Ceiling lite boxes within 3 ' of each other .

[ronball]

Framing inspector just did an inspection and told the general that ceiling lite boxes can't be with 3' of each other.
Only been doing this 28yrs, but never heard of that one. Does it make any difference what type boxes are used,
or this just some bull. 3 pendant boxes with led puc boxes of living room. Help please. 39 unit bld. btw.

 

[ActionDave]

Not anything I've heard of.

 

[Dennis Alwon]

It may have something to do with fire walls unless the fixtures are fire-rated. Ask him/her for an explanation

 

[LarryFine]

Ask for the code article. Ain't no such animal.

 

[tthh]

Dying to hear the inspector's logic on this one.

 

[steve66]

Is it a fire rated ceiling? There are some limits on penetrations for fire rated ceilings.

Might need fire rated fixtures, or might have to put the fire rated mats over the boxes.

TENMAT Fire Rated Light Cover- Techmat Supply - fireproofing.us

1 Hour Fire Rated Dom-shaped Light Cover designed to maintain the integrity of Fire Rated Ceilings when penetrated by recessed fixtures. UL tested.

fireproofing.us

 

[augie47]

If it;'s a fire rated ceiling the following applies:

Clearance between boxes and cutouts in ceiling shall not exceed 1/8 in. The area of openings for boxes shall not aggregate more than 64.7 sq in. per 100 sq ft of ceiling area, with no opening exceeding 12.5 sq in. No box shall be located within 4.5 ft of another box within a common joist cavity.

 

[Johnhall30]

If it;'s a fire rated ceiling the following applies:

Clearance between boxes and cutouts in ceiling shall not exceed 1/8 in. The area of openings for boxes shall not aggregate more than 64.7 sq in. per 100 sq ft of ceiling area, with no opening exceeding 12.5 sq in. No box shall be located within 4.5 ft of another box within a common joist cavity.

Where is this from? The IBC has a different set of rules

 

[steve66]

Where is this from? The IBC has a different set of rules

I thought it came from the UL Fire Rated Assemblies Directory. So there could be different assemblies with different requirements.

But that might be for commercial construction. Residential might be different.

For example: Here are some USG assemblies:

https://www.usg.com/content/usgcom/en/design-studio/floor-ceiling-assemblies.html?facets={%22k%22:%22FireRating_facet_pim%22,%22v%22:[%221%20hours%22]}

 

[PaulMmn]

If it;'s a fire rated ceiling the following applies:

Clearance between boxes and cutouts in ceiling shall not exceed 1/8 in. The area of openings for boxes shall not aggregate more than 64.7 sq in. per 100 sq ft of ceiling area, with no opening exceeding 12.5 sq in. No box shall be located within 4.5 ft of another box within a common joist cavity.

I think the "common joist cavity" is the key here.... but that's IFF it's a fire-rated ceiling! Even so, the inspector needs a new tape measure!

 

[JoeStillman]

In a 39-unit, multi-story building, the floor/ceiling assembly (including the sheet rock, joist, and flooring) is fire rated. The rating doesn't come from any one element. It's the assembly that has a UL rating. The UL specs for that particular assembly will dictate the number and size of penetrations. Are they solid joists or trusses? Hard to imagine how the "common joist cavity" matters if it's a truss joist.