# What is it? #395 : Branch circuit panel



## derekleffew (Mar 15, 2011)

What is it (#395)?


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## JohnHartman (Mar 15, 2011)

derekleffew said:


> What is it (#395)?


 

Wow.... Now that is real nice.


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## headcrab (Mar 15, 2011)

A live front split-phase panelboard? I notice that there are no knife switches with poles connected across the outer two feed lugs, and thus is unlikely to have been used for three phase.


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## CSCTech (Mar 15, 2011)

Looks like a potentially dangerous switch board of some kind 

Almost looks like a standerd screw base light bulb connecter on each terminal.

I have no clue


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## avkid (Mar 15, 2011)

CSCTech said:


> Almost looks like a standerd screw base light bulb connecter on each terminal.


 Those sockets can accept more than just lamps.


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## Van (Mar 15, 2011)

I sure as heck wouldn't go putting my tongue on it !


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## MPowers (Mar 15, 2011)

May I post a reply?


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## derekleffew (Mar 15, 2011)

MPowers said:


> May I post a reply?


It depends.

> The intent of this forum is to be educational, directed at students. Unless specifically stated otherwise, professionals should not answer (but may kibbitz) until at least one week from the time of the original post.


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## MPowers (Mar 15, 2011)

Didn't see a "not to" in the OP, so I thought I'd ask. I actually used one of these in the late 60's, but not for it's original intended use. I'll touch on that next week.


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## CrazyTechie (Mar 15, 2011)

Could it be an older 3 phase breaker panel?


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## zmb (Mar 15, 2011)

Split phase fuse panel using screw-in fuses with screw terminal connections for the circuits and an on/off switch on each circuit?


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## BrianWolfe (Mar 16, 2011)

I used one of these back in the early 60's.


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## chausman (Mar 17, 2011)

A very scary looking fuse panel?


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## derekleffew (Mar 17, 2011)

Which is the neutral bus, and why does it contain fuses?


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## derekleffew (Mar 17, 2011)

[This response was previously hidden. Revealed 03/22/11.]

From http://www.codecheck.com/cc/wiring_history.htm#fusedneutral :

> NEUTRAL FUSES (from the 1915 NEC)
> 
> 
> Rule 23a specifies that a (fuse) must not be placed in any permanently grounded service wire.
> ...


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## zmb (Mar 17, 2011)

derekleffew said:


> Which is the neutral bus, and why does it contain fuses?


 The neutral bus is the middle bar. No idea why it would fused however.


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## chausman (Mar 18, 2011)

zmb said:


> The neutral bus is the middle bar. No idea why it would fused however.


 
Fail safe?


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## BrianWolfe (Mar 18, 2011)

[This response was previously hidden. Revealed 03/22/11.]

The middle shared bar. And it is easier to quote than try to explain:

Putting fuses in the neutral was done away with in the early 1900s. I believe it is closely related to the expanding uniform practice of bonding the neutral to other conductive systems (water pipe, steel, etc.) and to earth, as the local voltage stabilization problems of AC transmitted over long distance was studied and understood.

The shared, or common, neutral of the standard 240 / 120 Volt single phase AC service, has its origin in DC. This multiwire circuit was, and still is, called an Edison Circuit. Thomas Edison's power distribution scheme required lots of small 240 /120 V generators located no more than a quarter mile from the most distant load. DC transformers were not economic or practical.

Until 1900, it was common for the generators to be supported on beds that were monitored to maintain isolation from earth or other conductive systems. Whether to ground the generator, or not, was a design choice.

The early National Electric Codes were written including rules for ungrounded generator frames.

For an ungrounded generator customer, if a neutral conductor on a branch circuit shorted to ground, and there were other shorts of hots (from the same generator) to ground elsewhere in the system, the greatest current would occur in the neutral, the fuse would clear, and trouble would be indicated, and, presumably, the electrician would be brought in.


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## MPowers (Mar 25, 2011)

Earlier I mentioned that I had used one of these before, but not in the intended way.

It was at a small theatre in Myrtle Beach back in 1969. An old 100 seat movie house converted to a community theatre. Everything in the place was DIY by some volunteer. Some how they had managed to get 3 phase power into the building and at some point someone had rewired the device in question to be a 3 phase fuse panel. All the legs shown were hot and the neutral was a separate neutral/ground buss bar next to the "main" The "Main" was a large, 3 pole cartridge fuse, knife switch. Not that unusual a home made device then, especially in areas away from major metro areas.


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## BrianWolfe (Mar 27, 2011)

Imagine the neutral leg trips and you go in to make a repair thinking that there is no power to either leg. That is why they stopped fusing the neutral.


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## tjrobb (Mar 30, 2011)

Looks like the pint-size version of what used to feed power to our offices - ours had a total of 96 fuses (all but ~6 were screw-in). I think I have a photo of it on a thread I started.


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