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I am changing out the vanity light, above a sink and mirror, in a bathroom.

The old light fixture had it's own wall plate screwed to the wall that the wires ran into from a hole in the drywall behind.

The new light fixture (just under 10lb in weight) requires an electrical box (as well as being a code requirement.) This house was built in 1980 and does not have an electrical box in the wall so I need to add one.

There are no studs within a few inches (the light needs to be directly above the sink) so I could use a braced box like this:

braced box

But I'd like to avoid tearing a large hole in the drywall if I can safely avoid it.

So, I'm thinking I could attach strips of plywood behind the hole to spread the weight out over a larger area and add one of these:

old work box with ears

The ears of this would rest on the plywood. This way I don't need to make a hole larger than the box.

Do you think this setup will hold a 10lb fixture (assuming the drywall is OK) or should I just rip the hole and add the braced version?

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The braced versions are designed to be installed through the same 4" hole that you'd use for the blue 'old-work' box. I wouldn't trust a 10lb light fitting to be kept up only by the strength of drywall - especially in a damp environment like a bathroom.

  • I couldn't put the screws into the brace ends without pulling out more of the drywall. I've seen the "twist" braces that expand and will fit through the same hole, but without knowing exactly what's run behind the wall (e.g. a vent pipe, or more electrical wiring) I wouldn't want to use those. – rin-tin-tin Oct 26 '16 at 14:26
  • Octagon Box with Old Work Clips – Mazura Oct 26 '16 at 14:35
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    @rin-tin-tin After you cut the hole for the box, you should be able to probe before you twist it into place. The camera on your cell phone works wonders for seeing into tight spaces. – statueuphemism Oct 26 '16 at 14:35
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    2014 NEC reference: 314.27 Outlet Boxes; (A) Boxes at Luminaire or Lampholder Outlets; (2) Ceiling Outlets. At every outlet used exclusively for lighting, the box shall be designed or installed so that a luminaire or lampholder may be attached. Boxes shall be required to support a luminaire weighing a minimum of 23 kg (50 lb). A luminaire that weighs more than 23 kg (50 lb) shall be supported independently of the outlet box, unless the outlet box is listed and marked on the interior of the box to indicate the maximum weight the box shall be permitted to support. – statueuphemism Oct 26 '16 at 14:46
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    @statueuphemism and Mazura Thanks guys. Yes, it's a wall fixture. I saw some old-work boxes "rated" for 10lb, but because the fixture is almost 10lb I didn't want to trust it by itself. Hence I would support it with plywood to spread the load. But I'll try the brace method first. – rin-tin-tin Oct 26 '16 at 17:00

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