Why can't a hanging fluorescent be surface mounted?

[wesalexleft]

Does anyone know why the instructions say not to surface mount fluorescent shop lights and why this can't be done? I have six 48" T-8 fluorescent shop lights I'm getting ready to install, but instructions say no surface mounting. Headroom is an "almost" issue plus I really don't like the look of those little chains. I'd like to surface mount to the 1/4" plywood ceiling if possible. If it's a heat issue, I can put some 1" or so spacers, but I'd prefer not having the fixtures hanging by 6" of chain. As info, the lights are a Lowe's special of the Utilitech 48" T-8 plug in shop lights with two bulbs per fixture.

Thanks!

 

[Frank The Plumber]

The transformers make a lot of heat and the dang things start your shop on fire for one. I would not mount one direct no matter what.

 

[RobertMo1988]

I have (4) 4ft. T-8 fluorescent fixtures in my garage, granted i am not in there all day but I have had them on for 4-6 hours with no problem. I feel as if the t8s run way cooler(temp) than the t12s. Personally I think you'd be alright but I have no explanation as why they say not to ceiling/surface mount them.

 

[Charles (in GA)]

It depends on the ballast, and the design of the fixture. If the instructions say to not surface mount, they will tell you how much space you have to have. The heat from the ballast is the issue, most likely not the bulb heat. Some fixtures are better designed and acceptable to surface mount. They probably cost more, but its the old "you get what you pay for" addage. If you are not happy with them, I would return them and find something that can be legally (and thus safely) surface mounted.

Charles

 

[fitz11]

I have mine surface mounted (4 bulb t12 fixtures). If the ballast makes enough heat to heat the metal of the fixture to the point it actually ignites the plywood its a defective unit.

 

[wesalexleft]

I suspected some sort of heat output would be the reason. I may try a rigid down rod to mount them which would keep them secure and still provide some airspace between the fixture and ceiling. The chains have a 10" drop and the fixture itself is another3". That's a total of 13" lost on a garage ceiling thats just under 8' now. That's too low. I can't imagine it putting off enough heat to require more than a couple inches of airspace. Thoughts? I'm thinking 3" or so of space would be more than enough to allow circulation. My 6 burner gas grill requires 12" of clearance on the sides and rear and it's putting out 40,000 BTU with an open flame.

 

[StaggeringGoat]

If the ballast makes enough heat to heat the metal of the fixture to the point it actually ignites the plywood its a defective unit.

I would tend to agree, but maybe that's why they say that...what happens when you do get a defective unit? Bonfire......

 

[aandpdan]

This might be part of it. Maybe the manufacturer is too lazy to specify as to what to mount them to.

NEC 410.76 Luminaire (Fixture) Mounting.

(B) Combustible Low-Density Cellulose Fiberboard.
Where a surface-mounted luminaire (fixture) containing a ballast is to be installed on combustible low-density cellulose fiberboard, it shall be listed for this condition or shall
be spaced not less than 38 mm (11⁄2 in.) from the surface of the fiberboard. Where such luminaires (fixtures) are partially or wholly recessed, the provisions of 410.64 through 410.72 shall apply.
FPN: Combustible low-density cellulose fiberboard includes sheets, panels, and tiles that have a density of 320 kg/m3 (20 lb/ft3) or less and that are formed of bonded plant fiber material but does not include solid or laminated wood or fiberboard
that has a density in excess of 320 kg/m3 (20 lb/ft3) or is a material that has been integrally treated with fireretarding chemicals to the degree that the flame spread in any plane of the material will not exceed 25, determined in accordance with tests for surface burning characteristics of building materials. See ANSI/ASTM E84-1997, Test Method for Surface Burning Characteristics of Building Materials.

 

[Falcon67]

I used 4' T8 shop lights in the old shop. On each end, I drilled a 1/8" hole through the back and used 2" deck screws and bitty 1x2 spacer blocks on each end to space the lights away from the joists. Just in case.

 

[I void warranties]

I would tend to agree, but maybe that's why they say that...what happens when you do get a defective unit? Bonfire......

i to believe that's the reason, ever see a t12 ballast fail without blowing its circuit protection? holy

 

[daveroy]

Guys, I think you all have the heat issue correct. But I don't really believe it is a fire hazard so much as a 'life of the unit' factor. When you surface mount it, it will run hotter. Thus shortening the life of the components.
JMHO

P.S. Mine are mounted on the shortest chains I could still get in place with my hand! Bout 1.25"

 

[Frank The Plumber]

These are the $12 or there about fixture I think. If you want to flush mount them you may need to buy a better one. The bulbs cost more than the unit if I recall.

 

[motocapt]

Noob to the board, greetings. I've had surface mounted lights in my garage for 13 years now. If your garage is finished with 5/8" drywall, you have a pretty good insulator against heat if a ballast goes bad.

 

[Gary S]

i to believe that's the reason, ever see a t12 ballast fail without blowing its circuit protection? holy

Yes, but he has T8s, and the new T8s don't use a ballast transformer anymore. That is yesterday's technology. Today we use T8 lamps and electronic ballasts because they don't eat up wasted power generating heat.

 

[ptschram]

I had one that was not surface mounted that didn't catch fire, but it was only due to my being present.

I woke up one morning, turned the light on over my desk, hopped in the shower. By the time I got out of the shower,my condo was filled with smoke. It was only by dumb luck that I got the room aired out before the entire building's smoke alarms went off. Heaven help me had the sprinklers discharged.

As my shop is in a barn more than 100 years old, all of the lights are hung from the ceiling with plenty of airflow around them.

And, yes, the goo that cooks out of the ballasts is a mess and smells to high Heaven.

edit-solid state ballasts (er, aren't they all solid state? perhaps referring to them as something other than just a potted transformer would be a better way to describe them)

 

[Gary S]

And, yes, the goo that cooks out of the ballasts is a mess and smells to high Heaven.

edit-solid state ballasts (er, aren't they all solid state? perhaps referring to them as something other than just a potted transformer would be a better way to describe them)

Old T12 fixtures had ballast transformers. Transformers are wire windings with that black goo in them.
Today's electronic ballasts are a tiny electronic circuit boards much like the circuit board in your cellphone in your pocket. (electronics today is solid state). There is no transformer to burn up inside these new fixtures, and the solid state circuit board ballast produces almost no heat which is why it is more energy efficient.

Now you know why new fixtures weigh almost nothing too.

 

[ptschram]

Old T12 fixtures had ballast transformers. Transformers are wire windings with that black goo in them.
Today's electronic ballasts are a tiny electronic circuit boards much like the circuit board in your cellphone in your pocket. (electronics today is solid state). There is no transformer to burn up inside these new fixtures, and the solid state circuit board ballast produces almost no heat which is why it is more energy efficient.

Now you know why new fixtures weigh almost nothing too.

Solid state used to mean the absence of tubes, hence, they are all solid state. They may not have linear power supplies, replaced with switching power supplies (which are FAR more EFI polluting), but they are solid state-OK, maybe those with "Starters" could have been referred to as other than solid state,but those haven't been in production in years.

 

[Norcal]

I had one that was not surface mounted that didn't catch fire, but it was only due to my being present.

I woke up one morning, turned the light on over my desk, hopped in the shower. By the time I got out of the shower,my condo was filled with smoke. It was only by dumb luck that I got the room aired out before the entire building's smoke alarms went off. Heaven help me had the sprinklers discharged.

Sprinklers are activated by heat & do not all go off at once, that is a Hollywood misconception,the water in the system is nasty due to the primary material being used for fire sprinklers is black iron pipe.


NEC 110.3(B) does require manufacturers instructions be followed, so if the instructions are part of the listing, in order to not be a hack they must be followed.

 

[Gary S]

Solid state used to mean the absence of tubes, hence, they are all solid state. They may not have linear power supplies, replaced with switching power supplies (which are FAR more EFI polluting), but they are solid state-OK, maybe those with "Starters" could have been referred to as other than solid state,but those haven't been in production in years.

Solid state still means using semiconductors instead of vacuum tubes. That never changed.
But, transformers were never solid state and never will be. Every old florescent light I've disassembled that had the ballast transformer, had absolutely no electronics in it, so it cannot be called solid state.
The newer energy efficient ones I've disassembled have only an electronic circuit board and no transformer.
I've never found both in the same fixture.

The solid state board replaced the transformer and does the same function of stepping up the line voltage to a level to fire and operate the lamps.

 

[ptschram]

Sprinklers are activated by heat & do not all go off at once, that is a Hollywood misconception,the water in the system is nasty due to the primary material being used for fire sprinklers is black iron pipe.


NEC 110.3(B) does require manufacturers instructions be followed, so if the instructions are part of the listing, in order to not be a hack they must be followed.

Had I not been present, I am certain the papers on my desk would have ignited form the hot goo (or potting material) dripping on them, thus generating enough heat to discharge the sprinklers in my office.

 

[ptschram]

Solid state still means using semiconductors instead of vacuum tubes. That never changed.
But, transformers were never solid state and never will be. Every old florescent light I've disassembled that had the ballast transformer, had absolutely no electronics in it, so it cannot be called solid state.
The newer energy efficient ones I've disassembled have only an electronic circuit board and no transformer.
I've never found both in the same fixture.

The solid state board replaced the transformer and does the same function of stepping up the line voltage to a level to fire and operate the lamps.

Semantics, semantics. And, I already addressed the absence of vacuum tubes. As early fluorescent fixtures used neon bulbs as starters, they by definition had vacuum tubes and were not solid state, thus, I stand by my statement that they could be referred to as being solid state. edit-I could be wrong on this as I haven't seen one in years that I could tear apart, the ones I have now are needed for the lights in the living room!

Yes, I'm old enough to have built circuits using tubes.

 

[dittle fart around]

Open up the fixture if the ballast is small and light and says "electronic ballast" on it don't worry. The ballast won't heat up any more than the lights will. An older fixture with t-12 bulbs probably has a ballast with a transformer inside. It will weigh a lot compared to the t-8 electronic ballast. Most fixtures have little bumps on the back so there will be a small amount of air space between the fixture and the drywall.

 

[gorilla]

I just dealt with the same problem Your having, My solution was to return the no flush mount fixtures and spend 2X for fixtures that allowed flush mounting. For the chump change difference it's not worth taking a chance on premature ballast failure or a fire.

 

[wesalexleft]

Okay, so here was my final comprimise. I had some 1.5" diameter PVC laying around. I cut it into 2" lengths at the miter saw and fastened the lights to the ceiling with the screws going inside the 2" tubing. the PVC white like the lights and ceiling, so it blends very well, and now the lights are not "swinging" from chain. I'll try to get a picture up at some point. They actually turned out looking great. The T-8 ballasts put off almost no heat. I've let them run for 48 hours to "season" the bulbs and ballasts and the heat is along the lines of a laptop charging block as far as warmth.

 

[wesalexleft]

Here was my quick and easy solution. Instead of the chains hanging down, I disassembled the fixture (three screws...no big deal). I had some PVC tubing scrap, so I cut it into 2" sections and used them as spacers. Blended in well, and looks great.

The first picture was a "test" and the picture is terrible so it looks much better than it appears here. The second to show the lighting. It too is better in person.