Types of light bulbs or lamps (C) Daniel Friedman Definitions of Common Lamp (Light Bulb) Abbreviations & Types
Color Temperature & CRI Scale for light bulbs

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Light bulb type codes, abbreviations, features:

Here we define the different types of lamps or bulbs used in lighting fixtures.

We provide a table of Definitions of Common Lamp (Light Bulb) Abbreviations & bulb Types and we explain the CRI scale for lighting and we discuss the color temperature of different types of light bulbs or lamps. We define light bulb (lamp) brightness, define lumens, & discuss light bulb light output in lumens.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Definitions of Common Lamp (Light Bulb) Abbreviations & Types

Halogen interior flood lamps (C) Daniel FriedmanThis article series details guidelines for selecting and installing interior lighting to meet the requirements for different building areas. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

[Click to enlarge any image]

Also see LIGHTING, INTERIOR GUIDE our home page for information about all lighting topics relating to building interior

At left are two indoor halogen flood bulbs, from left a GU/10 and at right an MR-16. These abbreviations and their meanings are explained below.

There are literally thousands of lamps to choose from, but the most common in residential lighting are standard incandescent A lamps, 120-volt BR and PAR directional lamps, and low-voltage PAR and MR lamps, along with a variety of tubular and compact fluorescent's.

Article Contents

How to Read Bulb & Lamp Abbreviations and Codes

While different lamp manufacturers use different codes and abbreviations to label their lamps, most list the wattage first, followed by the bulb shape, width of the bulb (in eighths of an inch), and additional information about the shape and beam angle.

For example, a 50PAR36/H/NSP8° is a 50-watt PAR lamp, 36/8 (4-1/2 ) inches across, halogen with an 8-degree narrow spot beam.

Common abbreviations for types of lamps (light bulbs)

3 Bulb Types © D Friedman at Candle, Globe & General Usage Bulbs

The three lamp or light bulb shapes shown at left are referred to (left to right) as candle light (lampe flamme), globe light (lampe globe), and general purpose light (lampe d'usage general).

All three of these lamps operate at 120V.

The center globe is actually an LED adapted to globe format and with a removable base to permit its use in the same sized smaller base as the candle lamp at left.

Light Bulb Abbreviations

In a next level fo detail in lamp specification the codes below are defined as shown.

Fluorescent lamp (C) Daniel Friedman Fluorescent lamp (C) Daniel Friedman Fluorescent lamp (C) Daniel Friedman Fluorescent lamp (C) Daniel Friedman

Explanation of Color Temperature and CRI for Indoor Lights & Bulbs

Globe bulbs illustrate temperature differences © D Friedman at Color temperature and color rendering index (CRI) are two different ways to characterize how colors appear under a light source.

Our photo illustrates that once a lamp is turned on you may observe significant color temperature differences even among bulbs that look physically the same when "off". The two bulbs at right are giving off a warmer, more yellow-orange spectrum light than the two at left.

Color Temperature is expressed in degrees Kelvin, and for incandescent lights equals the temperature of the metal filament. For fluorescent's and other bulbs without filaments, it is the theoretical equivalent temperature.

Lower color temperatures indicate “warmer” light with more yellow and red tones, which complement skin and natural wood finishes.

Higher color temperatures indicate “cooler” light with more blue and green tones, which renders faces harshly and tends to make skin look pale (Table 5-23).

Skin tones look best under lamps rated from 2700K (standard A-bulb) to 3500K and with a CRI over 80. Residential lamps range as high as 7500K for continuous spectrum fluorescents, such as GE’s Chroma 50 or 75. These simulate daylight and are good for detailed work where color accuracy is critical, but they give skin an unflattering greenish tone.

Table Comparing Color Temperatures of Different Bulb Types

Table 5-23: Color Temperatures of common lamps (bulbs) (C) J Wiley, S Bliss

Also see our separate article Color Temperature Bulb Comparisons in which we give photographs and illustrations comparing color temperature differences among light bulb types and in comparison with natural daylight. There we include a more lengthy table of color temperatures and light sources.

Definition of CRI (Color Rendering Index) Scale Rates Accuracy of Lighting from Various Bulb Types

Halogen work light (C) Daniel FriedmanCRI is a rating on a scale of 1 to 100 of how accurately a lamp shows colored objects. The higher the CRI, the closer the colors look to a standard reference.

For incandescent lamps and all others with a color temperature of 5000K or less, the reference is an incandescent or halogen bulb, which are both assigned CRIs of 100.

For lamps with a color temperature of over 5000K, the reference is natural daylight, which also has a CRI of 100.

CRI numbers are best used to compare lamps with color temperatures within about 300K of each other.

Colors will look very different under a 3000K lamp and a 6000K lamp with the same CRI.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Define Lumens: a Measures Bulb or Lamp or Light-source Brightness

Light comparison in lumens (C) Daniel Friedman

Lumens is a measure of the amount of light contained within an area or within a defined beam or angle emitted from the light source. Lumens is further defined as the total amount of visible light emitted by a source.

Visible here refers to the light spectrum visible to humans. Some other animals are sensitive to light at ends of the spectrum that humans are not.

... emitted by a source seems funny.

If light is not emitted from some source we're not going to see it, right? Well not exactly. There may be ambient light or indirect lighting to complicate matters. So we do talk about light emitted from a particular source so that we can evaluate its output in lumens.

Quantitatively lumens are often defined in luminous flux, at angles in steriradians and measured in candela - terms so unfamiliar to non-engineers that a more familiar practice is to translate lumens roughly into watts.

With an assumption that the light being radiated is in a color that the human eye can best detect (green region at a wavelength of 555nm), then

More lumens means humans see more light. Many but certainly not all lamp bulb packages indicate the brightness of the bulb (when new, since some bulbs degrade or shift in color temperature with age), in lumens.

Lighting Efficacy (brightness) & Lighting Efficiency

As we explain at LIGHTING, INTERIOR GUIDE, in measuring lighting efficacy, the light output of a lamp per electricity consumed, expressed as lumens per watt.

Fluorescent's are three to five times more efficient than standard “A” lamp incandescent's.

And as we note at LAMP & BULB TYPES, INDOOR, some lamps are more energy-efficient, providing more lumens for the same amount of electricity consumed.

Fluorescent's are the most efficient, using up to 70% less energy than an equivalent incandescent bulb (see Table 5-22 in that article).

Watch out: the wattage of a light bulb does not allow you to directly calculate its output in lumens, and equally, lumens of visible light expressed in watts will not translate directly into the rated wattage of light bulbs.

So if you want to be accurate, you should not simply multiply rated-bulb-watts x 683 to calculate lumens.

That's because bulbs are not 100% efficient.

Not all of the energy used by the bulb (measured in watts) produces visible light. Instead, much of the energy, varying by bulb type, is dissipated as heat. Some examples:

Text above was adapted with permission from Best Practices Guide to Residential Construction.

Question: how can I determine which light bulb (lamp) is more efficient? What does mA stand-for?

SCA said:

When comparing compact fluorescent bulbs, on the base of the 1st bulb it has printed 23W 120VAC 60Hz 380mA; the 2nd bulb has 13W 120VAC 60Hz 200mA 800Lumens. My questions are:

a.) what does the #mA refer to?

b.) I'm guessing that the 2nd bulb is more efficient, but how do I confirm that from this information: simply the lower watts with same Hz & VAC; or am I wrong, what does the mA measure?

c.) can I figure out the lumens of the first bulb from the information it has listed? - 2017/07/23 by SCA



a.) The mA refers to milliamps or thousands of an ampere of current drawn when the bulb is operating

b.) Bulb #2 looks more efficient but beware, we are flying through a veritable storm of assumptions.

Here is how I figured that:

Bulb #1 23W 120VAC 60Hz 380mA - no lumens given

Bulb #2 13W 120VAC 60Hz 200mA 800Lumens = 800/13 = 61.5 lumens per watt, which is a typical number for fluorescent bulbs (45-75 lm/W)

If I assume the bulbs are made by the same manufacturer using the same technology, I would choose 60 lm/W and calculate bulb #1 as 23 x 60 = 1380 lumens.

Really? Those numbers are the light output or lumens for each bulb. We just calculated lumens per watt, before considering the amount of energy used to produce those watts.

Let's assume the same light output and then consider the current draw or mA [ I suspect electrical engineers will have a bone to pick with this approach]

Bulb #1: 1380 lm/W / 380mA = 3.63 lm/W/mA

Bulb #2: 800 lm/W / 200 mA = 4.00 lm/W/mA

Bulb #2 looks more efficient but beware, we are flying through a veritable storm of assumptions.

You can compare bulb type approximate efficiency by looking at the lumens per watt or lm/W for each - I'll give data below but be sure to also review our warnings about direct calculation of lumens based just on watts, given at EFFICIENCY & BRIGHTNESS of BULB TYPES

c.) You can estimate the lumens for the 23W fluorescent bulb by using a minimum of 45 lm/W, a typical 60 lm/W or a maximum 75 lm/W. I'll give an example below.

Calculate Amps, Watts, Volts - the formula

Roughly, the current, measured in

Amps (A) = power (Watts or W) / voltage (V)

(experts complicate the formula for accuracy adding in a power factor). Using simple algebra as necessary we can rearrange this formula so that if we know two of the three numbers we can always calculate the third.

For our example 25W incandescent bulb using 120V, Amps = 25 / 120 = 0.21 Amps of current draw

Comparable Efficiency of Flourescent Bulbs of Different mA & Watts

Your 13W (13 Watts) 120V fluorescent bulb at 200mA puts out 800 lumens - 800/150 or about 5.3 times as much light as the 25W incandescent bulb

Your 23W 120V fluorescent bulb draws 380mA or 0.38 Amps and puts out about 375 lumens [1]

Our example 25W (25 watts) incandescent bulb at 210 mA puts out 150 lumens

[1] About your 23W 080mA 120V bulb, I'm uncertain about the accuracy of figuring its lumens from the wattage as there are other factors: bulb filament and coating design, other stuff I don't know.

Comparable Efficiency of Incandescent vs. fluorescent vs LED Bulbs (Lamps)

To compare apples to apples, sort-of,

According to my source

Table of Lumens per Watt by Bulb Type

Tungsten wire incandescent bulbs produce 12.5 to 17.5 lm/W

Halogen lamps - 16-24 lm/W

Fluorescent lamps - 45-75 lm/W

LED lamps 30-90 lm/W

Metal halide lamps 75-100 lm/W

Low pressure sodium vapor lamps 100-200 lm/W

Mercury vapor lamps 36-65 lm/W

Source of lamb & bub abbreviations& codes include


Continue reading at BULB COLOR TEMPERATURE COMPRARISONS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.



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Light Bulb & LampTypes Articles

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