IP66 vs IP59K
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP66 and IP59K are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 6 vs 5) and liquid protection (level 6 vs 9K). IP66 is rated for dust-tight and powerful water jets (12.5 mm nozzle), while IP59K provides dust-protected and high-pressure, high-temp water jets.
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 IP59K classification guarantees dust-protected (limited ingress, no harmful deposit) and resistance to high-pressure (8–10 MPa), high-temperature (80 °C) water jets. It is an IEC 60529 ingress protection code combining first-digit (solid) level 5 with second-digit (liquid) level 9K.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP66
6 — Dust-Tight
IP59K
5 — Dust-Protected
Liquid protection (second digit)
IP66
6 — Powerful Water Jets (12.5 mm nozzle)
IP59K
9 — High-Pressure, High-Temp Water Jets
Dust-tight
IP66
Yes
IP59K
Limited
Water-jet resistant
IP66
Yes
IP59K
Yes
Submersible
IP66
No
IP59K
Yes
Outdoor suitable
IP66
Yes
IP59K
Yes
The exact difference (IP66 vs IP59K)
Solid protection
IP66
Level 6 — Dust-Tight
IP59K
Level 5 — Dust-Protected
IP66 provides "Dust-Tight" (level 6), while IP59K provides "Dust-Protected" (level 5). IP66 is 1 level higher.
Liquid protection
IP66
Level 6 — Powerful Water Jets (12.5 mm nozzle)
IP59K
Level 9 — High-Pressure, High-Temp Water Jets
IP66 handles 100 kPa (Powerful Water Jets (12.5 mm nozzle)), while IP59K handles 8–10 MPa (High-Pressure, High-Temp Water Jets). IP59K provides 3 levels more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
Recommendation
IP59K offers higher overall protection than IP66. Choose IP59K for harsher environments; IP66 may suffice for milder conditions and can be more cost-effective.