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