Satco Products A3521, Catalog

Key

Characteristics

Rated Voltage:

The lamp’s filament is designed to 

operate within a specific volt-

age range in order for it to 

deliver its intended light output. 

Lamps that are burned at volt-

ages higher than their rating will 

result in higher wattage, efficacy 

(lumens per watt) and lumens. 

Lamps operated below their 

rated voltage will significantly 

increase their life while reduc-

ing their wattage, efficacy and 

lumen output.

Lumen Maintenance: 

As the filament of an incandes-

cent lamp burns, the tungsten is 

slowly evaporating and deposit-

ing itself on the interior wall of 

the bulb. This creates the black 

coating seen after a bulb has 

been in use for a while. 

Additionally, as the filament 

evaporates, the lumen output 

decreases until it reaches the end 

of its life when the wire breaks. It is 

recommended that a “group 

replacement” or relamping is 

conducted once a number of 

lamps have failed or a notice-

able decrease in light output has 

taken place.

Burning Position:

For the most part, incandescent 

lamps can be burned in any 

position. However, take note and 

observe a lamp manufacturer’s 

recommendations for use.

Light Output 

vs.

 Life

The life of an incandescent lamp 

and its lumen output are both 

determined by the filament design. 

These characteristics represent a 

give-and-take relationship—one must 

be sacrificed to improve the other. 

There are many choices available to 

the consumer, each one marketed 

for a particular application, purpose 

or feature.

It is important to determine your 

customer’s priorities and needs 

when recommending a light source 

purchase. Is the lamp going to be 

placed in a hard-to-reach area, 

making long life more important than 

light output? Or will it be a workhorse, 

illuminating important tasks and 

needing maximum lumens?

The Federal Trade Commission 

instituted new packaging labeling 

requirements in 1992 to explain the 

function of a lamp better to the 

purchaser. So if you know your way 

around this labeling, you can suggest 

optimum choices for your customer, 

or explain the features to customers 

to allow them to make their own 

educated decisions. 

These examples of actual labels illustrate the differences between two stan-

dard household “A” lamps. One is marketed for longer life, while the other is 

marketed for greater lumen output. Note the life/light tradeoffs.

High Lumen Output

Longer Lamp Life