knob and tube

[billdozier]

Hey guys went to an older building today which had been remodled in the 70s? The older electrician and I were talking about these old buildings and that they had probaly wired originally in k&t. My question is how would risers have been run back in the day. This building although it had several panels with multi riser pipes feeding these subpanels. Was fed from one MDP. How were these buildings typically originally wired? Was it all k&t back in the day?

 

[peter d]

In my observations, on really old work they used RMC for conduit runs/feeders, and then K&T for the branch circuits.

 

[winnie]

I used to rent space in an old mill building in Waltham, MA.

For many years now the building has been divided up into multiple tenants, each with their own services, with all wiring in conduit. I saw no evidence of small K+T circuits.

However going up the wall outside of the elevator shaft there were two large diameter cloth covered cylinders; they looked like single conductors covered in loom, but at least 1.25" in diameter, perhaps 1.5". These were supported by porcelain clamps; squares of porcelain clamped by bolts at the edges with holes in the center to grab the cables.

I could not be sure that this was old wiring, but the first time I saw it my assumption was that this was some sort of high current feeder for K+T.

-Jon

 

[charlie]

. . . going up the wall outside of the elevator shaft there were two large diameter cloth covered cylinders; they looked like single conductors covered in loom, but at least 1.25" in diameter, perhaps 1.5". These were supported by porcelain clamps; squares of porcelain clamped by bolts at the edges with holes in the center to grab the cables. . .

I'll bet it was DC for running the elevator. :smile:

 

[charlietuna]

Knob and tube was used throughout the entire building. Usually had one panel in the first floor or basement and then vertical up thru the walls into the attic and then horizontal. Remember, back then there wasn't a need for many circuits,mainly lighting. you would be suprised to see some of the loads those old circuits carried!! Not long ago we did a blast freezer for a military base and they called for knob and tube in the freezer.

 

[dezwitinc]

Here is an excellent paper on K&T by Mark Heller of Heller Electric which I believe is located in San Francisco.
http://www.markhellerelectric.com/wusplice.pdf

 

[al hildenbrand]

How were these buildings typically originally wired? Was it all k&t back in the day?

As with today's work, . . . it depends.

I've worked in a lot of buildings, single & multi family & commercial, that have had K&T still in service. The K&T has been, in one unusual case, pristine as installed in 1910, and all the rest has been in various stages of change brought on by remodeling and electrical upgrades.

What I have observed, archeologically speaking, is that sometimes the electrician mixed different wiring methods, and sometimes not.

Sometimes there were subpanels and sometimes (mostly) not.

Sometimes there were individual meters for multiple tennants, sometimes not.

It seems that, if the customer could pay for a better wiring method, and wanted the better wiring method, then he got it.

In my Metro Area, there are several jurisdictions that have legislated "all metal" codes that excluded, for a couple decades, the installation of nonmetallic wiring methods. The buildings in these jurisdictions offer additional insights into the history of "what the original electrician did".

I have learned that bidding, on electrical changes that requires altering existing K&T that is enclosed in finished walls and ceilings before I do the work, is almost impossible to be accurate on. One has to include escape clauses for the K&T alteration that starts sucking time.