IP18 vs IP66
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP18 and IP66 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 1 vs 6) and liquid protection (level 8 vs 6). IP18 is rated for > 50 mm — back of hand and continuous immersion (manufacturer-specified), while IP66 provides dust-tight and powerful water jets (12.5 mm nozzle).
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.
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)
IP18
1 — > 50 mm — Back of Hand
IP66
6 — Dust-Tight
Liquid protection (second digit)
IP18
8 — Continuous Immersion (manufacturer-specified)
IP66
6 — Powerful Water Jets (12.5 mm nozzle)
Dust-tight
IP18
No
IP66
Yes
Water-jet resistant
IP18
Yes
IP66
Yes
Submersible
IP18
Yes
IP66
No
Outdoor suitable
IP18
Yes
IP66
Yes
The exact difference (IP18 vs IP66)
Solid protection
IP18
Level 1 — > 50 mm — Back of Hand
IP66
Level 6 — Dust-Tight
IP18 provides "> 50 mm — Back of Hand" (level 1), while IP66 provides "Dust-Tight" (level 6). IP66 is 5 levels higher.
Liquid protection
IP18
Level 8 — Continuous Immersion (manufacturer-specified)
IP66
Level 6 — Powerful Water Jets (12.5 mm nozzle)
IP18 handles Specified by manufacturer (Continuous Immersion (manufacturer-specified)), while IP66 handles 100 kPa (Powerful Water Jets (12.5 mm nozzle)). IP18 provides 2 levels more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
Recommendation
IP66 offers higher overall protection than IP18. Choose IP66 for harsher environments; IP18 may suffice for milder conditions and can be more cost-effective.