New wiring into old K&T outlet and switch boxes

Posted by Mark G. on November 5, 2008, 12:29 pm

Good morning.

Is it feasible (and does code allow) me to run romex into an existing metal
outlet or switch box designed for knob-and-tube wiring? Or do I need to
install new boxes to replace the original boxes?

Thanks
-Mark

Posted by Steve Barker DLT on November 5, 2008, 4:58 pm

Just run it in there and be done. don't ask, don't tell.

s

> Good morning.
> Is it feasible (and does code allow) me to run romex into an existing
> metal outlet or switch box designed for knob-and-tube wiring? Or do I need
> to install new boxes to replace the original boxes?
> Thanks
> -Mark
>

Posted by Mark G. on November 6, 2008, 12:22 pm

> Just run it in there and be done. don't ask, don't tell.

So what does a professional electrician do with the old electrical boxes
when replacing k&t with romex? Does he run the romex into the old
boxes? Does he tear into the wall and replace the old boxes with
modern boxes? Something else entirely?

Thanks
-Mark

Posted by Wayne Whitney on November 6, 2008, 2:51 pm

> So what does a professional electrician do with the old electrical
> boxes when replacing k&t with romex? Does he run the romex into the
> old boxes? Does he tear into the wall and replace the old boxes with
> modern boxes? Something else entirely?

You can usually replace an older box with a modern "old work" box
without tearing into the wall. The hard part is getting the old box
out, sometimes you have to dismantle/demolish it in place and pull out
the pieces. Then you may need to enlarge the hole slight for the
replacement "old work" box. Be sure to watch your box fill.

BTW, if you are considering extending an existing k&t circuit with
romex, don't do it. Run your new romex branch circuit back to the
electrical panel. An undisturbed k&t branch circuit will often
continue to work OK, but adding modern loads to it will only cause
problems.

Cheers, Wayne

Posted by John Grabowski on November 6, 2008, 4:42 pm

>> Just run it in there and be done. don't ask, don't tell.

> So what does a professional electrician do with the old electrical boxes
> when replacing k&t with romex? Does he run the romex into the old
> boxes? Does he tear into the wall and replace the old boxes with
> modern boxes? Something else entirely?

I would evaluate each situation to determine the best course of action.
First of all I would definitely not tie into an existing K & T system. You
would just be asking for trouble. I'm assuming that you have one of those
old black painted electrical boxes installed now. Sometimes they have
provisions for cable clamps which I can muster from my truck. It would be
necessary to drill and tap a 10/32 hole for a ground screw and scrape the
paint a little for good ground contact. Unfortunately the black boxes also
tend to not have the cubic inches needed for multiple conductors. In some
cases they are installed in wood lathe and plaster walls which can be a mess
to swap out from a wall that is finished. However if the wall is going to
be repaired and refinished I would change out the box. Sometimes the boxes
are a little loose already and some gentle prying will free it completely.

Can you post some pictures?

Page 1 of 3 1 2 3 > last >>

Similar Threads	Posted
New wiring into old K&T outlet and switch boxes	November 5, 2008, 12:30 pm
Plaster/Skim removal from Socket/switch boxes	February 18, 2007, 5:15 pm
Re: switch grounded outlet combo question.	November 19, 2007, 3:20 pm
Re: switch grounded outlet combo question.	November 19, 2007, 4:41 pm
Re: switch grounded outlet combo question.	November 19, 2007, 7:37 pm
buying cabinet boxes	February 14, 2007, 8:52 pm
Electrical Boxes and Lighting	March 23, 2009, 3:52 pm
I'm wondering how much to sell some boxes of ceiling tiles for	May 28, 2007, 1:18 pm
On?off switch for water heater	July 16, 2006, 11:21 pm
Switch-receptacle-fixture?	November 29, 2006, 9:16 am