Nec 314.25(B) exposed combustible wall

[Jpflex]

where a luminair canopy or pan exceeding installed within combustible material finish exceeding 180 in sqr around the canopy or pan edges, ahall be covered with non combystible material

What exactlt does this mean

Is NEC saying that luminairs and pans must have a void space around it exceeding 180 sq inches if nearby finish ( wall ) is combustible?

In contrast flush mounted services require no such gap greater than 1/4 inch between itself and finish surface

Also do you put calking around the pan to meet this requirement or what material do you use?

Never seen anyone enforce this code?

 

[wwhitney]

What exactlt does this mean

Look at the closed region bounded by the box, the canopy, and any exposed finish material between the two (e.g. a 6" canopy over a 4" box has a exposed ring of finish material, 6" outer diameter, 4" inner diameter). If that exposed finish material includes over 180 in^2 of combustible material, then you have a problem. (For the 6" canopy over a 4" round box, the area would be 9*pi - 4*pi = 15.7 in^2, so it's quite far from the requirement kicking in).

Cheers, Wayne

 

[tortuga]

Also do you put calking around the pan to meet this requirement or what material do you use?

When doing remodel work I use a product called 'hot mud' or 'fix all' a plaster you mix up in a small quantity and drys in about 10 min. When a plaster contractor is on the job I tell them to leave no gaps at all simply mud in all the boxes. I'd rather have a little mud get in the box than a big gap I have to deal with later.

 

[hbiss]

When doing remodel work I use a product called 'hot mud'

Durabond comes in 90, 20, 10 etc that is the drying time. That time is for when you use it at a regular drywall taping thickness which it is used for. If you use it to fill gaps expect to let it dry for several hours or overnight.

We used to use plaster of paris to fill holes and gaps. That stuff sets up real quick.

-Hal

 

[Jpflex]

Durabond comes in 90, 20, 10 etc that is the drying time. That time is for when you use it at a regular drywall taping thickness which it is used for. If you use it to fill gaps expect to let it dry for several hours or overnight.

We used to use plaster of paris to fill holes and gaps. That stuff sets up real quick.

-Hal

This apply only to luminair canopy boxes? I have never seen this cide followed or enforced

The purpose of this code is because lighting equipment are expected to heat surrounding areas?

 

[Jpflex]

Look at the closed region bounded by the box, the canopy, and any exposed finish material between the two (e.g. a 6" canopy over a 4" box has a exposed ring of finish material, 6" outer diameter, 4" inner diameter). If that exposed finish material includes over 180 in^2 of combustible material, then you have a problem. (For the 6" canopy over a 4" round box, the area would be 9*pi - 4*pi = 15.7 in^2, so it's quite far from the requirement kicking in).

Cheers, Wayne

i thought this code was talking about the gap between the luminair pancake or box and adjacent combustible wall finish?

You are saing that the luminair diameter must cover 180 in sq of combustible finish

This seems to be so much work to calculate the outside area and subtract inside luminair box area to find if the total exposed combusible material exceeds 180 in sq. If this is what is being asked for?

 

[wwhitney]

This seems to be so much work to calculate the outside area and subtract inside luminair box area to find if the total exposed combusible material exceeds 180 in sq. If this is what is being asked for?

No really, take the area of the ceiling the canopy covers, subtract from that the area of the box.

And yes, this is what is being asked for.

And yes, 314.25(B) only applies to luminaires canopies or pans.

Cheers, Wayne

 

[Jpflex]

No really, take the area of the ceiling the canopy covers, subtract from that the area of the box.

And yes, this is what is being asked for.

And yes, 314.25(B) only applies to luminaires canopies or pans.

Cheers, Wayne

Another ambiguous written code by nec