Using a 4” hole saw on wood panel walls to install a round electrical box?

Question

I am mounting a 24 inch vanity light into wood panel walls. The light fixture is lightweight and there is no stud available, so I intend to use this 1 gang old work round electrical box.

I need to know if a 4” hole saw and my drill is a good choice for these wood panel walls. How can I minimize damage to the paint and the wood panels? I’m very concerned about splintering since the wood splinters easily.

The bathroom used to have a recessed medicine cabinet with a light on top and the light switch on the side, so I attached a thin piece of wood to cover up the hole. Next, I’m wiring the new fixture to a combo switch with an outlet. The outlet and light are protected by a GFCI outlet upstream.

Answer 1

It's difficult to say how bad the paneling will splinter, but here are a few pointers.

I have done exactly what you propose to do and find that if I tape over the spot I will be drilling with blue painters tape, the splintering is usually minimal.

Also start with a slow speed and light pressure. Once you have the initial groove formed increase the speed a little. The paneling is soft and will cut easily. Just be sure there isn't anything behind it that you don't want damaged.

Answer 2

You might consider a spiral saw instead. They're much less likely to splinter than a large hole saw. Such saws are unwieldy, and if you let the drill tilt at all they tend to grab and sprain your wrist or zing across the surface when used in awkward situations like this. A spiral saw in a rotary tool (or a dedicated panel cutter) should do well.

Answer 3

You need to use a 4 1/8" hole saw. It will fit much better. I'm an electrician, and that's what we use for round electrical boxes.

Answer 4

Start with the hole saw going in reverse (counterclockwise). It scores the surface without damaging it, and then you can switch to forward (clockwise) and drill through the rest of the way.