MR16 is a US ANSI designation for a multifaceted reflector lamp that is 16/8 inch wide which is approximately 5 cm.
MR16 lamps were originally used for task or display lighting and were not intended for area lighting or downlights. Their narrow beam and dichroic reflector makes them most unsuitable for these applications. They are a form of Tungsten incandescent lamp that contains a halogen gas such as Iodine or Bromine and Xenon, Krypton or other gasses. According to the wikipedia:
"MR16 lamps were originally designed for use in slide projectors."
Other types of lighting such as fluorescent are much better suited for area lighting, however MR16 lighting is often chosen because the initial cost is low and downlights can hide low standards of ceiling fixing. The operating costs, however are very high as generally you may have as many as 4 of them to only light an area of 16 m² with each downlight resulting in a loss of conditioned air in excess of 11 L/s at 50 Pa.
MR16 lamps were originally operated on extra low voltage with a bi-pin GU5.3 base, but it is now common for these to use a GU10 base for mains operation. Mains operation is desirable for downlights as it avoids having a transformer above the ceiling and it also permits the lamp to be upgraded to compact fluorescent. Extra low voltage lamps, however can still be upgraded to LED if a conventional 50 Hz ferromagnetic transformer has been used. Electronic transformers for AC fed extra low voltage Tungsten lamps operate at a frequency too high for rectifiers so can not be converted to LED and must continue to be used with Tungsten lamps.
| Base | Operating Voltage |
|---|---|
| GU5.3 | AC 12 V |
| GU10 | AC 230 V |
| Reflector | A.K.A. | Description |
|---|---|---|
| Cool Beam (Hot Luminaire) | Dichroic | These were designed for use in projectors where excess heat would burn the film. They usually have alternating layers of Titanium Di-Oxide and Silicon Di-Oxide which reflect blue and green light and allow excess red light back through the reflector. This improves light quality, however it has the serious disadvantage for general lighting of allowing Infra-Red radiation which is most of the lights radiant energy back up in to the luminaire. These should not be confused with Non Cool Beam Infra-red Reflective Coating (IRC) lamps which have a Dichroic coating only on the capsule itself to reflect Infra-Red back in so that they can be operated at lower power. |
| Non Cool Beam | ALU Silverback | These have been specifically designed for use in recessed or enclosed luminaires. They have a thick layer of metal as a reflector and Silicon Di-Oxide or some other high temperature coating for protection. Silver reflects more heat away from the luminaire, but is more expensive and requires a protective coating to prevent it from tarnishing. These may employ IRC technology on the capsule itself for energy saving. |
| ANSI | Description | Suitable for downlights? |
|---|---|---|
| BAB: | 20 Watt, 40° beam | Poor uniformity results in low light levels |
| BSB: | 20 Watt, 60° beam | Savings due to lower wattage of lamp itself |
| FMW: | 35 Watt, 40° beam | Poor uniformity results in low light levels |
| FMF: | 35 Watt, 60° beam | Better light levels with more uniform light |
| EXN: | 50 Watt, 40° beam | Excessive number of penetrations required |
| FNV: | 50 Watt, 60° beam | May be suitable if not dichroic |
| FPB: | 65 Watt, 40° beam | Totally unsuitable |
| EYC: | 75 Watt, 40° beam | Totally unsuitable |
This original ANSI went up to 75 W, now 50 W is considered excessive. Some times lower wattage lamps such as 35 W are called FNV even though that designates a 50 W lamp. To avoid confusion specify the beam width in degrees and absorbed power in Watts. Some times other codes are used to designate beam width.
| Other code | Beam width | Area lighting? |
|---|---|---|
| FL (Flood): | 35...40° | Poor uniformity |
| WFL (Wide flood): | 55...60° | Better |
| VWFL (Very wide flood): | >60° | Best |
IEC 60598 has various safety markings some of which are in a nabla '∇' or gradient '▽' symbol.
| IEC | Alternative/AS | Luminaire Use |
|---|---|---|
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INSULATION COVER |
AS/NZS 60598.2.2:2001 - Insulating ceiling F mark: Luminaire is suitable for use in insulating ceilings. |
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IEC 60598-1:1999 - F mark: Luminaire may be mounted on combustible surfaces, however it is unsuitable for use in insulating ceilings. Some times marked "NO INSULATION" for recessed luminaires that don't meet the requirements for use in insulating ceilings. |
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IEC 60598-1:1999 - No F mark: Luminaire suitable for mounting on non-combustible surfaces only. Luminaires with no F marking may only be suitable for this application. Some times marked "MOUNT ON NON- COMBUSTIBLE SURFACE ONLY". |
| 50 W | 35 W 20 W | Do not exceed the marked Wattage even if a non cool beam lamp is to be used. More is not better. For example a 60° lamp will achieve better uniformity and minimum illumination than a higher Wattage spot. |
| IEC | Alternative/AS | Lamp Use |
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AS/NZS 60598.1:2003 - No cool beam: Luminaires rated for insulating ceilings are usually only rated with non cool beam lamps and should have this marking. Only use lamps with this marking in downlights. | |
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AS/NZS 60598.1:2003 - Self-shielded: Downlights often do not include a shield and should have this marking. Only use lamps with this marking in such downlights. Hot fragments from lamp failure may start a fire if not contained. | |
| IEC | Alternative/AS | Transformer Use |
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AS/NZS 60598.1:2003 - Thermal protectors: Transformers with thermal protector of 130 °C or lower and the "F mark" may be mounted on combustible surfaces. If these can not be incorporated with in a suitable luminaire then these can not be covered with thermal insulation. See "F mark" above. |
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Only class <III> Safety Extra Low Voltage terminals are safe. Note that HID and fluorescent lighting use dangerous voltages and may also use separate control gear. |
Some examples of suitable non cool beam MR16 lamps are: AC 12 V Energy Reduction Superia ER50, Coolfit™ 50 Plus?, Eurostar™ Reflekto™ and AC 230 V Hi-Spot® Superia ES50