IP55 vs IP51
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP55 and IP51 are both IEC 60529 ingress protection codes, but they differ in liquid protection (level 5 vs 1). IP55 is rated for dust-protected and water jets (6.3 mm nozzle), while IP51 provides dust-protected and vertically dripping water.
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.
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.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP55
5 — Dust-Protected
IP51
5 — Dust-Protected
Liquid protection (second digit)
IP55
5 — Water Jets (6.3 mm nozzle)
IP51
1 — Vertically Dripping Water
Dust-tight
IP55
Limited
IP51
Limited
Water-jet resistant
IP55
Yes
IP51
No
Submersible
IP55
No
IP51
No
Outdoor suitable
IP55
Yes
IP51
No
The exact difference (IP55 vs IP51)
Solid protection
IP55
Level 5 — Dust-Protected
IP51
Level 5 — Dust-Protected
Both IP55 and IP51 share the same solid protection: Dust-Protected.
Liquid protection
IP55
Level 5 — Water Jets (6.3 mm nozzle)
IP51
Level 1 — Vertically Dripping Water
IP55 handles 30 kPa (Water Jets (6.3 mm nozzle)), while IP51 handles 0.1 mm/min drip rate (Vertically Dripping Water). 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.