How do you fit recessed spotlights in a plasterboard ceiling?

With a hole saw in exactly the cut-out size of your spot. Check what sits above the ceiling first, mark out the grid, and cut slowly without pressure. Half a millimetre too wide and the spring clips no longer grip, and you only find that out when the spot hangs down.

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First look at what is behind it

A plasterboard ceiling hangs on battens, and cables run there too. Drill blind and sooner or later you cut through an electrical wire or hit a joist your hole happens to fall across.

If you can get at it, look from above. If you cannot, use a cable detector and tap the ceiling: where it sounds dull there is a batten, where it sounds hollow there is space. Mark the battens in pencil before you cut a single hole.

Mind the recess depth as well. If there are only four centimetres between the plasterboard and the structure above, an ordinary spot will not fit. The Lyvo and the Warmo need 27 mm and will fit there.

Marking out the grid

Centre to centre roughly half the ceiling height, so at 2.60 m that works out at about 1.30 m. To the wall, keep 60 to 80 cm, because a spot too close to the wall throws a bright smear on the plaster.

Mark everything out before you cut, and step back to see whether the grid suits the room. A row of spots that does not run parallel to the wall is something you see for the rest of your life. More on that in How far apart should ceiling spotlights be?

Cutting into plasterboard

The cut-out size is on the box and in the product data, and you follow it to the letter. Ours vary: the Ferro fits Ø50 to 70 mm, the Lesto Ø68 to 75 mm. Spots with a range like that are the most forgiving, because a hole a few millimetres out is then still no problem.

Three things that make the difference:

• Never cut by eye. Use a hole saw in the right size, not a jigsaw along a drawn circle.
• Slowly and without pressure. Plasterboard tears at the edge if you push, and a torn edge gives the spring clips nothing to grip.
• Keep the saw square. Cutting at an angle makes the hole larger than the cut-out size on one side.

If the hole has come out too wide after all, a plaster frame or a spot with a wider visible rim is the rescue. Filling it and cutting again is possible too, but then there is plastering to do.

Concrete is a different story

In a concrete ceiling you do not cut, you drill. That calls for a water-cooled diamond core bit and preferably a drill stand anchored into the concrete. Without a stand the bit wanders and you get an oval hole.

There is also no space freed up behind the spot, so the wiring has to go somewhere. In an existing concrete ceiling a surface-mounted spot is therefore often the wiser choice. The difference between the two is in What is the difference between recessed and surface-mounted spotlights?

Wiring up and finishing off

Switch the circuit off at the consumer unit and check with a voltage tester that there is no voltage left. Flicking the switch is not enough.

Leave some air around the spot. If insulation lies against the fixture, the heat cannot escape and it will fail sooner. How much space is needed exactly is in the spot's instructions.

Then squeeze the spring clips together, push the spot into the hole and let them snap open. If it sits loose, the hole is too big. If it sits crooked, one spring has not caught the plasterboard.

The spots are at recessed spotlights, and for a tight ceiling void there is a separate selection with low recess depth.