Knob&Tube Puzzle-Neutral Fused?
I still have some Knob & Tube in service in my house.
Old, but ‘modern’ enough to have rubber and cloth insulation on it.
I’ve always been curious why they fused both the Hot AND the Neutral on these circuits. Not just in my house- this practice appears to be relatively common around New England.
So what were the dead men thinking here?
Back in those days the concept of "neutral" was fairly vague. There were two wires coming into the house, and often no real rule as to which one was "neutral" and which one was "hot" (nor an assurance that that relationship would remain constant over time). I suspect that in some cases "ground" potential was actually about midway between the two wires, or the wires were allowed to "float" relative to ground. And even if the "neutral" coming in from outside was reasonably well-defined, there were few guarantees that the wiring inside would maintain that relationship. (Plus, fuses likely weren't all that reliable either.)