IEC 60332-1-2 Cable

The IEC 60332 series is a set of internationally recognised test methods for measuring the flame propagation characteristics of electric cables and optical fibre cables under fire conditions. In practice, when an engineer writes “IEC 60332” into a specification, they are requiring the cable to resist fire spread – it must not become a path that carries flames along a cable run.

The series simulates real-world fire exposure in two distinct installation scenarios:

• Single cable testing (Parts 1 and 2) – evaluates one insulated wire or cable at a time, using controlled flame sources to measure how far a flame travels upward on a single vertical or inclined sample.
• Bunched cable testing (Part 3) – evaluates multiple cables mounted together on a vertical ladder tray, replicating the behaviour of a real cable bundle in a riser or tray.

IEC 60332 does not measure smoke density or gas toxicity. It purely assesses flame spread. This is why many projects combine it with other standards such as IEC 60754 (halogen content) and IEC 61034 (smoke density) when low-smoke zero-halogen performance is also required.

Both parts test a single, isolated cable suspended vertically, but they split based on the physical thickness of the cable’s conductor:

• IEC 60332-1 (specifically 1-2): This is the standard procedure for regular-sized cables with a conductor cross-section of 0.5 mm² or greater. It uses a powerful 1 kW pre-mixed propane burner to simulate a substantial localized heat source.
• IEC 60332-2 (specifically 2-2): This part is dedicated to small or thin conductors with a cross-section less than 0.5 mm² (such as delicate instrument wires or telecom lines). Because thin wires melt quickly and cannot absorb much heat, a 1 kW flame would instantly destroy them without accurately measuring the material’s properties. Therefore, IEC 60332-2 uses a much smaller, lower-intensity diffusion flame.

The critical difference comes down to installation density: Single Cable vs. Bundled Cables. This is the most vital distinction for engineering and procurement.

The key difference is that IEC 60332-1-2 tests a single cable, while IEC 60332-3 assesses cables in a bundle. This distinction is crucial for real-world installations.

• IEC 60332-1-2: Tests the flame resistance of a single, vertically-mounted wire or cable using a 1 kW pre-mixed flame. It confirms the cable will self-extinguish and not propagate fire upward when installed alone.
• IEC 60332-3: Evaluates the vertical flame spread of bunched cables—a group of wires lashed together to simulate a real cable tray or duct. The test is far more demanding because cables packed closely together generate much higher fire loads. A cable passing the single-cable test does not guarantee it will pass the bunched-cable test.

A cable’s “reaction to fire” under IEC 60332-1-2 refers to how the jacket and insulation materials interact with an active flame. It evaluates three specific flammability characteristics:

• Ignition Resistance: The cable’s ability to resist catching fire when exposed to a direct 1 kW heat source for up to 8 minutes.
• Flame Propagation Interruption: The material is formulated with flame retardants (such as PVC additives, XLPE matrices, or LSZH compounds) that actively slow down chemical combustion. The flame is restricted from rapidly traveling up the vertical cable run.
• Self-Extinguishing Behavior: This is the ultimate metric. The moment the external 1 kW burner is removed, the cable materials must starve the flame of energy, causing the fire to die out on its own without leaving an excessive path of charred destruction.