IP55 vs IP66
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP55 and IP66 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 5 vs 6) and liquid protection (level 5 vs 6). IP55 is rated for dust-protected and water jets (6.3 mm nozzle), while IP66 provides dust-tight and powerful water jets (12.5 mm nozzle).
IP55 is dust-protected and resists low-pressure water jets (6.3 mm nozzle, 30 kPa). A popular industrial rating for equipment exposed to dust and directed water spray but not immersion.
IP66 is dust-tight and resists powerful water jets (12.5 mm nozzle, 100 kPa). A robust outdoor rating for equipment exposed to heavy rain, storms, or directed high-pressure hosing (but not high-pressure washdown).
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP55
5 — Dust-Protected
IP66
6 — Dust-Tight
Liquid protection (second digit)
IP55
5 — Water Jets (6.3 mm nozzle)
IP66
6 — Powerful Water Jets (12.5 mm nozzle)
Dust-tight
IP55
Limited
IP66
Yes
Water-jet resistant
IP55
Yes
IP66
Yes
Submersible
IP55
No
IP66
No
Outdoor suitable
IP55
Yes
IP66
Yes
The exact difference (IP55 vs IP66)
Solid protection
IP55
Level 5 — Dust-Protected
IP66
Level 6 — Dust-Tight
IP55 provides "Dust-Protected" (level 5), while IP66 provides "Dust-Tight" (level 6). IP66 is 1 level higher.
Liquid protection
IP55
Level 5 — Water Jets (6.3 mm nozzle)
IP66
Level 6 — Powerful Water Jets (12.5 mm nozzle)
IP55 handles 30 kPa (Water Jets (6.3 mm nozzle)), while IP66 handles 100 kPa (Powerful Water Jets (12.5 mm nozzle)). IP66 provides 1 level more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
Recommendation
IP66 offers higher overall protection than IP55. Choose IP66 for harsher environments; IP55 may suffice for milder conditions and can be more cost-effective.