IP66 vs IP39K
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP66 and IP39K are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 6 vs 3) and liquid protection (level 6 vs 9K). IP66 is rated for dust-tight and powerful water jets (12.5 mm nozzle), while IP39K provides > 2.5 mm — tool / wire 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).
IP39K is an ingress protection code that ensures protection against solid objects larger than 2.5 mm 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 3 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
IP39K
3 — > 2.5 mm — Tool / Wire
Liquid protection (second digit)
IP66
6 — Powerful Water Jets (12.5 mm nozzle)
IP39K
9 — High-Pressure, High-Temp Water Jets
Dust-tight
IP66
Yes
IP39K
No
Water-jet resistant
IP66
Yes
IP39K
Yes
Submersible
IP66
No
IP39K
Yes
Outdoor suitable
IP66
Yes
IP39K
Yes
The exact difference (IP66 vs IP39K)
Solid protection
IP66
Level 6 — Dust-Tight
IP39K
Level 3 — > 2.5 mm — Tool / Wire
IP66 provides "Dust-Tight" (level 6), while IP39K provides "> 2.5 mm — Tool / Wire" (level 3). IP66 is 3 levels higher.
Liquid protection
IP66
Level 6 — Powerful Water Jets (12.5 mm nozzle)
IP39K
Level 9 — High-Pressure, High-Temp Water Jets
IP66 handles 100 kPa (Powerful Water Jets (12.5 mm nozzle)), while IP39K handles 8–10 MPa (High-Pressure, High-Temp Water Jets). IP39K provides 3 levels more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
Recommendation
IP66 and IP39K offer comparable overall protection; choose based on the specific protection dimension (dust vs. water) that matters most for your application.