Reading an IP Rating: What IP68 Actually Requires

"IP68" gets used as shorthand for "fully waterproof" more often than it should be. In practice, the two digits after "IP" describe two specific, testable conditions — and the second digit in particular hides a detail that catches a surprising number of buyers out: IP68 isn't a fixed standard the way IP67 is.

What the two digits actually mean

IP ratings follow IEC 60529. The first digit covers protection against solid objects and dust; the second covers protection against water. For cable protection and conduit systems, the second digit is usually the one that matters most.

• IP67 — dust-tight, and protected against temporary immersion: 1 metre of water depth for 30 minutes, under a fixed, standardised test.
• IP68 — dust-tight, and protected against continuous submersion — but the exact depth and duration are defined by the manufacturer, not fixed by the standard.

The detail most buyers miss

IP67's test conditions are the same everywhere: 1 metre, 30 minutes, full stop. IP68 is different by design — the standard requires it to exceed IP67, but leaves the manufacturer to specify how far beyond. A product labelled IP68 might be tested at 2 metres for 24 hours, or 10 metres for 1 hour, and those are not equivalent claims. If continuous submersion at a specific depth is a real requirement for the installation, the datasheet detail — not just the "IP68" label — is what needs checking.

IP rating is a system property, not a single-part property

This is where a surprising number of real installations fall short of their intended rating. A conduit rated IP68 doesn't make the whole run IP68 if the end fitting isn't sealed correctly, or if a sealing washer was left out during assembly. The overall protection level is limited by the weakest sealed point in the system — connector, gland, washer, and conduit all have to be correctly matched and installed for the rating to hold in practice.

Practical checklist for a sealed conduit run

1. Confirm the fitting's IP rating explicitly requires the O-ring and sealing washer to be installed — some ratings are only valid "as supplied," others require the full assembly.
2. Match the sealing washer or ring to the exact thread size (PG or metric) — an oversized or undersized seal won't achieve the rated protection even if it fits by force.
3. Check that every entry point along the run — not just the main conduit body — is sealed to the same standard, including locknuts and clamps at mounting points.
4. If continuous submersion is a genuine requirement, ask for the manufacturer's specific IP68 test depth and duration, not just the label.

Don't over-specify by default

IP68 costs more than IP67, and "higher is always better" isn't actually true in practice — an IP68-rated component tested for deep submersion can, in some cases, trap moisture if the application never actually submerges it, where a correctly-vented IP67 assembly performs better in real conditions. The right approach is matching the rating to the actual environment: occasional splashing or brief flooding calls for IP67; genuine continuous submersion calls for IP68 with a verified depth/duration spec.

The bottom line

IP67 is a fixed, verifiable test. IP68 is a floating specification that still needs its exact conditions checked against the datasheet. And either way, the rating only holds for the complete assembly — conduit, fitting, washer and seal — not for any one component alone.