<b>Q</b> The light that comes from the ceiling installation in my rented flat is very harsh but my lease doesn't allow me to change light fittings and using lower-wattage bulbs makes little improvement. Can I install a dimmer switch easily - and without damaging the walls? <b>A</b> This is a simple job: you will be replacing the existing switch and using the cavity already made for it, so there will be no damage to any surfaces. <b>What you need</b> A dimmer switch (available from any good hardware store) Two screwdrivers: one for fine work; one larger Electrical tape <b>Before you start</b> When working with electricity, safety is very important. Turn on the light using the switch you are going to replace. Find the electrical breaker panel (the main switch panel for your apartment or house, or "fuse box" in old-fashioned speak) and turn off the breaker that is marked for the same room. If none is marked, just turn off each breaker in turn until you find the one that shuts off the light. Keep it turned off throughout the job. <b>Step 1</b> Unscrew the old switch from the wall, allowing the wires to uncoil from inside the cavity area. (In this case it was a double switch and we want only a single dimmer.) <b>Step 2</b> Most double switches have three wires on them and a small wire that connects the two switches. The wire that leads out of the second switch is the return wire. In the photo it is marked with some green tape. Unscrew one of the other wires from the double switch, insert it into the small hole on the dimmer switch, then tighten the screw to lock it into place. Repeat this step with the return wire, putting it into the middle hole of the dimmer (the location of which may vary). <b>Ste 3</b> With electrical tape, cover the end of the wire that is not needed, in order to insulate it. <b>Step 4</b> Screw the dimmer switch onto the wall where the double switch used to be. Now, turn your breaker back on and enjoy using your new light.