IP54 or
IP55?

The IP rating in 30 seconds

The IP rating (International Protection) according to EN 60529 consists of two digits. The first stands for protection against foreign bodies and dust, the second for protection against water.

With IP54 and IP55 the first digit is the same (both dust-protected). The only difference is the second digit — the protection against water.

IP54 vs. IP55 compared directly

Important: neither IP54 nor IP55 is completely dust-tight (that would be digit 6, e.g. IP65), and neither protects against immersion. You will find the full table of all IP levels in the guide to IP ratings.

Which degree of protection do you need?

• IP54 is sufficient if the enclosure is protected from direct water jets: industrial hall, covered or weather-protected outdoor installation, machinery and automation technology.
• Choose IP55 if targeted water jets, heavy driving rain or cleaning with a hose are to be expected — e.g. wash bays, exposed outdoor sites, food and beverage environments.
• Higher (IP65)? If complete dust-tightness is required, or for cleanrooms/food: then go for the SWN series (IP65).

For outdoor cabinets, the design counts for more than the IP digit

A common misconception: the higher the IP number, the more “outdoor-ready” the enclosure. In reality, the IP test describes a laboratory test with defined splashing water or water jets — not real weather. Outdoors it is about rain from above, driving rain, snow, UV and above all condensation. Over the years, what matters is therefore not the second IP digit but how the cabinet is designed — above all, how water is guided and drained away.

What really matters in the design of an outdoor enclosure:

• Raised roof with overhang: directs rain beyond the door gap so that no water runs directly onto the seal and the gap.
• Sloping surfaces & drip edges: the roof and edges are shaped so that water runs off quickly — no standing water, no puddles in beads or on the roof.
• Circumferential door seal & labyrinth: a double-guided sealing edge that keeps driving rain out even in wind.
• Defined water drainage: drainage paths so that any moisture or condensation that gets in drains downwards in a controlled way instead of collecting.
• Ventilation with weather hoods: ventilation openings sit under hoods/labyrinths so that air circulates but no rain gets in.
• Condensation management: heating/ventilation against condensation — because in outdoor operation, moisture from inside is often a bigger problem than the rain from outside.
• Double wall & sun protection: reduce temperature changes and therefore the formation of condensation (→ single-walled or double-walled?).

A well-designed IP54 outdoor cabinet with a raised roof, clean water guidance and condensation management is more robust in real continuous operation than a poorly designed box with a higher IP number. For the vast majority of outdoor applications, IP54 is therefore entirely sufficient — the higher degree of protection only makes sense where targeted water jets (e.g. cleaning with a hose) are actually to be expected. The weatherproof ZPAS SZD outdoor enclosure is designed precisely to these principles.

More on this topic: All IP ratings (IP00–IP68) · Protecting electrical enclosures from dust · Aluminium, steel or stainless steel?