Mercury Vapor Lamps
Question and Answer

N.J.A.C. 7:28-41, Mercury Vapor Lamps, deals exclusively with the prevention of unnecessary exposure to ultraviolet (UV) radiation from broken mercury vapor and metal halide lamps that are designed, intended or promoted for illumination purposes. Since a letter went out to all schools in June of this year, apprising them of Subchapter 41 and it’s provisions, the following questions have arisen with regard to achieving compliance:

1. Are metal halide lamps included in Subchapter 41?
2. Does this mean that all HID lamps are included under Subchapter 41?
3. Are there any mercury vapor or metal halide lamps that are excluded from this regulation?
4. What about low wattage light bulbs?
5. What type of material can be used as a protective shield over the lighting fixture that would prevent the lamp from damage and absorb shortwave UV radiation?
6. Just what exactly is meant by the term "non-passive failure"?
7. But I have shatter resistant bulbs. Do I still need shielding?
8. Could heat also be a problem with non-coated bulbs?
9. How do I know if my bulb is rated "T" or "R"?
10. Are there any risks associated with "T" bulbs?
11. I still want to use my "R" bulbs. Can you give me some guidance about safety using them outside?
12. How should I dispose of unwanted bulbs?

1. Are metal halide lamps included in Subchapter 41?

Yes. In 7:28-41.2, the definition of mercury vapor lamps includes metal halide lamps. Metal halide lamps are part of the high intensity discharge (HID) family of lamps that includes mercury vapor and high pressure sodium vapor lamps. Low pressure sodium lamps are technically not a high intensity discharge light but they are usually categorized with other HID sources because the applications are similar.

2. Does this mean that all HID lamps are included under Subchapter 41?

No. High and low pressure sodium lamps are not included in the regulation. But please be aware that most high pressure sodium lamps also have inner arc tubes that contain mercury (generally a lesser amount than the mercury or metal halide lamps) and may possibly present an UV radiation hazard if the integrity of the outer bulb is compromised. With so many new and different types of bulbs on the market, it is best to consult the respective MSDS sheet for potential health hazards. Low pressure sodium vapor lamps do not contain mercury and those intended for illumination purposes do not emit ultraviolet light.

3. Are there any mercury vapor or metal halide lamps that are excluded from this regulation?

Yes. The type that are self-ballasted and have a tungsten filament.

4. What about low wattage light bulbs?

There is no exemption for low wattage bulbs. The regulation applies to all mercury vapor and metal halide lamps.

5. What type of material can be used as a protective shield over the lighting fixture that would prevent the lamp from damage and absorb shortwave UV radiation?

Although special UV filters exist on the market, regular glass or plastic will probably absorb the majority of UV radiation, should a "non-passive failure" occur, providing the filter remains intact. The Department is unable to provide specific data on available shielding/filters for each type of lamp or fixture. For further assistance in this matter, we suggest contacting the supplier of the lamp or fixture.

6. Just what exactly is meant by the term "non-passive failure"?

Non-passive failure is a term used to describe an arc tube rupture. Generally, arc tube ruptures happen at the end of the lamp’s life but may also occur due to external factors such as ballast failure or misapplication. It can result in the discharge of extremely hot quartz particles.

7. But I have shatter resistant bulbs. Do I still need shielding?

It depends. The coating on these types of bulbs are designed to contain glass fragments should the bulbs break. However, some UV radiation will still come through the cracks in the glass. When a "T" or "R" bulb is coated, it does not change the rating. If you have a coated "R" bulb and want to install a protective filter over the fixture, check with your lighting supplier first. The heat that may build up inside the fixture may cause the coating to melt.

8. Could heat also be a problem with non-coated bulbs?

Yes. Before making a decision to enclose existing bulbs, check with your lighting supplier. Some bulbs cannot withstand the heat of an enclosed fixture.

9. How do I know if my bulb is rated "T" or "R"?

Usually, the "T" or "R" rating is marked on the protective sleeve or box that the bulb comes in. It may also be printed on the bulb itself.

10. Are there any risks associated with "T" bulbs?

A bulb’s ability to self-extinguish does not protect against the danger of breakage itself. The arc tubes of metal halide lamps are designed to operate under high pressure and temperature. If the arc tube ruptures for any reason, the outer bulb might break and pieces of extremely hot gas might be discharged into the surrounding environment.

In addition, a self-extinguishing lamp may take as long as 15 minutes to turn off after the outer bulb has been broken. Therefore, if a lamp breaks, even if it is self-extinguishing, people should leave the area immediately.

11. I still want to use my "R" bulbs. Can you give me some guidance about safety using them outside?

Based on the limited experience with lamp use, the Food and Drug Administration suggests that as a general rule, only self-extinguishing lamps ("T" types) or shielded non-self-extinguishing lamps ("R" types) be used in areas where people may remain for more than 15 minutes. Such areas include, but are not limited to outdoor lighted areas where people tend to gather or linger such as building entrances, school parking lots, fairgrounds, sports areas, and certain residential streets. Injuries from broken mercury vapor lamps have been known to occur in some of these areas. Areas where unshielded "R" type lamps may be used safely include highways and other nonresidential roadways and indoor areas having controlled, limited access which are occupied for only short periods of time. Caution should be used, however, in applying the preceding guidance and a decision to use an unshielded "R" type lamp should be made only after carefully weighing all of the relevant factors. If there is any doubt about the type of lamp that should be used, then use a "T" type lamp or a shielded "R" type.

12. How should I dispose of unwanted bulbs?

Check with you town before doing so. Mercury vapor and metal halide lamps contain substantial amounts of mercury and should be disposed of safely.

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