Halogen lighting: Passing the temperature test
By Christian Bollrath
Editor's Note: Some interesting discussion in the WOODnetWORK forum prompted an investigation by the WOODWEB staff into the standards governing the selection of halogen lighting systems. Because halogen fixtures operate at extremely high temperatures (high enough to char typical cabinet surfaces), it is important that cabinetmakers choose components that have undergone appropriate testing.
Our search led us to Christian Bollrath, President of Hera Lighting, Inc., Norcross, GA, who has graciously agreed to "shed some light" on the issues of heat, testing, and halogen fixtures for the readers of WOODWEB.
Halogen cabinet lights can be tested by national testing laboratories like UL or ETL. They are tested according to UL standard 153. UL standard 153 says that the temperature at every part of the wood has to be below 90 degrees C (194 degrees F). This is an internationally accepted safety temperature.
UL standard 153 provides a number of ways to have a halogen cabinet light listed. In this article, I'll examine two common scenarios:
1. Under-cabinet fixture test
The test will be conducted with a 20 W bulb. If the fixture will not pass the test with this bulb the manufacturer can decide to repeat the test with a 10 W bulb. If the fixture passes using the 10 W bulb, the manufacturer must mark the fixture as suitable for up to a 10 W (or smaller) bulb. The manufacturer can also decide to have a listing only for open top applications if the fixture will not pass the pocket hole test.
The test is passed if the temperatures at every part of the board are below 90 degrees C (194 degrees F).
2. Cabinet fixture test
Again, the manufacturer has the choice between 10W or 20W bulbs and open top or pocket hole installation.
The test is passed if the temperatures at every part inside the box are below 90 degrees C (194 degrees F).
If the temperatures inside the standard box are too high, the manufacturer can still have the fixture listed as a cabinet light by listing the minimum box size that will yield the required temperature. The fixture is marked with the minimum acceptable dimensions of the cabinet fixture (e.g. 24" x 24" x 24").
Many advertisements read "UL listed transformer included" or similar. This means that the halogen fixtures have never been temperature tested. It is very important that all components of the lighting system (spot, transformer and connectors) have been tested together.
Although the 90 degrees C is an internationally accepted safety temperature it does not necessarily mean that furniture manufacturers won't have any temperature problems when they are using a UL or ETL listed halogen spots. In the last couple of years my company has discovered that a lot of veneers, laminates, glues and particle boards have a temperature resistance which is below the 90 degrees C. This does not mean that the furniture will burn, but we have seen a lot of applications where the veneer blistered, cracked, or was discolored.
There are numerous halogen systems on the market that satisfy the safety standards outlined above. When choosing a system for your particular application, keep in mind that all components must pass the tests for your installation to be safe and trouble free.
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