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Knob & Tube...circa 1924

03:36AM | 02/22/00

Member Since: 02/21/00
1 lifetime posts

Knob & Tube...circa 1924

I just bought a old 2-story colonial (1924), and about 35% of the wiring is knob & tube. After reading a little about it, and examining it in the basement, I want to get rid of it. Most of the remaining knob & tube is on one circuit breaker that feeds a line that runs the length of the house.

It looks like it feeds most of the outlets in the LR, DR, and probibly the ceiling lights, and the upstairs BRs.

I figure I can fish new wire up through the basement for the outlets on the first floor, and I can feed down through the walls from the walk-up attic for the second floor. My PROBLEM is the three ceiling fixtures (on wall switches) on the first floor.

How does one replace the wiring in these? I was thinking about tying a string to the old wire when I pull it out, and using that string to fish new wires. HOWEVER, I do not know if they used the "tubes and knobs" in the walls and in the ceilings...the ceramic tubes would make this very difficult. Will I have clearance to pull the new wire through?

Anyone? Thanks.

Joe Tedesco

04:22AM | 09/29/02

Member Since: 07/27/02
141 lifetime posts

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[This message has been edited by Joe Tedesco (edited April 09, 2003).]

motor-T

04:00AM | 09/30/02

Member Since: 09/27/02
9 lifetime posts

The ceiling will have to be cut into to refeed the fixtures. The problem with knob and tube is you can have one wire coming in from one direction and the neutral(grounded conductor) coming in from the other.
As far as replacing all of the K & T it may be extemely difficult to do.
Some insurance companies will not issue a policy if the house is wired wiht K & T, one problem was and now is the blown in insulation especailly on the exterior walls, where the wire is run to go to the second floor.
Knob and tub by itself was not a bad system and worked well, it just wasnt expected to supply the numerous loads we have today.
that said, you might want to check it first to see if it really needs to be replaced especially in the ceilings, those few lights may well be ok with the current system, as long as you reduce the other loads laundry refrigerator &c.
But add new small appliance circuits for the kitchen, Refrigerator circuit, laundry circuit, this will help alleviate most of the heavy loading on the old system. These suggestions are intended if you have the space in the service panel to locate the new circuits.
Mark

Electrical Inspector

02:26PM | 09/30/02

Member Since: 09/27/02
76 lifetime posts

Right on Mark.

you could have some switched receptacles in the LD & DR.....

or you could ( as Mark alludes) take all possible load off the leg of K&T that does the cieling fixtures, disconnect the fixtures, megger the remaioming cuircuit out to establish some integtrity.

reduce the fuse/breaker size to less than normal ( basically derate for age & wear)

rebox the fixtures with 'old work octogons', prefereably plastic.

add 90 deg pigtails to the K&T

find new lighting fixtures of a plastic variety, or basically something that does not require grounding.

there are also some specialty breakers that would enhance the safety of the older circuit.

this may all sound extensive, but whatever you choose please get back to us, there are members that can address specifics for you.

good luck.