Re: Knob-and-tube wire guages
Stamcom,
That
is interesting. The most common configuration I find will have two original 120 volt, 15 amp branch circuits. One circuit will supply the lighting of the dwelling, and the other will go to a three gang box in the kitchen that houses a snap switch, on-indicator light and single receptacle. If the building is somewhat larger than the average modest dwelling, another 15 A lighting circuit will have been installed. All of this is knob & tube, or, infrequently, black rigid conduit.
Over the decades following the original installation, extensions are added, most commonly to the lighting circuit(s), and most commonly using BX (old style armoured cable). Once that is overloaded, the second circuit is gotten to and extended.
Sometime along the way, the coal furnace gets upgraded to oil or natural gas, and a new 15 A 120 V circuit gets shoe horned into the original fuse center, and as a rule, this circuit gets no extensions added to it. (People up here seem to intuitively understand the value of protecting the heat source from nuisance trips
).
20A 120 V branch circuits start showing up when the original 30 A service is upgraded to 60 A (1930s thru 1950s work, required locally to be "all metal" - BX, EMT, flex, etc.) and predominantly go to the kitchen, but may have the laundry tacked on as well. (It wasn't until later that adding a seperate laundry circuit to an existing electrical system became a local requirement).
In your experience, what loads are the 20 A knob & tube circuits in your area supplying?