AFCI and UL Standards

Mike, I am enjoying the lively discussion on AFCI protection. I would like to add my observations:

1. I find nothing wrong with someone trying to test these devices on their own, however, throwing up one's arms and stating these devices have no merit based on the limited "garage" testing is a little extreme. Perhaps a more reasonable approach is to find out how UL tested the devices. I can think of a number of reasons why Mr. Huddleston's tests may appear to give less than reasonable results. A major one is the use of carbon arc rods to simulate an arcing fault. Keeping in mind that carbon arc rods are designed to maintain a consistent arc, the current wave form may have looked too consistent to fall in the envelope of an arcing fault. Remember, these devices have to be "smart" enough to prevent nuisance trips.

2. UL standards.....I don't think that UL alone dictates equipment standards. Remember, they are a listing agency that establishes testing standards for devices to insure safety from risk of fire, electric shock, or injury. As such, UL standards apply to safety performance issues; noise levels generated, failure modes, risk of shock or fire. UL rarely if ever gets involved with performance issues of efficiency. UL listing is by no means an indicator of quality.

3. Mr. Huddleston’s findings would suggest more scrutiny into the UL listed AFCI's. A number of years ago, a similar issue were raised over "flammability tests" for infant clothing and bedding. After inquiry by consumers (some of who had lost infants) and in particular, "Consumer Magazine", it was determined that testing programs conducted by UL were done to exacting standards. However, the standards employed did not adequately reward those manufacturers making truly fire proof goods. As a result, "fire retardant" clothing and material allowed a wide spectrum of material to share the same listing. As a result of the scrutiny, UL changed their standards of material testing.

4. I agree that manufacturers tend to cram a lot of their special interests into standards and codes...look who makes up a large part of the committees! The NEC and UL will listen to input from others, especially if safety is at issue.

Keep up the good work!
Steinman, E. Chuck. - CPDA,

Mike Holt’s Comment: I wonder what CPDA means.

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