Extension cords are designed for temporary, short-term use and are not built to handle continuous electrical loads. Using an extension cord to power a shed or garage long term can increase the risk of overheating, electrical damage, or fire, especially when powering tools, lighting, or appliances.
Permanent power for a shed or garage typically involves running a properly sized electrical circuit from the main panel, using approved wiring methods and grounding. This ensures the electrical system can safely support the intended use while complying with local electrical codes.
Installing a dedicated circuit also allows for proper outlets, lighting, and safety protections such as breakers and GFCI protection where required. A licensed electrician can evaluate power needs and ensure the installation is safe and code-compliant.