Fused Hot and Neutral Old K&T

Joethemechanic

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
I used to see this a lot years ago, seemed like I mostly saw it in outbuildings with maybe a single circuit. Square metal box with a little porcelain Edison based fuse holder, 2 plug fuses and both the hot and neutral fused. I just saw one the other day in an abandoned farm building. Did the code ever allow this? What was the reasoning behind having a fused neutral?

Fuse holder like this for 1 circuit "110" in a metal box with a hinged lid. I used to see them everywhere like 50 years ago

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I think it had to do with many older systems having a non-grounded neutral conductor. You never knew what might fault to what.
 
I believe it was the 1925 NEC 805 d. "No fuse or circuit breaker shall he placed in any permanently grounded wire, except a circuit breaker which simultaneously opens all conductors of the circuit and except as provided in sections 807 and 808 of this Code."
Same year they required polarized lamp holders
206 e. "Polarized terminals: All devices provided with terminals for the attachment of wires and intended for connection to more than one side of the circuit shall,unless specifically excepted, have a pair of connecting terminals properly marked for identification, unless the electrical connection between the pair of terminals intended to be connected to the grounded conductor is clearly evident. This requirement shall become effective April 1, 1926."

In this era there was not much of a grid so systems were who knows, ungrounded 110V DC was common as was 32 Volt home generators on farms. It was not until after WW2 that the west coast got all on 60HZ.
You probably know better than me but appliances back then were deisgned for 110 AC or DC operation --- 'universal motors'
I have seen a older welder/generator that had a standard receptacle marked '115V DC'.
 
tortuga said:
I have seen a older welder/generator that had a standard receptacle marked '115V DC'.
Click to expand...

Lincoln SA200 "Pipeliner" They are still a highly desirable machine. This one in the vid is a 1953 "Short Hood". Having a Short Hood on a pipeline job is like having a 57 Chevy convertible. You are "The Man"


Screenshot 2025-09-03 164229.png

I have a "Red Face" SA200. Pretty much the same machine but with a longer enclosure. Both machines have the earlier copper wound generators and exciters. Very desirable stick welding characteristics. Smooth like silk

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1960's era "Red Face"
 
It would be cool to see a video of someone with a 15A 120V DC circuit off a genny like that or some batteries test a bunch of modern stuff on a 120 DC receptacle.
Most things would probably just emit smoke, would a standard LED lamp work?
Universal motors would work.
In theory those cheap switch mode power supplies in cell phone and laptop chargers *might* work.
Resistance heaters would work...
 
tortuga said:
It would be cool to see a video of someone with a 15A 120V DC circuit off a genny like that or some batteries test a bunch of modern stuff on a 120 DC receptacle.
Most things would probably just emit smoke
Click to expand...
Why do I have the feeling Mehdi Sadaghdar (better known as ElectroBOOM) has already done this?
 
We had one at our shop that was the electric version of those machines driven by a three-phase motor driving the welder generator. It didn't get used too much but they sent it out to a job to use it once and had the electrician on the job wire it up. This thing welded great at the shop.

But they called our shop and said it wasn't working right.

Turns out he had the rotation wrong
 
LarryFine said:
I think it had to do with many older systems having a non-grounded neutral conductor. You never knew what might fault to what.
Click to expand...
Whatever time they changed it was done uniformly because neutrals for lighting were universally ‘switched’ with K&T. There had to be a plan somewhere to get the old 32 volt DC wiring to work with the new fangled 110. The house we grew up in had glass batteries in the ‘basement’.
 
ptonsparky said:
Whatever time they changed it was done uniformly because neutrals for lighting were universally ‘switched’ with K&T. There had to be a plan somewhere to get the old 32 volt DC wiring to work with the new fangled 110. The house we grew up in had glass batteries in the ‘basement’.
Click to expand...
Screenshot 2025-09-03 214337.png
 
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