Does anyone know how long a T5 has to burn to obtain maximum output after installation. I thought about 24 hours should be enough time. We had a lighting rep spec fixtures and mounting heights for 200 foot candles, and after install we are only actually reading 120-150. The fixtures have been burning for 4 days. Thanks.
T5 fluorescents
- Thread starter DAWGS
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If you have less than the desired output after 4 days something is wrong. I would contact the rep.
electricalperson
Senior Member
- Location
- massachusetts
installing reflectors behind the lamps could help. did he spec those? the T5 fixtures we put up come with them already installed. or maybe the lighting rep calculated the mounting height wrongDAWGS said:
yes, they have the reflectors. I am sure he has specd something wrong, but he is on vacation this week. Another rep from his company is going to run the numbers again and see what they come up with. Problem is now I have to make good with my customer on this somehow.
JacksonburgFarmer
Senior Member
- Location
- Butler County Ohio
Salespitch.....Maybee......
Salespitch.....Maybee......
I have been working w/ salseman and customer latley on a lighting retro fit... Currently have 1000w MH highbays. Salesman says that the T5ho will replace these 1000w MH hb. Salesman says the actual footcandles will be lower....BUT the percieved level of lighting will be higher. My question was how do you measure percieved level of lighting???? Just a thought. Good Luck....:grin: :grin: :grin:
Salespitch.....Maybee......
I have been working w/ salseman and customer latley on a lighting retro fit... Currently have 1000w MH highbays. Salesman says that the T5ho will replace these 1000w MH hb. Salesman says the actual footcandles will be lower....BUT the percieved level of lighting will be higher. My question was how do you measure percieved level of lighting???? Just a thought. Good Luck....:grin: :grin: :grin:
Not sure what is meant by "perceived level of lighting". Footcandles are footcandles ! You will have a different CRI (color rendering index) between MH and fluorescent. Also, MH is more of a point source of light whereas T5 is linear. Ask rep for clarification.
"perceived level of lighting" can mean a few things. Lighting is kinda like sound where we (humans) do not perceive it on a linear scale. Sound measurement has adjusted to this with dB, which is measured on a logrithmic scale. A 3dB increase is double the volume. Lighting is still on a linear scale. If you double the light it doesn't feel like it was doubled. Imagine a room with dual switched, 4-lamp troffers. If you switch the lights to go from 50% on to 100% on it doesn't feel like the room's brightness doubled.
The other way to look at "perceived level of lighting" is in what's getting lit. Our industry is focused on measuring the light at the work surface right now. An office must have 30-50 fc. That's fine for when you're doing something on the work surface. But when you walk into the office or look up from your desk most of what you see is the ceiling and walls. If the ceiling and walls are dark then the space feels dark. Regardless of the amount of light on the work surface. Example, parabolics are very efficient getting light onto the work surface but it does little to brighten the space.
To the original post, I suspect the rep did the calculations with a light loss factor of 1.00 for the light fixtures. It might also depend on the space you're lighting. How dark are the walls, how much stuff is in the middle of the room (equipment, furniture, etc.) that can absord the light.
The other way to look at "perceived level of lighting" is in what's getting lit. Our industry is focused on measuring the light at the work surface right now. An office must have 30-50 fc. That's fine for when you're doing something on the work surface. But when you walk into the office or look up from your desk most of what you see is the ceiling and walls. If the ceiling and walls are dark then the space feels dark. Regardless of the amount of light on the work surface. Example, parabolics are very efficient getting light onto the work surface but it does little to brighten the space.
To the original post, I suspect the rep did the calculations with a light loss factor of 1.00 for the light fixtures. It might also depend on the space you're lighting. How dark are the walls, how much stuff is in the middle of the room (equipment, furniture, etc.) that can absord the light.
weressl
Esteemed Member
Make sure that on the ballast the number, type and wattage of the tubes correspond to what is connected.DAWGS said:
Make sure that it is 40W tubes and not 32W.
Lighting calculations 'supposed' to take into consideration average mean lumens, not initial and not end-of-life either, wall, ceiling and floor reflectivity, dirt factor as the reflective surfaces loose their efficiency and the optic do not transmit light as new, etc. In essence if it was designed for 200FC - which is EXTREMELY high - you should expect as much as 50% higher initial lighting levels. The lighting levels are also designed for the working surface, so in an office it would be about ~3' and not at floor level.
weressl said:
These are the lighting levels specd by the plant. we are supposed to get the 200 fc from 2.5' off floor. The lamps are 54W. I have lighting rep coming back in the morning to see what we can do. They recalculated their fiqueres and say we should be getting the 200 fc. We will see what they say tommaro.
Are the fixtures enclosed or lensed? How many lamps per fixture? I've noticed the 6-lamp T5HO high bay fixtures can get the lamp temperature over 60 degrees Celcius when there's a lens on the fixture. This is well outside of the 35C ideal operating temperature for T5HO lamps and the light output is significantly reduced.
weressl
Esteemed Member
DAWGS said:
So, did you check the ballast? You would need special High Output ballasts such as Sylvania QTP2x54T5HO/UNV or similar.
Ragin Cajun
Senior Member
- Location
- Upstate S.C.
I have specified T5HO's several times and they have performed beautifully.
Are you sure your light meter is accurate?
What is the spacing, height, room dimensions?
Is this an "open" area or narrow aisles with high bay racks?
Etc.
RC
Are you sure your light meter is accurate?
What is the spacing, height, room dimensions?
Is this an "open" area or narrow aisles with high bay racks?
Etc.
RC
broadgage
Senior Member
- Location
- London, England
All fourescent lamps are temperature sensitive, to a degree, and T5 lamps are more sensitive than older types.
As pointed out above, if the lamps are too hot then the output will reduce, also if the lamps are too cold output will reduce.
Might be worth turning them out for an hour or so, and then measuring the light output when turned on again.
If the output starts high and then declines, this suggests that the lamps are overheating.
If the output starts low and then rises, this suggests that the lamps are too cold.
As pointed out above, if the lamps are too hot then the output will reduce, also if the lamps are too cold output will reduce.
Might be worth turning them out for an hour or so, and then measuring the light output when turned on again.
If the output starts high and then declines, this suggests that the lamps are overheating.
If the output starts low and then rises, this suggests that the lamps are too cold.
A different rep came out yesterday and took some measurements. We think the original guy didn't take in consideration the equipment in the area, and he was about 4' off on the ceiling height, and these fixtures were equipped with an uplight feature. They are goining to recalc everything again and see were we will be. Yes the ballasts are correct. I have a feeling we will be scabbing in more fixtures to get the levels needed.
QuestionGuy
Member
Were the calculations done with T5-HO = 54Watts per lamp and Standard T5 = 28Watt per lamp installed? How many T5 lamps per fixture? What is mounting height? Fixture Spacing?
noonan
Member
- Location
- Bucks County, PA
- Occupation
- Project Manager
I'd like to know why such a high ft-c requirement?
Perceived level of light
This is where you change from orange to white light. Less measured white light will give a feeling of more light than orange. On some of the newer lighting technologies, the salespeople will speak of photopic and scotopic light. Apparently our present light meters only capture one of these types of light but give no consideration for the other. Perhaps someone could explain further the scotopic/photopic issue?
This is where you change from orange to white light. Less measured white light will give a feeling of more light than orange. On some of the newer lighting technologies, the salespeople will speak of photopic and scotopic light. Apparently our present light meters only capture one of these types of light but give no consideration for the other. Perhaps someone could explain further the scotopic/photopic issue?
Photopic vision is the vision of the eye under well-lit conditions.
Mesopic vision is the vision of the eye under intermediate conditions, and is effectively a combination of scotopic and photopic vision. This however gives inaccurate visual acuity and colour discrimination. (luminance level 10-2 to 1 cd/m?)
Scotopic vision is the the monochromatic vision of the eye under low-light conditions. (luminance levels of 10-2 to 10-6 cd/m?)
You can see the shift in color sensetivity at this link.
http://en.wikipedia.org/wiki/Candela
Mesopic vision is the vision of the eye under intermediate conditions, and is effectively a combination of scotopic and photopic vision. This however gives inaccurate visual acuity and colour discrimination. (luminance level 10-2 to 1 cd/m?)
Scotopic vision is the the monochromatic vision of the eye under low-light conditions. (luminance levels of 10-2 to 10-6 cd/m?)
You can see the shift in color sensetivity at this link.
http://en.wikipedia.org/wiki/Candela
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