# How close can light fixtures be to fire sprinkler heads?

I'm planning to add several rows of fluorescent light fixtures in my garage, which has partly recessed fire sprinkler heads. Does code specify how close fixtures can be to the sprinklers?

Common sense says the lights should not block the sprinklers, but I'm not sure how far that really would mean. The light fixtures I would like to use are about 4" tall.

Finally, if surface mounting lights nearby is an issue with code, what about recessed lights?

I was able to track down the relevant code document for residential sprinker installations - it's 2010 NFPA 13D, section 8.2.5.2, and it's actually viewable online for free if you register your email address. There is a different code for commercial buildings. For this issue at least, the residential requirements are much more strict.

The residential code says pendant sprinklers must be at least 3 ft from obstructions such as ceiling fans and lights (as measured from their centers), or you can use this table which relates A) the distance from the sprinkler to the near edge of the obstruction and B) height of the sprinkler's deflector above the bottom of the obstruction.

``````ceiling----------------------------------------------
|                  *               *
sprinkler  -+-      ---        *  obstruction  *
B         *               *
---        *****************

|<----    A   ---->|

---------------    --------------
Distance A (ft)    Maximum B (in)
---------------    --------------
up to 1.5          0
1.5 - 3            1
3 - 4              3
4 - 4.5            5
4.5 - 6            7
``````

The sprinklers spray at an angle of approximately 45 degrees. So of your light fixture is 4 inches deep, then you should keep them at least 4 inches away from the sprinkler heads.

Also, I know that the light fixtures in our office are immediately adjacent to the ceiling tiles that have the sprinkler heads in the center and the ceiling tiles are 24 inches. So 12 inches seea to be acceptable.

• I thought 45 degrees sounded pretty reasonable, but turns out the code is much more strict when the lights are not recessed.
– JayL
Commented Aug 18, 2011 at 6:40
• Ok, that makes sense. I saw sprinklers for residential installation at my local hardware store the other day and I was stuck by how flat the fan plate thing that disperses the water was compared to the ones at my office. I know from first-hand experience that the ones at work spray at a 45 degree angle, but the ones I saw would definitely spray almost horizontal. I'm glad you found the code. Good answer! Commented Aug 19, 2011 at 3:54

I'm looking at our recessed-head FSS, and I see one head cover less than 6 inches from the nearest fluorescent light. This is a drop ceiling, though (standard office space construction), so the cover and the bottom of the light pan are at the same level, so there's virtually no chance of the sprayer hitting anything energized.

• I noticed the same where I work, but in my case it would be a real hassle to do recessed lights.
– JayL
Commented Aug 18, 2011 at 6:38

In an NFPA 13 Light Hazard Occupancy, there is an exception that states only structural members are required to be considered when determining an obstruction. Of course this presumes that you are NOT blocking the entire fire sprinkler discharge with the light, and there is the requirement that an installation must meet with the code official's approval. Should he perceive that it is a Life Safety issue, then it is likely you will not garner an occupancy permit. That last broadly referenced statement is found in both the NFPA standard and in the IFC. More modern NFPA 13 editions also have included information on Shadow Areas that may be helpful. Please consult with an engineer or licensed design-build contractor for additional information in your area for specific information applicable to your building and fire codes.