The UL Standards and SIMCO Enclosures

When you order enclosures from, you are given a choice of UL or non-UL materials. What does that mean? In fact, all SIMCO enclosures are made of materials that meet flammability standards released by Underwriters Laboratories of the USA, but the ones that are labeled UL and have a prefix of UL before the part number are tested to a stricter standard.

UL 94 is the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances. In the test, a sample is held in either a vertical or horizontal position depending on which specification must be met. A flame is applied for a specific amount of time, and the time that it takes for the flame to extinguish itself is measured.

SIMCO's UL rated materials are tested to the 94V0 specification for flame resistance. This means that after a flame is applied, burning stops within 10 seconds on a vertical specimen. The specification also requires that no flaming drips be produced that ignite a cotton indicator placed below the test sample. In the test, the flame is applied twice.

Standard enclosure materials are tested to 94HB. HB stands for Horizontal Burn. To meet this standard, a sample less than 3mm thick must burn at a rate less than 76 mm per minute.

SIMCO uses POLYLAC® PA-765 Acrylonitrile Butadiene Styrene (ABS plastic) for UL rated boxes. A data sheet can be downloaded at

Using UL94V0 rated material ensures greater resistance to flame when exposed to high temperatures and sparks that can be produced in some electrical and electronics applications.

For more information, contact Mike Early at 1-863-452-9090 or visit the SIMCO website at

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