About 3,300 home fires per year are caused by damaged or improperly used extension cords. As a result of those fires approximately 50 people are killed and an approximately 250 are injured. In order to prevent fires and injuries follow these guidelines:
Carefully inspect cords for damage before use. Check for cracked or frayed covering sockets, loose or bare wires, and loose connections.
Do not plug one extension cord into one another extension cord.
Extension cords should never be used as permanent wiring. If you need to permanently extend service to an area contact a licensed qualified electrical contractor.
Make sure to check that exterior cords are rated for exterior use.
Only use indoor rated cords indoors and outdoor rated cords for the outdoors.
Make sure that the extension cord is rated for the appliance being plugged into it. The cord should have a tag on it. Compare it to the rating on the appliance manufacturer's label.
Keep outdoor extension cords free of contact with snow and standing water.
Do not overload extension cords.
If you are using too many extension cords because you do not have enough receptacles then it is an indication that you should add receptacles.
Do not nail or staple extension cords to anything.
Extension cords should not be routed through walls, doorways, ceilings, or floors. Do not cover them with anything (e.g. rugs). Covered cords can prevent the escape of heat which could cause a fire.
Never try to plug three-prong (grounded) into two prong (ungrounded) receptacles. Do not cut off the ground pin to force a fit. This could damage the appliance plugged into it and cause electrical shock.
Only purchase extension cords that have been approved by an independent testing laboratory (UL (Underwriters Lab) listed).
Extension cords and power strips should not be used with electrical heaters as the current they draw could cause the cord or strip to overheat and catch fire.