While cutting the hole for the box to add a switch in a finished house - I note that the mounting tabs and hardware on the outside of a receptacle box would require a large or messy hole to accommodate the box - is there a specific box that works best for this purpose? (the 1110 box comes to mind - it is smooth but also too large) Also - I intend to use a bendable drill extension designed for this purpose to drill a hole through to the bottom of the wall - (I'll have a peek with a mirror before I drill) - I wonder whether there it is necessary to protect the wall somehow from damage where the drillbit inserts through the hole to prevent damage of the drywall. My intention is to use bx for the wiring - thanks
I don't think that a handy box is rated for a recessed installation and why would you use ac90 in a house? Use an 1104 or 1004 with ears and clamps and nmd90. It's better to attach to a stud, but every one seems to be using F clips. The flex bit is good for getting you out of a problem, but it's also great for getting you into one, so be careful. If you can use a flex bit, you must have access above or below so an auger bit will work, too.
The hole for the box is 2.25 inches wide by 3.25 inches high and the side are straight. Notch the bottom for the screw tab so the box can sit on the bottom of the hole. If you can hit a stud, use #6 wood screws. They sit tighter against the side of the box, but the hole must be .25 inches away from the stud or the box will twist out of the wall.
I assume it isn't an outside wall or you wouldn't be thinking about using a mirror; but, if it is, don't forget the vapour barrier.
If the walls are lathe and plaster, just call an electrician.
#193355 - 03/29/1012:21 PMRe: Adding a switch in a finished house
Thanks for the response twh - the reason I would use ac90 is because the line has to be fished through the wall - therefore the line cannot be tacked down - hence the code requires ac90. Thanks for your other tips.
#193366 - 03/29/1002:12 PMRe: Adding a switch in a finished house
I don't think you require ac90 the only rule that talks about fished cable is 12-520.I use nmd90 all the time in walls when I need to add a new addition or extend a cct.Next time I take out a permit I will ask the electrical inspector.Iam in BC so BC safety Authority.
using a 2104 box will do a better job than an 1104 the welded box will sit absolutely flat against the stud and can be screwed into place just bang the drywall tabs flat and cut the hole right flat against the stud.
forgot to add, use a coathanger with a sharpened end. drill throught the flor or ceiling right next to the wall. this will give you a location for drilling your wiring hole from the attic or basement without guessing, and will leave a very tiny hole which you can fill with drywall mud if it's ceiling. and if it's floor you won't even see the hole later.