Extension cords and power strips are treated as furniture rather than as electrical equipment, which is how most of the problems with them start.
The first limit is that they are intended for temporary use. Permanent use is not a legal distinction so much as a practical one. Cords run under rugs, behind furniture and through doorways are subject to compression, flexing and abrasion that fixed wiring never sees. Damage accumulates where it cannot be seen.
The second limit is capacity. Cords are rated, and the rating depends on both the conductor size and the length. Voltage drop increases with length, so a long thin cord supplying a heavy load loses voltage, and the appliance draws more current to compensate, and the cord heats. A cord that is comfortable running a lamp at fifty feet is not comfortable running a heater at the same distance.
Space heaters deserve their own paragraph again here. They draw close to the full capacity of a standard circuit, continuously, for hours. Most manufacturers state plainly that they should be plugged directly into a wall outlet. The combination of a heater and a light duty extension cord is one of the more common origins of household electrical fires.
The third limit concerns power strips. A power strip with a breaker or fuse protects itself, not the circuit. Chaining strips together, or plugging a strip into another strip, defeats whatever protection each provides and produces a single point carrying the load of many devices.
Surge protecting strips have the same finite life as any surge device. The protection components degrade with use, and most strips continue to pass power after the protection is exhausted. An indicator light, where present, is worth checking.
A practical rule that avoids most trouble: if a cord is being used in the same place for more than a few weeks, the correct solution is usually an additional outlet rather than a better cord. Adding a receptacle is not an expensive job in an accessible location, and it removes the problem rather than managing it.
Warmth in a cord or a plug under load is always worth investigating.
More on this topic: more from wiki.linux4space.org
