IP40 vs IP51
Head-to-head comparison of two IEC 60529 ingress protection ratings.
IP40 and IP51 are both IEC 60529 ingress protection codes, but they differ in solid-object protection (level 4 vs 5) and liquid protection (level 0 vs 1). IP40 is rated for > 1 mm — small wires and no protection, while IP51 provides dust-protected and vertically dripping water.
IP40 protects against small tools and wires (1 mm objects) but offers no water protection. Useful for indoor equipment needing finer ingress protection against small debris and tools.
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)
IP40
4 — > 1 mm — Small Wires
IP51
5 — Dust-Protected
Liquid protection (second digit)
IP40
0 — No Protection
IP51
1 — Vertically Dripping Water
Dust-tight
IP40
No
IP51
Limited
Water-jet resistant
IP40
No
IP51
No
Submersible
IP40
No
IP51
No
Outdoor suitable
IP40
No
IP51
No
The exact difference (IP40 vs IP51)
Solid protection
IP40
Level 4 — > 1 mm — Small Wires
IP51
Level 5 — Dust-Protected
IP40 provides "> 1 mm — Small Wires" (level 4), while IP51 provides "Dust-Protected" (level 5). IP51 is 1 level higher.
Liquid protection
IP40
Level 0 — No Protection
IP51
Level 1 — Vertically Dripping Water
IP40 provides "No Protection" (level 0), while IP51 provides "Vertically Dripping Water" (level 1). IP51 is 1 level higher.
NEMA equivalents
No direct NEMA equivalent.
No direct NEMA equivalent.
Recommendation
IP51 offers higher overall protection than IP40. Choose IP51 for harsher environments; IP40 may suffice for milder conditions and can be more cost-effective.