IP Code First Digit: What 0 to 6 Actually Tests

The first digit of an IP code describes protection against solid objects, from 0 (no protection) to 6 (dust tight). Buyers often read it as a dust rating only, but levels 1 to 4 are about fingers, tools and wires, and they are verified by probes rather than by dust chambers.

Level by level

IP1X uses a 50 mm sphere with a test force of 50 N; IP2X a jointed finger of 12 mm diameter and 80 mm length; IP3X a 2.5 mm rod; IP4X a 1.0 mm wire. In each case the requirement is that the probe does not fully enter, or that the distance to hazardous parts is maintained. IP5X and IP6X switch to a talcum powder chamber, with IP5X allowing limited ingress that must not interfere with operation, and IP6X allowing no ingress at all.

Where testers go wrong

The access probes are dimensioned and force-controlled, and the standard specifies the force for each. Pushing a 1 mm wire harder than specified will always find a gap. Equally, the probe must be applied to every opening, including those covered by a flap or gasket, and the enclosure must be tested in the configuration it is installed in, with cable entries fitted.

Reading a claim

IP6X is dust tight, which is not the same as waterproof. A product can be IP6X and IPX0 at the same time, and many are. Check both digits separately rather than assuming that a high first digit implies anything about water.

Related technical notes

• IPX1 and IPX2 Drip Test: Tilt, Flow Rate and Duration
• IPX3 and IPX4 with the Oscillating Tube: Angle, Flow and Hole Count
• IPX5 and IPX6 Jet Tests: Nozzle, Pressure and Distance