IP68 vs IP51
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP68 and IP51 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 6 vs 5) and liquid protection (level 8 vs 1). IP68 is rated for dust-tight and continuous immersion (manufacturer-specified), while IP51 provides dust-protected and vertically dripping water.
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.
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)
IP68
6 — Dust-Tight
IP51
5 — Dust-Protected
Liquid protection (second digit)
IP68
8 — Continuous Immersion (manufacturer-specified)
IP51
1 — Vertically Dripping Water
Dust-tight
IP68
Yes
IP51
Limited
Water-jet resistant
IP68
Yes
IP51
No
Submersible
IP68
Yes
IP51
No
Outdoor suitable
IP68
Yes
IP51
No
The exact difference (IP68 vs IP51)
Solid protection
IP68
Level 6 — Dust-Tight
IP51
Level 5 — Dust-Protected
IP68 provides "Dust-Tight" (level 6), while IP51 provides "Dust-Protected" (level 5). IP68 is 1 level higher.
Liquid protection
IP68
Level 8 — Continuous Immersion (manufacturer-specified)
IP51
Level 1 — Vertically Dripping Water
IP68 handles Specified by manufacturer (Continuous Immersion (manufacturer-specified)), while IP51 handles 0.1 mm/min drip rate (Vertically Dripping Water). 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.