IP51 vs IP55
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP51 and IP55 are both IEC 60529 ingress protection codes, but they differ in liquid protection (level 1 vs 5). IP51 is rated for dust-protected and vertically dripping water, while IP55 provides dust-protected and water jets (6.3 mm nozzle).
With IP51, an enclosure receives dust-protected (limited ingress, no harmful deposit) and protection against vertically falling drops of water. Dripping water shall have no harmful effects.. It is an IEC 60529 ingress protection code combining first-digit (solid) level 5 with second-digit (liquid) level 1.
IP55 is dust-protected and resists low-pressure water jets (6.3 mm nozzle, 30 kPa). A popular industrial rating for equipment exposed to dust and directed water spray but not immersion.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP51
5 — Dust-Protected
IP55
5 — Dust-Protected
Liquid protection (second digit)
IP51
1 — Vertically Dripping Water
IP55
5 — Water Jets (6.3 mm nozzle)
Dust-tight
IP51
Limited
IP55
Limited
Water-jet resistant
IP51
No
IP55
Yes
Submersible
IP51
No
IP55
No
Outdoor suitable
IP51
No
IP55
Yes
The exact difference (IP51 vs IP55)
Solid protection
IP51
Level 5 — Dust-Protected
IP55
Level 5 — Dust-Protected
Both IP51 and IP55 share the same solid protection: Dust-Protected.
Liquid protection
IP51
Level 1 — Vertically Dripping Water
IP55
Level 5 — Water Jets (6.3 mm nozzle)
IP51 handles 0.1 mm/min drip rate (Vertically Dripping Water), while IP55 handles 30 kPa (Water Jets (6.3 mm nozzle)). IP55 provides 4 levels more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
No direct NEMA equivalent.
Recommendation
IP55 offers higher overall protection than IP51. Choose IP55 for harsher environments; IP51 may suffice for milder conditions and can be more cost-effective.