IP65 vs IP66: What Do the Ratings Mean for Electrical Enclosures?

IP65 and IP66 are common ratings on outdoor electrical enclosures, consumer units, sockets and control equipment. Both indicate a dust-tight enclosure, but the water test behind the second digit is different.

What does an IP rating mean?

IP ratings are defined by IEC 60529 and classify the protection an enclosure provides against access to hazardous parts, ingress of solid objects and ingress of water. The letters “IP” are followed by two characteristic digits.

The rating describes performance under standardised test conditions. It should not be translated into a blanket claim that an enclosure is “waterproof” in every environment.

IP65 vs IP66: what is the difference?

The first digit is identical, so IP65 and IP66 offer the same top-level dust-ingress classification. The difference is the intensity of the water-jet test represented by the second digit.

IP66 does not automatically make a product suitable for immersion. IP67 and IP68 use separate immersion classifications with defined conditions. Nor does IP66 say anything by itself about impact resistance, corrosion or UV stability.

Should you choose IP65 or IP66?

Choose the rating from the real exposure, not simply the highest number available. Factors to assess include:

• Location: indoor, sheltered outdoor, fully exposed or industrial washdown area.
• Water source: rain, cleaning jets, hose direction, spray pressure and duration.
• Dust and contaminants: fine dust, swarf, agricultural material or other airborne solids.
• Temperature and condensation: an enclosure can stop external water yet still experience internal condensation.
• Material: metal and plastic can both achieve an IP rating, while corrosion, UV and impact performance remain separate considerations.
• Equipment inside: heat dissipation, device clearances and manufacturer restrictions can influence enclosure choice.

An IP65 enclosure can be entirely appropriate for many outdoor electrical applications. IP66 is relevant where the risk assessment calls for resistance to more powerful water jets. Browse our electrical enclosures, garage consumer units and weatherproof sockets and switches for product-specific ratings.

What can affect the IP rating after installation?

The marked rating applies to the product in the configuration tested or declared by its manufacturer. Work carried out on the enclosure can reduce its ingress protection if the completed assembly is not made correctly.

• Cable entries: glands, seals and conduit fittings need a suitable rating and must match the cable or conduit size.
• Unused openings: blanking plugs must maintain the required protection.
• Lid and door seals: gaskets need to remain clean, correctly seated and undamaged.
• Drilled or cut openings: modifications must follow the manufacturer’s permitted methods and use suitable components.
• Mounting surface: distortion, uneven fixing or debris can prevent the lid or seal from closing correctly.
• Orientation: drains, vents, hinges and cable entries may have a specified mounting direction.
• Maintenance: seals, glands and fasteners can deteriorate or loosen over time and should be included in inspection regimes.

Where an assembly contains switches, sockets or other fitted equipment, the relevant rating is the rating of the complete finished product—not merely the empty box.

What an IP rating does not tell you

IP65 and IP66 FAQs

Is IP66 better than IP65?

IP66 has a higher water-jet classification, but “better” depends on the environment. IP65 may meet the required exposure while being more appropriate in cost, size or product availability.

Is IP65 waterproof outdoors?

IP65 indicates dust-tight construction and protection against water jets under its test conditions. It is better described by that classification than by the unqualified word “waterproof.”

Can IP66 be submerged?

IP66 is a powerful-water-jet rating, not an immersion rating. Products intended for immersion use IP67, IP68 or another specifically declared classification and set of conditions.

Does drilling an enclosure invalidate IP65?

A correctly made entry using suitable glands or fittings may maintain the required rating, but an unsealed or poorly made opening can reduce it. Follow the enclosure manufacturer’s instructions and verify the completed assembly.

This guide is for general product-selection information. Electrical equipment should be selected and installed by a competent person in accordance with the current edition of BS 7671, the applicable product standards and manufacturer instructions.