Electrical fires at home: plugs left in, overloaded power strips and lithium-ion batteries (U.S. and Japanese guidance)

Electrical fires start quietly: a plug left in for years, a cord bunched behind furniture, a power strip doing too much. The U.S. Fire Administration (USFA) estimates there were 23,700 residential electrical fires in 2023. Japan's product safety agency, NITE, and Tokyo's fire department track the same kinds of causes. Here's what both sides recommend.

U.S. guidance

• USFA: "Never use an extension cord with a major appliance."
• USFA: "Use power strips that have internal overload protection."
• USFA: "Replace worn, old or damaged extension cords right away."
• NFPA (a nonprofit association): "Only use one heat-producing appliance" plugged into a receptacle at a time, and extension cords are intended for temporary use.

Japan's guidance

• Tracking. NITE explains that dust and moisture around a plug's prongs can let current arc and carbonize a path until it ignites. Among wiring-device accidents over five years (fiscal 2019–2023), dust- and moisture-related tracking was the most common type. NITE advises cleaning plugs and power strips regularly and unplugging devices you won't use for a long time.
• Load limits. Japanese power strips are labeled with a limit such as 1,500 W. NITE gives typical loads: hair dryer 1,200 W, microwave 1,200 W, iron 1,000 W, electric kettle 1,000 W.
• Don't bundle cords. NITE warns that bundled cords trap heat and the insulation can melt and ignite; Tokyo Fire Department says the same.
• Lithium-ion batteries. NITE counted 2,140 accidents involving products with lithium-ion batteries in 2021–2025, with power banks the most common, and advises against using or storing them in hot places.

A ten-minute check (our suggestions)

• Pull out the fridge or washer and wipe dust off the plug.
• Add up the wattage of everything on each power strip.
• Look for cords pinched under furniture or run under rugs.
• Don't leave power banks in a hot car or a sunny window.
• Test your smoke alarms. See "Smoke alarms, fire extinguishers and a home escape plan."

A Japanese version is available: "差しっぱなしのプラグから出火する" (in Japanese).