August/September may feel like the tail end of storm season, but surprise downpours and hurricane remnants still pose major risks to outdoor electrical systems. From panelboard enclosures to junction boxes, one leaky seal or corroded fitting can invite failure (and liability). Here’s what every contractor should double-check before the next storm rolls in.
The August/September Risk Window
While spring and early summer see the bulk of electrical installations, late summer carries its own hazards. With high humidity, heat, and unpredictable storm patterns, outdoor electrical enclosures face a unique trifecta: thermal cycling, moisture exposure, and UV degradation.
These environmental conditions can weaken materials, deform gaskets, and compromise seals — especially when low-grade or improperly rated enclosures are used. This leaves enclosures vulnerable to water intrusion, equipment failure, and inspection delays.
NEC 110.11 requires electrical equipment to be protected from deteriorating agents such as moisture and corrosion. NEC 300.6 emphasizes the need for protection against corrosion, particularly in outdoor and damp locations. Contractors need to stay vigilant of these codes well into the latter half of the year.
Weatherproofing Starts with the Right Enclosure
Start by confirming that the enclosure’s rating matches the environmental conditions:
- NEMA 3R is suitable for outdoor use, protecting against falling rain and sleet.
- NEMA 4X offers a higher level of protection, including resistance to hose-directed water and corrosion.
Fiberglass-reinforced polyester enclosures, like Allied Moulded’s AM Series, are ideal in storm-prone regions. Unlike metallic enclosures, they won’t rust or dent and offer excellent UV and chemical resistance.
Polycarbonate models also shine in applications where clarity and impact resistance are needed. Both options feature tight sealing mechanisms and enhanced gasketing to ensure long-term durability in wet environments.
Gasket Sealing & Fastening Best Practices
A box is only as weatherproof as its seal. Poor torque application and worn gaskets are among the top causes of ingress. Here’s what to look for:
- Torque Matters: Under-tightening can leave gaps; over-tightening may deform the gasket and compromise the seal. Follow the manufacturer’s torque specifications.
- Gasket Integrity: Look for signs of fatigue, cracking, or pinching. Replace any suspect materials before reinstallation.
- Factory-Applied Gaskets: These provide a consistent, controlled seal compared to field-applied alternatives.
Per UL 50E, environmental enclosures must maintain integrity under mechanical and environmental stress. That includes maintaining gasket compression throughout the product’s lifecycle.
Wire Entry = Water Entry Without Proper Planning
Conduit entry points are often the weakest link in enclosure sealing. When knocked out or drilled incorrectly, they invite water ingress and reduce the enclosure’s protection rating.
That’s why factory-customized, clean-cut knockouts make a difference. These precision-cut entries ensure:
- A better fit with conduit and fittings
- Minimized risk of field damage during installation
- Consistent preservation of NEMA and UL ratings
Use watertight strain reliefs and compression fittings whenever possible, and keep conduit entries below the enclosure when feasible to prevent water tracking inward.
Field Checklist: Verify Before the Next Storm
To help reduce callbacks and inspection failures, run through this quick storm-readiness checklist:
- Enclosure has appropriate NEMA rating (3R, 4X, etc.)
- All cover fasteners torqued to manufacturer specs
- Gasket is intact, seated properly, and not degraded
- Factory-customized, clean-cut knockouts are sealed or fitted with rated connectors
- Conduit entries are pitched downward or drip-looped
- All fittings are corrosion-resistant and watertight
Final Thoughts
Late-summer storms don’t need to kill your projects. With the right enclosure design, attention to sealing detail, and the assurance of factory-customized, clean-cut knockouts, your outdoor installs can handle whatever September throws at them.
Explore Allied Moulded’s lineup of weather-resistant, NEMA-rated enclosures or reach out to match a spec before your next project takes on water.
