The wrong IP rating on a switchboard is one of the most common, and most expensive, specification mistakes we see in the field. Pick too low and the enclosure fails its environment. Pick too high and you pay for a sealed box that did not need sealing.
Quick answer
IP ratings are a two-digit code defined by IEC 60529. The first digit is solids protection (0-6), the second is liquid protection (0-9). For NZ switchboards, IP41 to IP55 covers most indoor industrial applications, IP66 for food and dairy washdown areas, IP65 for shielded outdoor sites under cover. Match the rating to the actual installation environment, not to a generic specification.
In this article
This guide explains what the IP rating system means, how the digits map to real environments, what the most common NZ applications need, and the specification errors we see most often. Clive Wilson Switchboards, based in Invercargill, has been designing and manufacturing LV switchboards for NZ industrial sites for over 55 years.
IP stands for Ingress Protection. The IP rating is defined by IEC 60529 (also referenced in AS/NZS 60529) and uses a two-digit code:
A higher number in either position means a higher level of protection. IP00 has no protection of either type. IP69K, the highest commonly specified, protects against high-pressure, high-temperature water jets used in food-grade washdown.
For switchboards, the IP rating is type-tested as part of the AS/NZS 61439 assembly verification, declared on the rating plate, and tied to the specific enclosure design.
Typical NZ specifications match the installation environment to a rating band:
Protection against small solid objects (1mm+) and splashing water from any direction. Suits standard indoor switchrooms with clean atmospheres. Default for commercial MSBs and most office sites.
Limited dust ingress prevented; protection against water jets. Suits indoor industrial installations with dust exposure (sawmills, processing plants) or environments where occasional wet-cleaning happens.
Fully dust-tight and protected against powerful water jets. The standard for dairy and food production where high-pressure washdown is part of the cleaning cycle. IP66 (100 L/min at 100 kPa) sits at the top of the practical industrial range without moving into IP67-IP69K specialist territory.
Temporary immersion (IP67) and continuous submersion (IP68). Rare for industrial switchboards. Specialist sub-equipment (sensors, junction boxes) inside an industrial MSB may carry IP67 individually, but the MSB enclosure itself is not usually specified above IP66.
IP rating is a verification item under AS/NZS 61439, type-tested with the specific enclosure construction, gland plate cut-outs and door seals declared in the type-test pack. Substituting an enclosure with different cut-outs or seals breaks the verified IP rating.
AS/NZS 3000 (the NZ Wiring Rules) requires switchboards to be installed in a location and at a rating consistent with the environmental exposure. The IP rating declared on the rating plate must match what is required for the install location.
Over-specifying IP rating adds cost with no safety gain. Under-specifying creates a compliance problem and a safety risk. Match the rating to the actual installation environment.
The second digit (0-9) is liquid protection: 0 no protection, 4 splashing water, 5 water jets, 6 powerful water jets, 7 temporary immersion, 8 continuous submersion, 9 high-pressure/high-temperature jets. For NZ industrial switchboards, the second digit is usually 4 to 6.
IP66 is the common NZ specification for switchboards installed in dairy and food production washdown areas. It is fully dust-tight and protected against powerful water jets used in cleaning cycles.
In practice, no. IP rating is type-tested with a specific enclosure construction. Retrofit seals and gaskets cannot change the verified IP rating of the board. If the application changes, the board needs replacement at the new rating.
Yes. Gland plate cut-outs and cable entries are part of the type-tested IP rating. Field-drilled entries without IP-rated glands break the rating. Use the gland plates and glands specified in the type-test pack, or have the entries factory-cut before delivery.
On the rating plate, alongside rated current, Icw, Ipk, rated insulation voltage and form of internal separation. The IP rating declared on the plate is the rating it was type-tested at.
Reviewed by Chris Wilson, Co-Director, Clive Wilson Switchboards. Registered electrician, 15+ years in LV switchboards. Updated May 2026.
