To ascertain that our products can reach acceptable average lifetime, the ambient air concentration of a given corrosive gas must comply with following limits: ---

These are the General environmental conditions as per IEC 60721-3-3 and our products confirms to IEC 60721-3-3 by design.

If the concentration is higher in the environment then the specified limit, use minimum an IP54 enclosure with pressurization system to avoid the sulphur atmosphere to get in the enclosure.

The best solution will be to use IP6* enclosure. Place the contactors/ MPCB (and all electrical parts with contacts) in a control room where the air is cleaned, providing a ventilation free off or within the acceptable limits of H2S gas concentrations.