How would a home built in 1880 be wired for indoor electricity when
electricity became available in the early 1900's assuming all interior
walls are 2 foot thick concrete? I have found that cloth wrapped wire
was used, but how was it placed along the concrete walls of a room?
Via circular ceramic standoffs? Metal eyebolts? Exposed wire? Some
early conduit?

Howdy bl31705-ga,

The wiring done at that time is commonly referred to as "knob-and-tube"
because it mostly used porcelain knobs and tubes to mount and guide the
wires of the time along and through walls.

This online copy of the 1899 National Electrical Code, courtesy of the Mike
Holt Enterprises, Inc. web site, covers the regulations of the early 1900s.
http://www.mikeholt.com/documents/nec/NCSE1899.pdf

"INSIDE WORK.
All Systems and Voltages.
14. Wires ?
...
Must be separated from contact with walls, floors, timbers or partitions
through which they may pass by non-combustible, non-absorptive insulating
tubes, such as glass or porcelain.
...
Must have an approved rubber insulating covering ...
...
Must be supported on glass or porcelain insulators, which separate the wire
at least one inch from the surface wired over, and must be kept rigidly at
least eight inches from each other ..."

If you are doing something that requires accuracy, you should read the above
document in detail.

This Electronetwork site reproduces some pages from the "Hawkins Electrical
Guide," dated 1917, which shows "various porcelain knobs and cleats."
http://www.electronetwork.org/assemblage/zone5/heg.htm

More on wall tubes, plus a good picture of a cleat and a knob can be found
on this "r-infinity" web page.
http://www.r-infinity.com/Wall%20Tubes/index.htm

"Many small electrical porcelain companies sprung up in the early 1890?s
to make wiring insulators."

The "Collecting Insulators" site has some descriptions of various knobs.
http://www.collectinginsulators.com/Knobs/

"House wiring split knobs were popular in the early part of the 20th
century. Manufacturers patented numerous 'improvements' and a large number
of companies entered the market to meet the huge need to electrify homes."

This "Helter Shelter" article by Walter Jowers describes running across a
house that still had "knob-and-tube" wiring.
http://www.aceweekly.com/Backissues_ACEWeekly/2003/030731/heltershelter030731.html

"... the rubber-and-cloth insulation is usually brittle and crumbling,
leaving little patches of bare naked hot wires exposed."

So, a house of the type you describe, probably would have had cloth covered
rubber coated wiring.  It would be mounted on porcelain knobs, probably run
from the top of the wall, down the wall to a plug or a switch, and back up
the wall to run to the next section of the circuit, such as a light, etc.

When it reached a wall, there would be a tube that ran through the wall,
and the wire would go through that tube to the other side of the wall.  At
places, the wires might have been separated with the cleats mentioned above.

The cleats and knobs would have most likely been attached to the wall with
nails, or maybe even "spike" type nails in the case of a concrete wall.

The following are attic, etc. installations, but show typical "knob-and-tube"
electrical runs.

On "The Old House Web" site.
http://www.oldhouseweb.com/stories/Detailed/10327.shtml

Walton EMC web site.
http://www.waltonemc.com/Newsletter_Archive/2002_11November.htm

If you need any clarification, please feel free to ask.


Search strategy:

Google search on: knobs house wiring 1890..1910
://www.google.com/search?q=knobs+house+wiring+1890..1910

Google search on: "knob-and-tube"
://www.google.com/search?q=%22knob-and-tube%22

Google Images search on: "knob-and-tube"
http://images.google.com/images?q=%22knob-and-tube%22

Looking Forward, denco-ga - Google Answers Researcher

---

Request for Answer Clarification by bl31705-ga on 21 Sep 2005 08:28 PDT

Just a tiny clarification. You're right about everything. You say the
wire is mounted on porcelain knobs, but how? I've driven myself nuts
searching for an installed example. There are clamp-type porcelain
insulators (duh!) but then there are the knobs. Is the wire wrapped
around the knobs or is the wire placed in the groove of the knob and
attached with something else, like a wire to hold it to the knob?
You're a great help!

---

Clarification of Answer by denco-ga on 21 Sep 2005 16:22 PDT

Howdy bl31705-ga,

The example shown here, from my answer, shows the "two piece" knob
style in place.
http://www.oldhouseweb.com/stories/Detailed/10327.shtml

It was not atypical, as the comment inidicates, for wires to be run inside
former gas lines, but it was also not unusual for a house to have both
electricity and gas installed.

In those cases, the house, if done to "code," would have, as indicated by
the 1899 NEC, rubber coated wire and the wires going from knob to knob,
and exposed.

"e. Must be kept free from contact with gas, water or other metallic piping,
or any other conductors or conducting material which they may cross, by
some continuous and firmly fixed non-conductor, creating a separation of
at least one inch. Deviations from this rule may sometimes be allowed by
special permission.

Placing the wiring in gas pipes was actually against "code" at the time.

Also, the "tubes" were not used on the walls, but only when passing through
walls.

In the rural part of Illinois, where I grew up, I saw, as a youth, several houses
that were wired exactly as I have described.

Looking Forward, denco-ga - Google Answers Researcher

The answer put me in the right direction. A+

I have personally worked with wiring of that vintage, mostly in the
restoration of trolley cars.  But I have also worked with old houses
and have observed the following:

In the city of Chicago, all wiring was done inside piping.  In houses
that had gas lighting they would typically use the old gas piping. 
The junctions were done in cast iron boxes with threaded bosses in
them.  These boxes were about 3 inches in diameter and the wires would
be CRAMMED into them.  In houses where wiring was new, they still used
threaded pipe, exactly the same size as plumbing pipe--typically 1/2
nominal schedule 40.

In the suburbs knob and tube was allowed--BUT!!!  Knob and tube wiring
had to be in places normally inaccessible to the occupants.  So, it
would be inside the walls and in the attics.  You asked how the knobs
worked.  Well, they typically are two pieces of ceramic and a nail or
screw down the middle.  Many of the pictures mentioned in the answer
show this.  You laid the wire between the two pieces (which had a
groove in them) and tightened the fastener.  Be really careful when
using a hammer!

Better protection was required for exposed wiring.  You asked about a
concrete house, so everything would have to be mounted on the walls. 
They would use standard pipe and those boxes I mentioned above.

Incidentally, the cloth-covered wires were really a little more than
that.  The cloth was impregnated with what we called asphalt.  Really
it was gilsonite, which was not acidic and would not degrade the
cloth.  It would melt at low temperatures, not much more than 140 F. 
Furthermore it would get brittle with age and elevated temperatures. 
I have removed wiring from trolley car lamps and found the wire
brittle for about 6 inches;  beyond that the wire looked in perfect
condition.

So you're saying that rather than knobs and tubes, piping was used
along interior walls? That makes more sense than exposed knob and tube
along walls. I wanted to know how it would have been placed along the
concrete walls of a room, not behind the walls or in the attic as knob
and tube would have been used. Have you ever seen knob and tube used
on the interior of a room?

Thanks for the 5 star rating and kind comment, bl31705-ga.

It was my pleasure.

Looking Forward, denco-ga - Google Answers Researcher

In the few houses that I have seen, they NEVER had knob & tube on the
outside of the walls.  And, especially in those early days where they
really knew that the flexible insulation was short-lived, I cannot
conceive of it having been used.

Now houses were not really wired until after the start of the 20th
century.  Many houses had single lights on the ceiling and the switch
operated by a pull cord, and it is remotely possible that surface knob
& tube were used then.

As for wall mounting, unless they added protection afterwards, it
almost certainly would have been in pipe.

That said--look up some information on Tom Edison's laboratory and his
early wiring ideas!!!