Article
Electrical contractors have a broad range of material options when it comes to choosing enclosures. In some cases, especially where corrosion and chemical exposure are risks, stainless steel can be the best – or only – choice. Stainless steel enclosures stand up to such harsh elements well over the long haul.

Material Matters with Nonmetallic Enclosures

Chuck Ross
Electrical contractors have a broad range of material options when it comes to choosing enclosures. In some cases, especially where corrosion and chemical exposure are risks, stainless steel can be the best – or only – choice. Stainless steel enclosures stand up to such harsh elements well over the long haul. But they’re also expensive, difficult to work with when punch-outs or drilling is required, and that metal body is also an electrical conductor, which could pose safety risks if wires become loose.

Nonmetallic polycarbonate and fiberglass-reinforced polyester boxes pose no such electrical risks and can be much easier to work with at a significantly lower cost in applications where heavy exposure to chemicals and/or corrosive agents won’t be an issue. But these materials aren’t interchangeable, either – each has a sweet spot, when it comes to appropriate applications.

In exterior uses, for example, fiberglass can suffer more from direct UV exposure. A condition called “fiber bloom” can cause color and gloss to fade over time (though not an enclosure’s structural integrity. Some fiberglass enclosure makers add an exterior gel coat that boosts UV resistance significantly. From a budget standpoint, polycarbonate products are less expensive. However, they’re also generally restricted to smaller enclosure sizes.

Polyester/polycarbonate blends offer a third nonmetallic option with some of the benefits of both polycarbonate and fiberglass. These enclosures are fire- and chemical-resistant and can stand up to a gamut of hazards, including solvents, alkalis and acids. This makes them useful in some of the most demanding applications in oil and gas facilities, food processing plants and wastewater plants. They’re also recyclable once they reach the end of their useful life.
Photo courtesy of Allied Moulded Products
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