Corrosion protection for
outdoor electrical enclosures
Updated:
Which corrosivity category applies to your site, which material (stainless steel, aluminium, galvanised steel) is right — and which design measures make an enclosure permanently corrosion-resistant. Explained by the manufacturer.
Outdoors, near the coast or in chemically polluted industrial atmospheres, corrosion is the greatest enemy of an electrical enclosure. Rust on the enclosure body, hinges and locks leads to leaks, penetrating moisture and ultimately failure of the electronics. The right corrosion protection does not begin with the paint finish but with the choice of material and the design.
Short answer: The corrosion protection you need depends on the corrosivity category of the site (EN ISO 12944). For normal outdoor air, powder-coated galvanised sheet steel is sufficient. Near the coast, with salt spray or aggressive chemicals, stainless steel (1.4301 / AISI 304) or aluminium is the right choice. Equally decisive is the careful execution of seals, cable entries and condensation management.
Corrosivity categories: how aggressive is your site?
The EN ISO 12944 standard divides environments into corrosivity categories. They determine what protection is needed:
| Category | Environment | Recommended material |
|---|---|---|
| C1–C2 | Indoors, dry rural outdoor air | Galvanised sheet steel, powder-coated |
| C3 | Urban and industrial atmospheres, moderate humidity | Galvanised steel with high-quality powder coating |
| C4 | Industry with chemicals, swimming pools, high exposure | Stainless steel 1.4301 or aluminium |
| C5 | Coastal areas (salt spray), aggressive industry | Stainless steel 1.4301, 1.4404 on request if required |
| CX | Offshore, extreme chemicals | High-alloy stainless steel, special design |
Choice of material: steel, stainless steel or aluminium?
- Galvanised sheet steel, powder-coated: standard and cost-efficient. With a high-quality powder coating to EN ISO 12944, suitable for C3. For covered or moderately exposed outdoor areas.
- Stainless steel 1.4301 (AISI 304): corrosion-resistant, hygienic, for coastal, food and chemical environments. 1.4404 (AISI 316) on request for even higher resistance to chlorides.
- Aluminium: lightweight, naturally corrosion-resistant (oxide layer), good thermal conductivity. The main material of the ZPAS SZD outdoor series — ideal for telecommunications, energy and transport infrastructure in the open air.
Surface protection: what matters in the coating
With coated steel enclosures, the quality of the pretreatment is decisive: degreasing, phosphating or nano-ceramic pretreatment, followed by powder coating. ZPAS paints in any RAL colour at the factory; the coatings meet the corrosion protection requirements of EN ISO 12944. More on colours and paint finishes: → What are RAL colours?
Design measures — often more important than the material
- Continuous seals (silicone, PU foam) for a high IP rating — keep moisture and corrosive media out.
- Roof overhang / sun shield roof drains rain away and reduces heating.
- Condensation management: thermostat-controlled heating and correct ventilation prevent condensation inside — condensation is one of the most common causes of corrosion.
- Sealed cable entries (e.g. membrane or ROXTEC systems) prevent moisture from entering via the cables.
- Corrosion-resistant fittings: hinges, locks and screws made of stainless steel.
Which IP rating you need for which site is explained here: → IP ratings explained.
The right ZPAS products
For unprotected outdoor locations, ZPAS offers the SZD series outdoor enclosures in aluminium (IP 54/55, IK10, −40 to +70 °C). For corrosive indoor and hygiene environments, the stainless steel electrical enclosures (SWN, 1.4301). Both are available on request in special sizes, with a custom coating and complete thermal management.
A corrosion-resistant enclosure for your site
Tell us the installation site and ambient conditions — we will recommend the material, IP rating and coating and send you a quotation within 2 working days at most. Without obligation.
Request a quote View outdoor enclosures