IP51 vs IP68
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP51 and IP68 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 5 vs 6) and liquid protection (level 1 vs 8). IP51 is rated for dust-protected and vertically dripping water, while IP68 provides dust-tight and continuous immersion (manufacturer-specified).
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.
IP68 is dust-tight and protects against continuous immersion in water under conditions specified by the manufacturer (typically deeper than 1 meter for prolonged periods). The standard for submersible and marine equipment.
Detailed comparison
The stronger rating on each row is highlighted in emerald.
Solid protection (first digit)
IP51
5 — Dust-Protected
IP68
6 — Dust-Tight
Liquid protection (second digit)
IP51
1 — Vertically Dripping Water
IP68
8 — Continuous Immersion (manufacturer-specified)
Dust-tight
IP51
Limited
IP68
Yes
Water-jet resistant
IP51
No
IP68
Yes
Submersible
IP51
No
IP68
Yes
Outdoor suitable
IP51
No
IP68
Yes
The exact difference (IP51 vs IP68)
Solid protection
IP51
Level 5 — Dust-Protected
IP68
Level 6 — Dust-Tight
IP51 provides "Dust-Protected" (level 5), while IP68 provides "Dust-Tight" (level 6). IP68 is 1 level higher.
Liquid protection
IP51
Level 1 — Vertically Dripping Water
IP68
Level 8 — Continuous Immersion (manufacturer-specified)
IP51 handles 0.1 mm/min drip rate (Vertically Dripping Water), while IP68 handles Specified by manufacturer (Continuous Immersion (manufacturer-specified)). IP68 provides 7 levels more liquid protection.
NEMA equivalents
No direct NEMA equivalent.
Recommendation
IP68 offers higher overall protection than IP51. Choose IP68 for harsher environments; IP51 may suffice for milder conditions and can be more cost-effective.