Specifying a high quality paint finish on sheet-steel enclosures for use outdoors or in other demanding environment may not be enough to prevent costly damage from rust and other forms of corrosion.

It's quite usual for users to buy well-finished enclosures and then cut holes in them to mount instruments and switches. What they often forget is that the edges of these holes are no longer protected by the paint finish. It is such exposed edges that give corrosion a toehold. After a surprisingly short time this corrosion can spread, seriously damaging the integrity of the enclosure.

One solution is to prime and paint all exposed metal surfaces after the holes have been cut, but this is costly and time-consuming. A more cost-effective solution is to specify grp enclosures in the first place.

No additional finishing is required for holes in grp enclosures and the material is inherently corrosion-proof. There's also another important benefit – drilling and cutting grp doesn't produce conductive or magnetic swarf. With steel enclosures this swarf can cause endless problems to electrical or electronic equipment.

UK enclosure users often ignore the benefits of grp because they believe that they are not as strong as their steel counterparts. In fact, good quality grp have IK impact protection ratings at least as good as those for steel boxes.

Source

Electrical and Mechanical Contractor

Postscript

Brian O'Donoghue, Sarel Schneider Electric