Hi Jeff:
> If a component abnormal test generates excessive and sustained smoke
> (several minutes), but does'nt breach reinforced or double insulation, nor
> emit flame from the enclosure, is it considered a failure? Intuitively, it
> seems like it would be, because of toxicity, but I have been unable to find
> anything in the safety standards to support this. I have checked EN 60950,
> EN 50178, UL 1012, and CSA C22.2 No. 107.1.
For the purposes of product safety and compliance with safety
standards, smoke is a "permitted" emission during fault testing.
The safety issue is whether a safeguard is damaged or breached
due to the heat which produced the smoke. If insulation is not
damaged (as per the hi-pot test), and excessive heat or flame
does not breach the enclosure (as per the cheesecloth test),
then the product is considered acceptable for the purposes of
product safety.
Typically, product safety standards do not address the toxicity
of smoke. This is because all smoke contains toxic materials.
The only solution to smoke toxicity is to eliminate smoke, which
means eliminating all overheating situations. Which is nearly
impossible.
However, any smoke from a product is likely create fear and
anxiety in the mind of the user and nearby persons. Any smoke
in a clean room will likely be cause for scrapping all stock in
the clean room.
While smoke always contains toxic materials (e.g., carbon monoxide),
the concentration of the smoke (toxic material) in the volume of
the room together with the room ventilation determines whether or
not inhalation of the smoke is likely to cause an injury. If the
volume of smoke is small compared to the volume of the room, then
it is likely the concentration of toxic material will be below the
TLV (threshold limit value) for that material.
So, it is a good idea (for the satisfaction of your customers) to
eliminate or reduce any significant smoke emissions that might
occur during fault testing.
Best regards,
Rich
-------------------------------------------------------------
Richard Nute Product Safety Engineer
Hewlett-Packard Company Product Regulations Group
AiO Division Tel : +1 619 655 3329
Effective 6/12/99: +1 858 655 3329
16399 West Bernardo Drive FAX : +1 619 655 4979
Effective 6/12/99: +1 858 655 4979
San Diego, California 92127 e-mail: [email protected]
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