noun
emergency light; emergency lamp
Refers to a light that turns on during power outages or emergencies, commonly found in buildings, stairwells, and public facilities.
停電すると、非常灯が自動で点灯します。
When the power goes out, the emergency light turns on automatically.
非常灯のバッテリーを定期的に点検してください。
Please check the emergency light battery regularly.
誘導灯 is a guide light (often green exit signs), whereas 非常灯 is a broader term for any emergency lighting, including backup illumination.
Compound of 非常 (emergency) and 灯 (light). A straightforward modern term with no obscure historical derivation.