An extension cord can solve a reach problem while creating a walking problem. During an outage, a cable across a hall is harder to see, and people may be carrying lights, bags, or children. Treat the route as part of the setup rather than tidying it after everything is connected.
Start with the device's permitted power connection. Some appliances should not use an extension cord at all. If a cord is allowed, choose one with the correct rating and environment suitability, following both sets of instructions. Extra length is not a substitute for the right cable.
Look at the route from both directions
Walk from the intended power source to the device, then walk back as someone leaving the room. Notice door swings, chair legs, pet paths, and places a mobility aid could catch. Moving a small device nearer the source may eliminate the need to cross a route altogether.
Do not hide a cord under a rug or pinch it through a door or window. ESFI warns against those arrangements as well as cords that create trips. A concealed cable can still be damaged or overheat, and a mat is not an electrical safety solution.
Do not improvise fasteners that pierce or crush the insulation. If the only available arrangement obstructs an exit, choose another location or another way to power the task. A rechargeable lamp placed on a table may be easier than a mains lamp reached by a long cord.
Inspect before storing and using
Check the full visible length and both ends for cuts, exposed conductors, loose parts, scorch marks, or damaged plugs. Take a damaged cord out of service rather than repairing it with a casual wrap of tape. Do not remove a grounding pin to make a connection fit.
Read any instructions about fully unwinding a reel under load. Keep connections dry and within the product's intended use. An outdoor-rated cord does not make the attached equipment or socket weatherproof.
Extension cords are temporary tools, not a replacement for suitable permanent wiring. If a room always needs a cable across the same route, have an electrician assess a lasting solution. For an outage setup, pack the approved cord with the equipment it serves and record its route so another person does not have to invent one in darkness.