wireman1964
Member
how can i provide ft candle calculations for the city for emergency lighting in small commercial bld? Im useing 5.4 watt bugeyes and bodines for 32 watt 4 ft lamp? help
footcandles
- Thread starter wireman1964
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JohnJ0906
Senior Member
- Location
- Baltimore, MD
I think legally you have two options; calculations based on a computer model with measurements taken on a 2'x2' grid pattern, or after the building is constructed but before you have occupancy you can walk around the building well after the sun goes down and take measurements with a light meter on a 10'x10' grid pattern measured at the floor.
The computer model has become standard and expected by the inspectors. I have my own complaints about the accuracy of computer models. But that's a different subject. It's easier to give them what they want.
Lithonia has some free software that you can use to model rooms and areas. You can even get the professional version free if you ask your local rep nicely. http://www.lithonia.com/Software/Lightware7/Visual/Default.asp I can do everything except daylighting on this software. I think Cooper and others also have some free versions. You'll need to started downloading ies files to use in this software. Each variation of a light fixture has a different file to represent the light output of the fixture. There's a big learning curve on the software and you need to think in 3D and pay attention constantly to fixture mounting heights and ceiling heights.
You will find that the bug eyes are very difficult to use to get the light level average you need and not to go over the max:min ratio. If you're using battery packs for the fluorescent fixtures you need to change the lamp lumen value of the fixture you selected. The default value for a 4' T8 is around 2900 lumens per lamp. If you have a 1400 lumen battery pack on a 2-lamp fixture then you need to change this value to 700 lumens per lamp for this fixture. A 3-lamp fixture with only one battery would be 467 lumens per lamp.
The computer model has become standard and expected by the inspectors. I have my own complaints about the accuracy of computer models. But that's a different subject. It's easier to give them what they want.
Lithonia has some free software that you can use to model rooms and areas. You can even get the professional version free if you ask your local rep nicely. http://www.lithonia.com/Software/Lightware7/Visual/Default.asp I can do everything except daylighting on this software. I think Cooper and others also have some free versions. You'll need to started downloading ies files to use in this software. Each variation of a light fixture has a different file to represent the light output of the fixture. There's a big learning curve on the software and you need to think in 3D and pay attention constantly to fixture mounting heights and ceiling heights.
You will find that the bug eyes are very difficult to use to get the light level average you need and not to go over the max:min ratio. If you're using battery packs for the fluorescent fixtures you need to change the lamp lumen value of the fixture you selected. The default value for a 4' T8 is around 2900 lumens per lamp. If you have a 1400 lumen battery pack on a 2-lamp fixture then you need to change this value to 700 lumens per lamp for this fixture. A 3-lamp fixture with only one battery would be 467 lumens per lamp.
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