300W Incandescent

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
Small church needs some work done on a couple fixtures and are complaining the lighting doesn't seem as good as it used to be.

The 300 watt lamps they bought are rated @ 130v. Voltage at panel is 119 with them On vs 120 Off.
Can anyone tell me the lumen difference between the design and applied voltage?
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
No, but you can calculate the wattage difference.

They really should get rid of the incandescents.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
The equations in the wikipedia article are drawn from the Welch Allyn incandescent lamp paper and are a good approximation:

going from 130V to 119V you would expect lumen output to go down to (119/130)^3.5 = 0.73 about 73% of the rated value.

-Jon
 
I've probably got a two or or three cases of 300w 120v lamps, and at least some of them are half-silvered. Let me know if you need any :LOL:. (Prev bldg manager bought them way back when and I can't remember every having to replace one since they burn for maybe 8 hours a week.)
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
Not sure of your fixture style, but my previous church had 300-watt incandescents in some warehouse type lights in a gymnasium.

I first switched to 68-watt cfl back in 2010 or 2011

Then about 2017 I found these 30-watt flood bulbs...


They say 250-watt equivalent, but they seemed to be a decent replacement for the cfl's, which were a decent replacement for the 300w incans
 

Flicker Index

Senior Member
Location
Pac NW
Occupation
Lights
What do you mean not as good as it "used to be"? If these lamps were just bought, then silvered bowl that bounces light up into whatever it is above won't have as much light level in the occupied space below compared to a non-mirrored lamp.
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
Not as good as it "used to be" was an observation of an elderly congregation that is not getting any younger. Entirely subjective.

We replaced the incandescents with LED that have the fold down wings. Not the prettiest things but 40% of the congregation said they would rather see. The other 6 weren't there.
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
Not as good as it "used to be" was an observation of an elderly congregation that is not getting any younger. Entirely subjective.

We replaced the incandescents with LED that have the fold down wings. Not the prettiest things but 40% of the congregation said they would rather see. The other 6 weren't there.
One issue that frequently comes up when comparing old lighting to new lighting is the K values. The old bulbs had limited variations the new ones particularly LED seem to have a large variety that doesn't always accurately relate to the old bulb rating. Same lumen at a higher K value will look brighter. Some bulbs are very bad in their interpretation of the lumen/K values in trying to compare bulbs. Had 2 bulbs that were different mfg's same lumen same K value but customer thought one was brighter than the other. One was just slightly more yellow than the other. I couldn't see it until side by side.
 

Flicker Index

Senior Member
Location
Pac NW
Occupation
Lights
One issue that frequently comes up when comparing old lighting to new lighting is the K values. The old bulbs had limited variations the new ones particularly LED seem to have a large variety that doesn't always accurately relate to the old bulb rating. Same lumen at a higher K value will look brighter. Some bulbs are very bad in their interpretation of the lumen/K values in trying to compare bulbs. Had 2 bulbs that were different mfg's same lumen same K value but customer thought one was brighter than the other. One was just slightly more yellow than the other. I couldn't see it until side by side.
At lower illumination level, this is true. The threshold for relevance of scotopic/mesopic lumens is around 3FC according to Google.
 

garbo

Senior Member
Small church needs some work done on a couple fixtures and are complaining the lighting doesn't seem as good as it used to be.

The 300 watt lamps they bought are rated @ 130v. Voltage at panel is 119 with them On vs 120 Off.
Can anyone tell me the lumen difference between the design and applied voltage?
If my old memory serves me right on incandescent lamps for every 1% decrease in voltage there is a 3% decrease in lumen output. Had a customer that owned 2 old apartment buildings with 36 units each. He used traffic lamps that were rated for think 155 volts. The 60 watt lamps looked more like a 25 watt lamp but he was happy due to they lasted think over a year in all the hallway luminares. Church should convert to LED lamps.Only matter of time that they stop making the 300 watt lamps. I have a 130 volt rough service lamp in my hallway ceiling luminare that is over 25 years old. We use it several times a night. Its the last incadescent lamp in my home. Hope this helps.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
The same would be generally true for 300w (or 130v) incandescent, but that doesn't change the point about color vs lumens.
There are much better color-rendering LEDs available now than in earlier generations. The first white LEDs used several mono-frequency diodes to approximate white, while modern ones often uses far blue emitters in conjunction with phosphor mixes to get a smoother spectrum.
Just as early fluorescents concentrated on using the least expensive and most efficient phosphors while youy can pay a premium price to get a better color spectrum these days.
 
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