IP55 vs IP18
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP55 and IP18 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 5 vs 1) and liquid protection (level 5 vs 8). IP55 is rated for dust-protected and water jets (6.3 mm nozzle), while IP18 provides > 50 mm — back of hand and continuous immersion (manufacturer-specified).
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.
The IP18 classification guarantees protection against solid objects larger than 50 mm and protection against the effects of continuous immersion in water under conditions specified by the manufacturer.. It is an IEC 60529 ingress protection code combining first-digit (solid) level 1 with second-digit (liquid) level 8.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP55
5 — Dust-Protected
IP18
1 — > 50 mm — Back of Hand
Liquid protection (second digit)
IP55
5 — Water Jets (6.3 mm nozzle)
IP18
8 — Continuous Immersion (manufacturer-specified)
Dust-tight
IP55
Limited
IP18
No
Water-jet resistant
IP55
Yes
IP18
Yes
Submersible
IP55
No
IP18
Yes
Outdoor suitable
IP55
Yes
IP18
Yes
The exact difference (IP55 vs IP18)
Solid protection
IP55
Level 5 — Dust-Protected
IP18
Level 1 — > 50 mm — Back of Hand
IP55 provides "Dust-Protected" (level 5), while IP18 provides "> 50 mm — Back of Hand" (level 1). IP55 is 4 levels higher.
Liquid protection
IP55
Level 5 — Water Jets (6.3 mm nozzle)
IP18
Level 8 — Continuous Immersion (manufacturer-specified)
IP55 handles 30 kPa (Water Jets (6.3 mm nozzle)), while IP18 handles Specified by manufacturer (Continuous Immersion (manufacturer-specified)). IP18 provides 3 levels more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
No direct NEMA equivalent.
Recommendation
IP55 offers higher overall protection than IP18. Choose IP55 for harsher environments; IP18 may suffice for milder conditions and can be more cost-effective.