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Posted By: Davo Adding a switch in a finished house - 03/27/10 05:36 PM
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
Posted By: Rewire Re: Adding a switch in a finished house - 03/29/10 04:50 AM
why would the hole need to be large or messy I have installed hundreds of oldwork boxes that wshen complete are completly hidden
Posted By: twh Re: Adding a switch in a finished house - 03/29/10 05:32 AM
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.


Posted By: Davo Re: Adding a switch in a finished house - 03/29/10 04:21 PM
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.
Posted By: jackolsen Re: Adding a switch in a finished house - 03/29/10 06:12 PM
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.
Posted By: Davo Re: Adding a switch in a finished house - 03/30/10 06:26 PM
Well that settles it. Thanks for that 12-520 jackolsen.
Posted By: homerjones Re: Adding a switch in a finished house - 03/31/10 09:09 AM
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.
Posted By: homerjones Re: Adding a switch in a finished house - 03/31/10 09:13 AM
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.
Posted By: frank Re: Adding a switch in a finished house - 03/31/10 01:16 PM
I have no idea what the code rule is but 9c90 is required for rework the rational is dragging a cable through a void can skin it.i know this because of the inspector busted me on it.
Posted By: Alan Belson Re: Adding a switch in a finished house - 03/31/10 01:25 PM
Could you not go wireless? A tx-rx will probably cost less than the labour involved all that drilling and fishing. Especially if you damage the customer's wall finish!
Posted By: twh Re: Adding a switch in a finished house - 04/01/10 03:39 AM
Quote
I have no idea what the code rule is but 9c90 is required for rework the rational is dragging a cable through a void can skin it.i know this because of the inspector busted me on it
I hope that's an Ontario rule.

Quote
Could you not go wireless?
I'd like to learn more about that. Can someone provide a link?
Posted By: mikesh Re: Adding a switch in a finished house - 04/01/10 06:02 PM
I would like to know where it is required to use bx when wiring is fished? The BX cable can do a lot of damage to loomex when it is fished into a cavity where loomex is.
If anything we would actively discourage it and i might even require a contractor to open a wall to prove the bx did not damage loomex already there. A loomex cable sliding across another in the wall is no where near the risk that pulling a bx in would create.
Now if loomex is installed in a T-Bar ceiling we require the drop from the ceiling to the fixture in the t-bar to be wire with bx so that when a guy comes to install a bunch of data wire he won't damage the fixture drop wires. Not much loomex gets installed in tbar ceilings since most t-bar ceilings are used to move air which requires an ft-4 rating and I believe loomex is only ft-1.
Posted By: Alan Belson Re: Adding a switch in a finished house - 04/01/10 09:11 PM
I get stuff online from a UK electrical wholesaler.

Here's a similar US operation, http://www.foxelectricsupply.com/

- you should be able to locate a similar Canadian business.

Here's a maker: http://www.illumra.com/

Or, Google: "wireless light switches"

Alan

Posted By: dougwells Re: Adding a switch in a finished house - 04/23/10 06:58 PM
Originally Posted by mikesh
I would like to know where it is required to use bx when wiring is fished? The BX cable can do a lot of damage to loomex when it is fished into a cavity where loomex is.
If anything we would actively discourage it and i might even require a contractor to open a wall to prove the bx did not damage loomex already there. A loomex cable sliding across another in the wall is no where near the risk that pulling a bx in would create.
Now if loomex is installed in a T-Bar ceiling we require the drop from the ceiling to the fixture in the t-bar to be wire with bx so that when a guy comes to install a bunch of data wire he won't damage the fixture drop wires. Not much loomex gets installed in tbar ceilings since most t-bar ceilings are used to move air which requires an ft-4 rating and I believe loomex is only ft-1.


12-612 Proximity to knob-and-tube and non-metallic-sheathed cable systems

Where armoured cable is used in a building in which concealed knob-and-tube wiring or concealed non-metallic-sheathed cable wiring is installed, the cable shall not be fished if there is a possibility of damage to the existing wiring.
Armoured cable must not be fished in locations where concealed knob-and-tube wiring or non-metallic-sheathed cables have been installed. The armoured cables may damage the insulation on the conductors or cables, causing arcing or shorting and creating a potential fire hazard or loss of power to circuits or equipment.



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