MR16
Encyclopedia
LED lamp
An LED lamp is a solid-state lamp that uses light-emitting diodes as the source of light. The LEDs involved may be conventional semiconductor light-emitting diodes, organic LEDs , or polymer light-emitting diodes devices, although PLED technologies are not currently commercially available.Since...
s are also available. MR16 lamps are regularly used in place of standard incandescent light bulb
Incandescent light bulb
The incandescent light bulb, incandescent lamp or incandescent light globe makes light by heating a metal filament wire to a high temperature until it glows. The hot filament is protected from air by a glass bulb that is filled with inert gas or evacuated. In a halogen lamp, a chemical process...
s for applications including residential lighting and retail lighting, while MR11 ones are used in specialty applications. MR16 lamps were originally designed for use in slide projector
Slide projector
A slide projector is an opto-mechanical device to view photographic slides. Slide projectors were common in the 1950s to the 1970s as a form of entertainment; family members and friends would gather to view slide shows...
s. They are well suited to a variety of applications that require directional lighting of low to medium intensity, such as track lighting
Track lighting
Track lighting is a method of lighting where light fixtures are attached anywhere on a continuous track device which contains electrical conductors. This is as opposed to the routing of electrical wiring to individual light positions. Tracks can be mounted to ceilings or walls, lengthwise down...
, recessed ceiling lights
Recessed light
A recessed light or downlight is a light fixture that is installed into a hollow opening in a ceiling...
(only if not dichroic
Dichroic filter
A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color of light that they...
), desk lamps, pendant
Pendant light
A pendant light, sometimes called a drop or suspender, is a lone light fixture that hangs from the ceiling usually suspended by a cord, chain, or metal rod. Pendant lights are often used in multiples, hung in a straight line over kitchen countertops and dinette sets or sometimes in bathrooms. ...
fixtures, landscape lighting, retail display lighting and bicycle headlights.
Designation
MR16 is a coded designation in which MR stands for multifaceted reflector, and 16 is the number of eighths of an inch the front is in diameterDiameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
. An MR16 is 2 inches (51 mm), an MR11 is 1.375 inches (35 mm).
Design and construction
Halogen MR16 lamps consist of a halogen capsule (bulb) integrated with a pressed glass reflector. The reflector of an MR16 lamp is 2 inches (51 mm) in diameter. The base conforms to bi-pin GU5.3 standard. The compact size of the MR16 allows for much smaller, more discreet fixtures than the incandescent reflector bulbs that pre-dated MR16s.The reflector controls the direction and spread of light cast from the lamp. MR16 lamps are available with different beam angles from narrow spot lights of as small as 7° to wide flood lamps of 60°.
"MR" refers to multifaceted reflector, indicating that this reflector is usually shaped with multiple small facets. This multifaceted reflector gives a soft edge to the area illuminated by the lamp. MR16 lamps are also available with smooth reflectors, resulting in a sharper fall-off to the illuminated area. "16" refers to the maximum diameter of the lamp in eighths of an inch, 16/8" or 2 inches (51 mm).
Dichroic reflectors
Some lamps use aluminum coating as a reflector while some lamps use selective pass/block dichroicDichroic filter
A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color of light that they...
coating that reflects particular frequencies of the visible spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
in the direction the lamp is facing, while not reflecting infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
light. By not reflecting infrared light (which produces heat), these lamps reduce the amount of heating of the subject upon which they are focused.
Dichroic
Dichroic filter
A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color of light that they...
lamps, however, must never be used in recessed lighting, as they are a common ignition source for building fires. In some countries, e.g., the EU and Australia, lamps unsuitable for use in recessed lighting can be identified by the IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
60598 No Cool Beam symbol.
Operation
The brightness of MR16 lamps can be adjusted when used with appropriate light fixtureLight fixture
A light fixture, light fitting, or luminaire is an electrical device used to create artificial light and/or illumination, by use of an electric lamp...
s and dimmer
Dimmer
Dimmers are devices used to vary the brightness of a light. By decreasing or increasing the RMS voltage and, hence, the mean power to the lamp, it is possible to vary the intensity of the light output...
s. However, the color temperature
Color temperature
Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of...
changes significantly when the lamp is dimmed.
MR16 lamps produce significant heat, and care must be taken to avoid contact with skin or proximity to flammable materials when the lamp is on or has been on recently.
Low voltage halogen lamps, such as MR16 lamps often has a better efficacy than line voltage incandescent lamps but not nearly as efficient as gas discharge lamps or some LED lamps.
With both types of incandescent bulbs, useful life can be considerably shortened if their filaments experience mechanical shock or vibration. Using an electronic transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
with a "soft start" feature can considerably extend life, as it reduces the characteristically high inrush current
Inrush current
Inrush current, input surge current or switch-on surge refers to the maximum, instantaneous input current drawn by an electrical device when first turned on. For example, incandescent light bulbs have high inrush currents until their filaments warm up and their resistance increases...
that occurs initially when the lamp is cold.
MR16 lamps, like all quartz-halogen lamps, produce some ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light. Usually, this must be filtered out. Also, the quartz capsule of the lamp sometimes ruptures ("explodes
Exploding light bulb
An exploding light bulb is a tungsten halogen or high-intensity discharge lamp, which ruptures explosively. Because these lamps operate with high pressure inside a high-temperature envelope, explosion can result in small pieces of hot glass ejected at high speed.- Causes of bulb explosion :If the...
") upon failure of the lamp. For these two reasons, some MR16 lamps include a cover glass that serves as an integrated ultraviolet filter and explosion shield. MR16 lamps lacking this cover require the use of a fixture that incorporates an external piece of glass specifically designed to provide this protection.
MR16 lamps are available in 10–50 W power ratings (150–800 lumens).
Compatible LED replacements
LEd
LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....
lamps are also available. They are similar in shape to halogen MR16 lamps, and can be used in most fixtures designed for MR16 lamps. The same is true of MR11-compatible LED lamps.
Versions of the led lamps have been patented in the UK.{PATENT NO.GB2397943} Due to the low heat and power consumption, they have been produced from plastic, although this does not affect their efficiency. Their non-polarised AC/DC operation, with current limitation over a wide voltage range (11.5 ~ 18 volts as a standard 12 volt version), allows a wide range of usage.
Average rated life, as quoted by manufacturers, is typically 30,000 to 50,000 hours, depending on the product. This amounts to continuous operation for 1250 to 2080 days, or approximately 24 hours per day for three to six years.
Fixtures designed for halogen MR16 or MR11 lamps that use electronic transformers may need to be retrofitted with LED-compatible transformers. This is because the standard electronic transformers have a minimum power-usage requirement in order to function. Some LED-lamps may be below this usage requirement. Fixtures that use magnetic transformers can generally be used with LED-lamps without modification.
LED-lamps from some manufacturers incorporate full wave rectification circuitry into the lamp, so that either AC or DC can be used, while others require a DC supply and correct polarity.
At this time, there are few standards for MR16 and MR11 compatible LED lamps. As such, there is a wide variety of designs, varying significantly with regard to beam width, light colour, efficiency and luminous power.
Unlike halogen MR16s, LED-lamps often do not have the multifaceted reflectors that give MR16s their precise beam width control. Some rely on the optics of the LED(s) to control the beam width. Some designs may have simple cut-off apertures that limit beam width, or even individual reflectors for each LED.
As with other LED lamp
LED lamp
An LED lamp is a solid-state lamp that uses light-emitting diodes as the source of light. The LEDs involved may be conventional semiconductor light-emitting diodes, organic LEDs , or polymer light-emitting diodes devices, although PLED technologies are not currently commercially available.Since...
s available today, the quality and color temperature of the white light produced by such lamps varies. Many tend towards the blue end of the spectrum, being even "cooler"-coloured than fluorescent lighting. Because of this variability, some MR16 and MR11 compatible LED lamps will create significantly more natural looking light than others.
The least efficient of these lamps produce about 26 lumens per watt (lm/W), which is similar to the efficiency of halogen MR16s. The most efficient of these lamps available today produce about 100 lm/W, which exceeds the efficiency of compact fluorescent lamps.
In terms of total luminous power, such lamps range from being significantly less powerful than their halogen counterparts, to being comparable to the lower power halogen MR16s. The brightest available halogen MR16s are still slightly brighter than the brightest available LED versions.
Variations
MR16 lamps most often operate at 12 volts, although they are also available in other voltages. The common 12-volt MR16 lamps, therefore, require a ferromagnetic or electronic transformerTransformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
— sometimes misnamed as a ballast
Electrical ballast
An electrical ballast is a device intended to limit the amount of current in an electric circuit. A familiar and widely used example is the inductive ballast used in fluorescent lamps, to limit the current through the tube, which would otherwise rise to destructive levels due to the tube's...
— to convert the 120 or 230 volt mains voltage
Mains electricity
Mains is the general-purpose alternating current electric power supply. In the US, electric power is referred to by several names including household power, household electricity, powerline, domestic power, wall power, line power, AC power, city power, street power, and grid power...
to the very low operating voltage
Voltage source
In electric circuit theory, an ideal voltage source is a circuit element where the voltage across it is independent of the current through it. A voltage source is the dual of a current source. In analysis, a voltage source supplies a constant DC or AC potential between its terminals for any current...
required by the lamp. MR16 lamps may also be operated from direct current, but will have a shortened life.
Although halogen incandescent MR16 lamps usually operate on AC voltage, LED devices require direct current and require a rectifier
Rectifier
A rectifier is an electrical device that converts alternating current , which periodically reverses direction, to direct current , which flows in only one direction. The process is known as rectification...
and current
Current source
A current source is an electrical or electronic device that delivers or absorbs electric current. A current source is the dual of a voltage source. The term constant-current sink is sometimes used for sources fed from a negative voltage supply...
driver in the unit. The current driver is commonly a buck–boost converter or buck converter
Buck converter
A buck converter is a step-down DC to DC converter. Its design is similar to the step-up boost converter, and like the boost converter it is a switched-mode power supply that uses two switches , an inductor and a capacitor....
. The rectifier must be able to operate efficiently at the high frequencies produced by electronic transformers and should also incorporate safety devices that operate in the event of component failure.
Certain MR16 lamps can operate directly on the mains voltage. These lamps typically use a GU10 turn-and-lock base, so they cannot be accidentally interchanged with low-voltage lamps. They are often referred to as GU10, rather than MR16 lamps. Because their filaments are finer, they are much more fragile than those used in low-voltage lamps.
Low-voltage MR16 lamps almost always have ANSI standard GU5.3 two-pin bases. MR16 lamps with an integrated transformer are also available. These lamps have screw bases to fit standard medium-base Edison sockets
Edison screw
The Edison screw fitting is a system of connectors used for light bulbs, developed by Thomas Edison and licensed starting in 1909 under the Mazda trademark. Most have a right-hand threading, so that it goes in when turned clockwise and comes out when turned counterclockwise, like a hardware screw...
.
Smaller lamps are also manufactured in the less common MR11 and even less common MR8 formats, which have reflectors that are 1⅜ inch (11/8" or 35 mm) and 1 inch (8/8" or 25 mm) in diameter, respectively. These smaller lamps appear very similar to MR16 lamps, also featuring similar multifaceted reflectors that are available in a variety of beam spreads. Their smaller size makes possible even smaller fixtures, but limits them to lower powers. MR11 and MR8 lamps have pins placed closer together, preventing them from accidentally being interchanged with MR16 lamps.
PQL INC. Produces a wide variety of color temps. in 3W LED MR16's 30K,35K,50K and 65k for precise color applications and specialty installations including landscape lighting. These lamps replace a 35W MR16.
Advantages
MR16 lamps offer several advantages over other lamps with equivalent wattage ratings. They are typically smaller (transformers excepted), provide better beam control and offer a whiter light than ordinary incandescent lamps. The small size of the lamp allows designers more flexibility in placing the lamps and with the option of various beam widths, the light beam can be very specifically placed. The light output properties of the LED lamps provides a whiter light (higher color temp and higher Color Rendering Index) that enhances the color of illuminated objects.Disadvantages
MR16 lamps have several disadvantages over other types of lighting, most notably their high operating temperature and pressurized bulb. The halogen bulb can reach temperatures over 200°C, increasing the risk of fire should anything flammable come in contact or even be in close proximity to the bulb or fixture. The quartz capsule containing the filament and halogen gas is pressurized and can explode if improperly handled or damaged, and must be handled carefully prior to installation to prevent contamination with oil and salt from fingerprints, which can dramatically shorten the lamp's life.Mounted clear of roof insulation and with an inbuilt air space around the luminaire fitting, they effectively form small chimneys resulting in heat lost from the room space to the roof space.
In dusty environments, the high temperatures produced contribute to a burnt smell; depending on the type of dust, the smell can be as pleasant as toast or as bad as having a nearby oil refinery.
Compact fluorescent versions that can replace the MR16 exist, run at safe temperatures, and consume only a few watts, but typically scatter the small amount of light produced widely, thus making them suitable only for limited applications.
ANSI designations
American National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
standard codes are used to designate certain power and beam angle combinations for MR16 lamps. Many manufacturers use these standard codes for lamps matching these specifications:
- ESX: 20 watt, 10 degree beam (20MR16/10°)
- BAB: 20 watt, 35 degree beam (20MR16/35°)
- EXT: 50 watt, 15 degree beam (50MR16/15°)
- EXZ: 50 watt, 25 degree beam (50MR16/25°)
- EXN: 50 watt, 40 degree beam (50MR16/40°)
- FNV: 50 watt, 60 degree beam (50MR16/60°)
- FPA: 65 watt, 15 degree beam (65MR16/15°)
- FPC: 65 watt, 25 degree beam (65MR16/25°)
- FPB: 65 watt, 40 degree beam (65MR16/40°)
- EYF: 75 watt, 15 degree beam (75MR16/15°)
- EYJ: 75 watt, 25 degree beam (75MR16/25°)
- EYC: 75 watt, 40 degree beam (75MR16/40°)
Note that MR16 lamps are available in many other power and beam combinations than those available above. For this reason, MR16 lamps are also often labeled according to beam spread abbreviations. Note that these while these abbreviations are commonly used, the angles associated with these abbreviations vary slightly from manufacturer to manufacturer. These are typical beam angles for these beam spread abbreviations
- VNSP (very narrow spot): less than 8 degrees
- NSP (narrow spot): 8-15 degrees
- SP (spot): 8-20 degrees
- NFL (narrow flood): 24-30 degrees
- FL (flood): 35-40 degrees
- WFL (wide flood): 55-60 degrees
- VWFL (very wide flood): 60 degrees or more