When you're working at the house's main electrical panel, protect yourself from receiving a shock:
Stand on a dry surface.
Wear rubber-soled shoes.
Don't touch anything metal, including plumbing pipes or appliances, while touching the electrical panel.
Use one hand to operate the panel; keep the other hand by your side.
Use wooden or plastic ladders, not metal ones.
Extension cords can be handy, but handle them with care. They carry a maximum capacity in watts that's printed on the cable. Electrical appliances such as lawnmowers are also marked with the wattage that they need to draw. If the wattage exceeds the cord's capacity, buy a heavier-duty cord. Do not use extension cords as a substitute for permanent wiring, don't run them under rugs (they could overheat), and don't secure them with metal staples or nails. Replace them if they're frayed or cracked.
Electrical outlets are designed to fit specific plugs: two-prong polarized (with one blade larger than the other); or three-prong, for example. Never alter a plug to fit an outlet that it's not designed for.
Lamps should have maximum wattages clearly marked on them; never use a bulb that exceeds the maximum. Since halogen lamps in particular can become very hot, keep them three feet away from soft furnishings such as curtains or beds.
When buying electrical components — from extension cords to appliances — ensure that they carry the UL sign, showing that they've met safety standards.