Fire behaviour of plastic parts in electrical appliances—standards versus required fire safety objectives

摘要

For most categories of consumer electrical appliances, UL and IEC standards are typically the only widely used safety standards. A number of these standards are examined to determine if they incorporate technical provisions so that complying products would thereby meet expected fire safety objectives. Specifically, the provisions are examined governing plastic parts in electrical appliances. It is found that the standards do not consistently contain provisions that would, by themselves, suffice for a designer to produce a fire-safe design. Instead, major shortcomings exist, and if an appliance were designed solely to meet the standards and without any additional fire safety considerations, it would not have a reasonable degree of safety. A typical outcome could be a product which is readily ignitable by a small external ignition source and which shows fierce burning upon being so ignited. Furthermore, an internal electrical fault in such a product would probably not be contained within the unit and, rather, would spread to its easily combustible exterior surfaces and produce a similar, fierce fire. It is urged that UL and IEC standards be upgraded so that compliance with the standards would carry a reasonable assurance that fire safety objectives have been met. The recommendations made are intended to cover all UL and IEC appliance standards, not limited to the example cases considered.