Should You Cover Outdoor Electrical Boxes Before Winter? Electricians Weigh In

Covering your outdoor electrical box in winter can protect its components from moisture, extreme temperatures, and other weather damage. However, choosing the wrong cover for electrical boxes can cause more harm than good and can even pose fire safety concerns. To help you protect your outdoor electrical box from the elements, we consulted experts who shared the benefits and drawbacks of electrical box covers, along with installation steps. 

Benefits of Covering

Covering an outdoor electrical box can help prevent moisture buildup, which reduces the risk of electrical shorts and corrosion. "A light, weather-resistant cover keeps wind-driven rain and dew off the enclosure, and in freezing weather it reduces condensation on the metal housing—which is what eventually leads to rust on screws and terminals," says Ahmed Harhara, engineer and founder of HoustonHomeTools.com. Covering outdoor electrical boxes also helps extend the life of the equipment due to reduced wear and tear, says Ben Kolo, owner of Mr. Electric.

Drawbacks of Covering

However, there are some dangers in covering electrical boxes, warns Carl Murawski, a licensed electrician and construction coordinator. "The potential downsides range from nuisance to outright hazardous," he cautions.

Fire hazard is the biggest risk, which happens when the wrong material is used. "Electrical boxes require non-conductive, non-flammable materials," says Micah Jackson-Sattler, owner and head electrician of Micah Electric Co., adding that you should always cover junction boxes with a UL-approved cover.

Never use plastic bags, tarps, or anything airtight that traps humidity. "These actually speed up corrosion and can hold water against the box and hide early signs of damage," Harhara warns. "If someone covers their box, it should be with a purpose-made, vented cover that sheds water but still allows air circulation."

What to Consider When Buying a Cover

If you decide to purchase a cover for your electrical box, look for these qualities: 

• Up to code: "Covers should be UL-approved and made of materials that are non-conductive and non-flammable," Jackson-Sattler says.
• Weatherproof: Look for NEMA-rated 3R or better, suggests Mark Halberg, licensed electrician at Prairie Electric.
• Snug: The covers should fit securely around the electrical box, says Jackson-Sattler.
• Ventilated: "Outdoor covers should have ventilation to avoid condensation," Kolo says. 
• Accessible: "You should still be able to access the box easily without removing the whole thing," Halberg says.
• UV-resistant: "UV-resistant is a plus, since the rays from the sun still do damage," Halberg says.

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Steps for Installation

Follow these steps to install the cover around your electrical box:

1. Cut power to your electrical box from the breaker panel.
2. Remove the old cover and clean out any debris that is trapped inside.
3. Clean the surface around the box, removing any dirt or grime to ensure a tight seal.
4. Install a weather-rated gasket if one isn’t already built into the cover you’ve chosen.
5. Place a new cover over the box, ensuring it is flush with the box and the hinged door opens freely.
6. Line up the screw holes on the cover with the threaded holes in the electrical box, and secure the cover in place using approved screws. Avoid over-tightening.
7. Return to the breaker panel and turn power back on to your electrical box.

When to Call a Professional

If you hear buzzing, see sparks, or smell or feel heat coming from the box, it's time to call a professional, says Murawski. "If you’re unsure about proper code or clearances, or if you need to do any work in the main panel, meter box, or disconnect, call a certified electrician," he says.

If homeowners notice the box has corrosion, it may indicate an issue with the outlet—which should be changed by a professional electrician, says Kolo. "If the GFCIs are tripping after storms or during freezing temperatures, an electrical service professional should be contacted," he adds. "All outlets used outside are required to be rated for exterior use. This is indicated by a WR-rating molded into the outlet. If the outlet doesn't have that rating, it needs to be replaced."

Finally, if you aren't comfortable with any DIY project with proximity to power, Halberg recommends calling an electrician. "If the box is tied to something more complex, like a generator hookup or outdoor panel, don’t even bother trying to DIY that," he warns.