: ? Luminaires must be designed and installed not only to prevent overheating of conductors but to prevent overheating of adjacent combustible wall or ceiling finishes. Hence, it is required that any combustible finish between the edge of a luminaire canopy and an outlet box be covered with a noncombustible material or luminaire accessory.

See 314.20 for the requirements covering combustible finishes. Where luminaires are not directly mounted on outlet boxes, suitable outlet box covers are required.?

Listed luminaires are evaluated to the requirements of the Standard for Luminaires, ANSI/ UL1598. Based on requirements in the ANSI/UL 598
standard, ?listed? canopy style surface or ceiling mounted luminaires do not require a back-plate or back-cover provided the total area of the surface being covered by the canopy is less than 1160 mm2 (180 in2). In addition, these ?listed? canopy style luminaires are evaluated based on requirements in the standard to ensure that temperatures on wall or ceiling surfaces on which the luminaire is mounted do not exceed 90 degrees centigrade. This 90 degrees centigrade limit, is the limit that both the luminaire standard and the NEC assigns for continuous heating of combustible materials. These requirements have been in effect for ?listed? luminaires for several decades. In summary, the requirements for ?listed? luminaires fulfills the requirement of Section 410.23 and therefore, does not warrant the need for additional protection of a combustible mounting surface beyond what the ?listed? luminaire provides.

This proposed revision to Section 410.23 will provide the
needed clarification.
Panel Meeting Action: Accept
Number Eligible to Vote: 11
Ballot Results: Affirmative: 11
________________________________________________________________

 

[Dennis Alwon]

Thanks Don.... I still don't understand why the 180 sq. in. My thinking is that if there is heat where the bulbs are located then that will be less than the 180 sq. in however most ceiling mount units have insulation that would be sufficient to cover this.

 

[kwired]

I kind of think luminaire listing kind of already covers this issue and the change in NEC maybe wasn't all that necessary.

How often do you run into a canopy that is larger then 15 inches diameter? If you do it probably has a back plate of some sort.

I have noticed this more with wall luminaires - especially the types used in bathrooms over the vanity. They are usually rectangular or semi-rectangular but likely close to or over 180 square inches and all of them that large do seem to have a back panel that mounts to the wall/outlet box first then the rest of the fixture body.

 

[ActionDave]

......
How often do you run into a canopy that is larger then 15 inches diameter?.......

Not so much not very long ago, but more and more since California started in with their energy codes and the Ban the Bulb legislation went into phase three.