IPX3 and IPX4 are the lowest water ratings that use moving water, and they are where a lot of "it passed here, failed there" arguments start. The equipment is simple, the standard is specific, and the gap between the two comes down to how wide the arc is and whether the spray reaches the whole surface. Get the arc, the flow per hole and the timing right and the result is reproducible.
The oscillating tube
Both IPX3 and IPX4 use a pivoting tube with a row of holes above the sample. IPX3 swings through a 60° arc (±60° from vertical, i.e. 120° total on the sides) to simulate rain falling on a tilted enclosure. IPX4 swings through 180° per side, so water reaches the top as well. The tube does the work; the difference between the two ratings is mostly the swing angle, not a different nozzle.
| Parameter | IPX3 | IPX4 |
|---|---|---|
| Arc of swing | ±60° (120° total) | ±180° (360° on two sides) |
| Flow per hole | 0.07 L/min | 0.07 L/min |
| Total flow | Set by number of holes in the arc | Higher, full ring used |
| Duration | About 5 min per position, or 1 min/m² | Same timing basis |
The splash nozzle
IPX4 also has an alternative: a handheld spray nozzle covering a 120° cone, run for about five minutes from every practical direction. Some labs prefer it for awkward shapes the tube cannot cover evenly. If you use the nozzle instead of the tube, say so on the report, because the two are not identical in coverage.
Flow and timing
The flow is defined per hole, and the total is the product of holes-in-arc and that rate. A blocked or scaled hole changes the total flow and the distribution at the same time, so inspect the tube before each series. The timing basis is a minimum of about five minutes per position, or one minute per square metre of exposed area, whichever keeps water on the surface long enough. A stopwatch started late or stopped early quietly weakens the test.
- Verify hole count and flow before the run, not after.
- Keep the sample centred under the arc it is meant to see.
- Rotate or reposition so all faces get their time.
- Record the actual duration and flow, not just the rating.
Sample condition and judging
Test the enclosure as delivered: glands fitted and torqued, covers fastened, drains in service state. After the run, wipe the outside and open the enclosure promptly, photographing the inside before touching anything. A few drops on an internal wall below the entry may be acceptable; water on a terminal block, a live part or insulation that could track is not. If the interior looks misted rather than wetted, let it dry in a warm room and re-inspect, because condensation is not ingress.
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