New wiring into old K&T outlet and switch boxes

Posted by Mark G. on November 6, 2008, 5:43 pm

> Can you post some pictures?

Here is what the beasts look like:

http://rainchain.drizzlehosting.com/electrical_box

Posted by Bobk207 on November 7, 2008, 3:37 am

> > Can you post some pictures?

> Here is what the beasts look like:
> http://rainchain.drizzlehosting.com/electrical_box

Box fill can be a problem. The old K&T switch boxes are not even
rectangular and really don't have much room.

I've replaced more than a few of those boxes without destroying the
wall locally. It's a bitch but doable with a die grinder or a Dremel
(with fiber cutting wheels) or a Roto-Zip but imo worth the effort to
not damage & require repair of the finished wall. With a little
practice you can actually do it and have the work easily be covered by
the switch plate.

One problem in my old house is often the boxes were set too close to
doors and the door molding eclipses part of the box...I guess in 1930
electricity was kinda new and the electricians didn't allow enough
room for the trim, so I've had to move over about 1" (remove &
replace, actually) about 1/2 of the switch boxes (about 10) .

then I just use as deep a tiger box I can find or I back screw mount
& SIKA epoxy bond a standard new work switch box (single gang) usually
again a DEEP one..... the fill capacity of a standard cross section
and deep box is much better than a tiger box, plus GFI's and dimmers
fix better.

I've removed almost all of the K&T from my 1930 house and I'm still at
a loss as to why some guys are SO afraid of the stuff.

In every run I've removed the insulation has been soft and slick and
compliant ....even the stuff in the attic. Only in the switch boxes
(and the occasional ceiling light box) at the stripped ends have I
observed any insulation deterioration and this was only the last inch
or so........easily fixed with a few inches of heat shrink tubing when
necessary. IMO good to go for another 20 years at least. The copper
conductors appear to be tin plated as well.

A 20 amp breaker feeding 12 gage wire should be just fine to add onto,
not that I've done it...my house is now nearly all EMT or flex with 12
gage THHN/THWN stranded.......but why the concern about K&T ?

I've seen houses from the 50's where the first generation (?) Romex
(black sheathed paired black & white with ground) is in much worse
shape than my nearly 80 year old K&T.

cheers
Bob

Nice floor tile.....anyone know where to get stuff like it today?

Posted by HerHusband on November 7, 2008, 10:15 am

Bob,

> I've removed almost all of the K&T from my 1930 house and I'm still at
> a loss as to why some guys are SO afraid of the stuff.
> In every run I've removed the insulation has been soft and slick and
> compliant ....even the stuff in the attic. Only in the switch boxes
> (and the occasional ceiling light box) at the stripped ends have I
> observed any insulation deterioration and this was only the last inch
> or so........easily fixed with a few inches of heat shrink tubing when
> necessary.

I rewired my in-laws house last year, and my experience was completely
opposite of yours. They have a 100 year old house, though I don't know how
long the K&T wiring has been in the house. It seemed to be a later
addition, followed by several "updates" over the years. A real show case
for the various electrical technologies of the past several decades. :)

With very few exceptions, the insulation was dry and brittle, with many
wires being completely uninsulated and exposed. It was a miracle the house
didn't burn down from all the burnt and corroded terminals, or that someone
didn't get electrocuted from the uncovered bare wires in the basement.

Even the "newer" cloth covered cables were in really bad shape, though the
rubber insulation on the individual wires seemed to be mostly in good
shape.

The rusted fusebox with the exposed main knife cutoff switch looked like
some kind of ancient torture device. Rust, burnt terminals, broken
insulators, etc. Scary! :)

Anthony

Posted by John Grabowski on November 7, 2008, 9:08 am

>> Can you post some pictures?

> Here is what the beasts look like:
> http://rainchain.drizzlehosting.com/electrical_box

Obviously those will not pry out as easily as I originally thought. Some
damage may have to be inflicted to the wall. As someone else suggested,
careful cutting with a Dremel or Rotozip will make a cleaner opening.
Because of the bevel back corners those boxes don't have the cubic inch
capacity needed for multiple conductors and a device.

Posted by Bill on November 7, 2008, 4:22 pm

I second the RotoZip.
I just helped someone cut A/C vents in really old plaster with lath. Cut 9
vents, but went through as many bits.
The RotoZip did a great job. It even has an attachment for a vacuum.

>>> Can you post some pictures?

>> Here is what the beasts look like:
>> http://rainchain.drizzlehosting.com/electrical_box

> Obviously those will not pry out as easily as I originally thought. Some
> damage may have to be inflicted to the wall. As someone else suggested,
> careful cutting with a Dremel or Rotozip will make a cleaner opening.
> Because of the bevel back corners those boxes don't have the cubic inch
> capacity needed for multiple conductors and a device.

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New wiring into old K&T outlet and switch boxes - Page 2