IP66 vs IP37
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP66 and IP37 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 6 vs 3) and liquid protection (level 6 vs 7). IP66 is rated for dust-tight and powerful water jets (12.5 mm nozzle), while IP37 provides > 2.5 mm — tool / wire and temporary immersion (up to 1 m).
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).
Specified under IEC 60529, IP37 denotes protection against solid objects larger than 2.5 mm and protection against the effects of temporary immersion in water. Ingress of water in quantities causing harmful effects shall not be possible.. It is an IEC 60529 ingress protection code combining first-digit (solid) level 3 with second-digit (liquid) level 7.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP66
6 — Dust-Tight
IP37
3 — > 2.5 mm — Tool / Wire
Liquid protection (second digit)
IP66
6 — Powerful Water Jets (12.5 mm nozzle)
IP37
7 — Temporary Immersion (up to 1 m)
Dust-tight
IP66
Yes
IP37
No
Water-jet resistant
IP66
Yes
IP37
Yes
Submersible
IP66
No
IP37
Yes
Outdoor suitable
IP66
Yes
IP37
Yes
The exact difference (IP66 vs IP37)
Solid protection
IP66
Level 6 — Dust-Tight
IP37
Level 3 — > 2.5 mm — Tool / Wire
IP66 provides "Dust-Tight" (level 6), while IP37 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)
IP37
Level 7 — Temporary Immersion (up to 1 m)
IP66 handles 100 kPa (Powerful Water Jets (12.5 mm nozzle)), while IP37 handles Hydrostatic ~10 kPa at 1 m (Temporary Immersion (up to 1 m)). IP37 provides 1 level more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
Recommendation
IP66 offers higher overall protection than IP37. Choose IP66 for harsher environments; IP37 may suffice for milder conditions and can be more cost-effective.