# BR30 and BR40 light bulbs



## tractng

Hello,


Can I use BR40 in a BR30 fixture as long as the wattage is under the manufacturer recommended?  It just fits nicer .

tony


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## Wuzzat?

tractng said:


> BR40 in a BR30 fixture as long as the wattage is under the manufacturer recommended?  It just fits nicer .



If the glass bulb size is the same so you get the same amount of free air circulation within the fixture, and the lamp base is in the same base-up or base-down configuration, I can't imagine a reason why you can't.
Of course, UL and the manuf. has the final word on this.


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## tractng

Wuzzat? said:


> If the glass bulb size is the same so you get the same amount of free air circulation within the fixture, and the lamp base is in the same base-up or base-down configuration, I can't imagine a reason why you can't.
> Of course, UL and the manuf. has the final word on this.



Thanks.  The guy at home depot says I can but what do those guys know 

tony


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## Wuzzat?

tractng said:


> Thanks.  The guy at home depot says I can but what do those guys know
> 
> tony


And their bias is in the direction of selling you more bulbs. 

The 40 is 30% larger in diameter than the 30; how much room is left in the fixture?


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## olyj52

tractng said:


> Hello,
> 
> 
> Can I use BR40 in a BR30 fixture as long as the wattage is under the manufacturer recommended?  It just fits nicer .
> 
> tony


I have been in the lighting market for 30+ yrs 

a BR40 bulb is 40/8ths of an inch wide 

a BR30 is 30/8ths of an inch wide

so now you know how bulbs are measured

a F40T12 is 40 watts and 12/8ths of an inch wide


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## Wuzzat?

olyj52 said:


> I have been in the lighting market for 30+ yrs



Why don't they publish the lux levels for bulbs?  It's the reason for buying a bulb.
I had to e-mail the manufacturers to get lux levels for a two-tube troffer and a 75w halogen flood [1800 lux at 5'].


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## tractng

Wuzzat? said:


> And their bias is in the direction of selling you more bulbs.
> 
> The 40 is 30% larger in diameter than the 30; how much room is left in the fixture?



Good amount of room.  They even have a display of the br40 on the same fixture 

tony


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## Wuzzat?

tractng said:


> Good amount of room.  They even have a display of the br40 on the same fixture
> 
> tony


I guess it'll work but if the bulb life is significantly shorter than expected you might try the smaller bulb.


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