Fire resistance

Enclosures are tested against glow wire standards under the IEC 60695-2-11 series, which model what happens when overloaded connections or overheating components cause a fault.

Glow wire testing is an indirect-flame method: a heated wire is applied to a test sample for 30 seconds, with tissue paper positioned underneath to check for dripping. It measures how well a material resists ignition, whether it self-extinguishes, and whether it drips burning material.

To pass, load-bearing parts near live components must not burn or glow when exposed to a wire heated to roughly 960°C (tolerance depends on the material), any residual glow must go out within 30 seconds of the heat source being removed, and no falling debris should ignite the tissue paper below. This testing regime is what underpins confidence in an enclosure’s fire performance during a real fault condition.

Fire-rated enclosures need to do more than resist heat for a set duration (commonly 30–120 minutes into a fire) — installers also need flexibility to fit them into real-world layouts.

A well-designed fire-rated range gives installers an adjustable mounting rail with multiple height positions, so single or double terminals and different fuse types can be positioned without extra parts. A base carrier that repositions in fine angular steps with a single screw makes it easier to angle terminal blocks in tight or awkward spaces, and pre-fitted, rotatable external fixing lugs speed up mounting on imperfect surfaces. Purpose-built knockouts for cable entry avoid cracked or rough edges during installation.

Underlying all of this is the enclosure’s core material — typically a high-performance, non-conductive polycarbonate that avoids short circuits under fire conditions — which is what keeps critical systems like emergency lighting, alarms, or pressure-boosting equipment operating when it matters most.