Fused neutrals

[mbrooke]

Why were neutrals fused in the past? Did code mandate it? And why?

 

[infinity]

How do you know that there was a fuse in the fuse holder and not a solid conductor?

 

[mbrooke]

How do you know that there was a fuse in the fuse holder and not a solid conductor?

At one point it was common that there wasn't. I mean, just here, why would someone go through the trouble of running the noodle through an Edison screw holder?

 

[ptonsparky]

It was very common to have fused neutrals. Many of the services were 30 amp 120 volt. 60 amp 120/240 upgrade came along and the old fuse block was refed or left as it was.

 

[mbrooke]

It was very common to have fused neutrals. Many of the services were 30 amp 120 volt. 60 amp 120/240 upgrade came along and the old fuse block was refed or left as it was.

Did they ever fuse the noodle at 120/240? Seems like a bad idea, even for the time.

 

[synchro]

According to the 1920 National Electrical Safety Code,

"Grounded neutral conductors in three-wire systems shall be arranged without automatic circuit-breakers or fuses interrupting their continuity, unless the circuit breaker opens all conductors of the circuit with one operation.
In two-wire branches from three-wire circuits the conductor connected to the neutral is not for the purpose of this rule considered a grounded conductor."

I think this meant that the neutral could be fused in 2-wire branch circuits.
Apparently they had circuit breakers back then but not for residential applications.

https://books.google.com/books?id=_...issue 2 "grounded neutral conductors"&f=false

 

[romex jockey]

The old carter 3w's switched noodles ,treated like the 'hot'

and one did not see anywhere near modern GE's made off them

the more i think about it, the more i suspect metering problems may have existed

~RJ~

 

[ptonsparky]

Did they ever fuse the noodle at 120/240? Seems like a bad idea, even for the time.

IDR coming across more than two circuits, 4 fuses, in older homes and the open knife switch would have been non fused. The picture you posted would have been found in the business district.

 

[mbrooke]

According to the 1920 National Electrical Safety Code,

"Grounded neutral conductors in three-wire systems shall be arranged without automatic circuit-breakers or fuses interrupting their continuity, unless the circuit breaker opens all conductors of the circuit with one operation.
In two-wire branches from three-wire circuits the conductor connected to the neutral is not for the purpose of this rule considered a grounded conductor."

I think this meant that the neutral could be fused in 2-wire branch circuits.
Apparently they had circuit breakers back then but not for residential applications.

https://books.google.com/books?id=_P...ors%22&f=false

Thanks

But why was it done in the real world? I remember seeing posts where in K&T had fused neutrals, I am positive about this.

 

[mbrooke]

IDR coming across more than two circuits, 4 fuses, in older homes and the open knife switch would have been non fused. The picture you posted would have been found in the business district.

Still in very old homes the neutral was fused in 2 wire circuits, and in this one it looks like they wanted to do the same.

 

[mbrooke]

The old carter 3w's switched noodles ,treated like the 'hot'


~RJ~

GU24 is your friend

 

[ron]

Is it possible the fused neutral was from an ungrounded DC service they may have had originally?

I guess not with 3 blades

 

[LarryFine]

Is it possible the fused neutral was from an ungrounded DC service they may have had originally?

I guess not with 3 blades

DC can use a 3-wire system, too. Imagine two batteries in series with the "center tap" brought out with the lines.

 

[mbrooke]

Is it possible the fused neutral was from an ungrounded DC service they may have had originally?

I guess not with 3 blades

Maybe. But there was a time in history where fusing the neutral was the standard rather then the exception.


Somehow I doubt folks will believe me unless I post pics...

 

[mbrooke]

Click on the smaller ones to enlarge.

 

[mbrooke]

Some more:

 

[mbrooke]

.....

 

[mbrooke]

Courtesy of Sparky480

 

[mbrooke]

....

 

[mbrooke]

Service meter, note the knife blade and fused noodle.