Weatherproofing Your Generator: Rain and Snow Protection

Why Rain and Snow Can Affect a Running Generator

Rain and snow can reach the control panel, the outlets, and the air intakes on a portable generator. Moisture on these parts can make controls slippery and cause water to sit in the sockets. Keeping precipitation off the unit is part of running it during a storm.

Generators produce heat and exhaust while they run, so any cover or shelter must allow air to move. The unit also needs to sit outside on a dry, level surface, away from doors, windows, and vents. A cover does not change where the generator can run.

Shelter Options for a Running Generator

Several types of shelter can keep rain and snow off the top of a generator while it runs. The key is that the sides stay open, or the cover has venting, so exhaust and heat do not build up around the engine. A fully enclosed box, shed, or garage is not a place to run a generator. For help choosing a generator that pairs well with a shelter, see this guide to portable generators.

• Generator running cover: shaped to fit the unit, with cutouts for outlets and controls and vented panels to let heat escape.
• Generator tent: a small canopy with open or mesh sides, designed to stand over the unit.
• Pop-up canopy or event tent: a larger temporary roof that can be anchored, with fully open sides.
• Overhead tarp: a simple rain block that must be set up so sides remain open and wind cannot flip it onto the unit.
• Custom enclosure: a builder-built shelter that has open walls on all sides and a roof; it is not a closed building.

Ventilation and Placement

The generator must receive fresh air to cool the engine and to carry away exhaust. Position the unit on a dry, flat area, with at least a few feet of open space around it. The exhaust should point away from your home, windows, doors, and vents. Follow the maker's manual for your model.

A cover or tent does not replace the rule that a generator runs outdoors only. The Consumer Product Safety Commission and the Centers for Disease Control and Prevention publish what you need to know about carbon monoxide. Read their pages, linked at the end of this article, before you set up a generator during a storm.

Running Covers vs Storage Covers

A running cover is designed for a generator that is on. It has openings for the outlets and the control panel, and it includes ventilation panels or an open bottom so heat can escape. A storage cover is made for a generator that is off, and it usually surrounds the unit completely to keep out dust and moisture.

Do not use a storage cover on a running generator. It can trap heat and block airflow, which raises the temperature around the engine and the alternator. Choose a cover that is labeled for running use if you plan to keep the generator out in the weather while it operates.

For more detail on selecting a cover, see this guide to generator weatherproof covers. If you run a generator in cold weather, read about cold weather operation as well.

What to Look For in a Weatherproof Cover

Measure the generator's length, width, and height before buying a cover. A cover that is too small will sit on the control panel and block access. One that is too large can blow around. The listing or maker's page will state the cover's dimensions; compare them with your unit's dimensions.

• Material that is water resistant and UV resistant, such as heavy canvas, polyester, or vinyl-coated fabric.
• Cutouts that line up with your generator's outlets and control panel.
• Ventilation panels or mesh so heat can escape.
• Straps, elastic, or a drawstring to keep the cover in place on windy days.
• A design that leaves the fuel cap accessible if you need to refuel while the unit is off (never refuel a running generator).

A Cover Does Not Change the Carbon Monoxide Rule

No cover, tent, enclosure, or distance from a wall makes it correct to run a generator inside a garage, basement, shed, crawlspace, or any enclosed space. Carbon monoxide from a generator is deadly, and it can build up even if you leave doors or windows open. The CPSC and CDC both say to use generators outside only.

This article focuses on sheltering the generator from rain and snow. For carbon monoxide safety, read the pages linked in the sources below. If you are shopping for a generator and want a built-in CO shutoff, see our guide to generators with CO sensors. Follow the maker's manual and any local rules. If you have questions about where to place a generator, contact the maker or a licensed professional.

What to pick for your situation

Questions

Can I run a generator under a tarp?

You can, if the tarp is above the unit, the sides remain open, and the unit stays outdoors. A running cover is easier to keep in place and is cut to fit.

Does a weatherproof cover allow me to run a generator in the garage?

No. A cover does not change carbon monoxide rules. Generators must run outdoors only, away from windows, doors, and vents.

What is the difference between a running cover and a storage cover?

A running cover has venting and openings for outlets and controls. A storage cover fully encloses a generator that is off. Use the running cover while the generator operates.

Should I cover my generator when it is not in use?

A storage cover can help when the generator is off and kept in a dry place. Follow the maker's manual for storage and always keep the unit off and cooled down before covering it.

How do I keep a generator dry during snow?

Position it under a shelter with open sides, or use a running cover that sheds snow. Keep the exhaust pointed away from your home and clear snow from the control panel and outlets before starting.