Fuse panel change with arc faults

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
I don't think the open fuse would cause the voltage problem. Each were most likely two wire circuits with no shared neutrals. That is bigger than what I've seen locally but those original installs were done well. Workmanship was top of the line. It wasn't until handyman or homeowner Joe got involved did things go downhill.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Looks like the neutrals have their own fuse holder, placed above each energized line circuit.
I don't know about that. If you read the "directory" written by the top right block, there seems to be separate circuits for each of the right and left upper and lower fuses.

If I didn't know better I would almost say that this was a three phase panel wire as single phase. The neutrals were spliced together elsewhere.

-Hal
 

ramsy

Owner/Operator
Location
LA basin, CA
Occupation
Service Electrician 2017 NEC
"directory" written by the top right block, there seems to be separate circuits for each of the right and left upper and lower fuses.
Both fuses may be same circuit. It is common for bathrooms in older homes to share the same circuit with other rooms in the house.

If I didn't know better I would almost say that this was a three phase panel wire as single phase. The neutrals were spliced together elsewhere.
Yes, if 3 fuses on each block, rather than 4. Also, it was common practice to fuse the neutral at residential services prior to 1940's
 

bzzt

Member
Location
mn
Occupation
wirer
Neutral runs up the middle I believe. This could be changed out if that’s the case to afi/gfi breakers!


Sent from my iPhone using Tapatalk
 

ramsy

Owner/Operator
Location
LA basin, CA
Occupation
Service Electrician 2017 NEC
So in this case, a penny in each of the two top fuse holders would make this "more" code complaint. :sneaky:
After laborers do kitchen & bath remodels, with SABC's tied to the same switched neutral, those old neutral fuses save it from burning down.

90.1(B) defines inadequacy of Code against future monkey business, and fused neutrals are by design for this economy of labor exploit, and the politics of defunded regulators.

Unless of course the panel flipper's 200A upgrade on existing #10 service conductors burn it down first.
 
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kwired

Electron manager
Location
NE Nebraska
Bottom two blocks in the photo are inverted from the top ones, neutral is likely the bottom fuse on those.

Yes most every time I have seen this type of fuse block they fused both grounded and ungrounded conductors of the circuit(s).

Keep in mind some those installs were done before there was a utility company serving the premises and maybe was no grounded conductor at all at that time.
 

Frank DuVal

Senior Member
Location
Fredericksburg, VA 21 Hours from Winged Horses wi
Occupation
Electrical Contractor, Electrical Engineer
On each 4-fuse block, 1st open neutral could create an MWBC, the 2nd open neutral could create Line-Line Voltages
No. The neutral is just not connected in that particular circuit, so no current flows. It is just two wires in that circuit, no MWBC.

The reason fused neutrals were written out of code was because "the light is off so the circuit is dead, safe to work on" or "I used a meter between the hot and neutral wire, no voltage measured, safe to work on", as the person holds the still hot wire in their hands standing on the aluminum ladder sitting in water on concrete floor.... or leaning against a porcelain sink/tub with chips.

Dual fuse plugs were common back in the 60s to add to equipment. Hmm, still are on Christmas Lights! :unsure:

Two of those pictured fuses are OLD. They haven't made those black ones for 60+ years.
 

ramsy

Owner/Operator
Location
LA basin, CA
Occupation
Service Electrician 2017 NEC
The reason fused neutrals were written out of code was because "the light is off so the circuit is dead, safe to work on"
We have a historic Placentia, CA neighborhood with 1920's bungalows still using fused neutral only at service disconnect.

The POCO line goes directly thru unfused to ceiling keyless pull-chain lights, where original-owner occupants run extension cords from screw-shell adapters.

I don't know if that was code at turn of century, or a later hack, but owner would not allow 100A replacement disconnect per code.

All I could do was cut the line, call POCO, and leave it in their hands.
 

brycenesbitt

Senior Member
Location
United States
Here's another one like that.

The top fuses are the hots, the bottom fuses are neutrals.
On the feed, the neutral line runs up the middle.

PXL_20210409_201135422.jpg

So that's four separate circuits with fused neutrals.

The issue with changing this particular one is the rule about closets.
Around here, just about every electrical panel is in a closet. When I inspect apartments, the closet is where I look first!
https://www.ecmag.com/section/codes...trical-and-service-panels-residential-closets
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Is it just me or do I see 15, 20s and what I think is one 30A fuse on wire that’s all the same size?
Anything is doable, how much money is the question. And getting that panel junked is going to be a lot of trouble if it’s done right with the abatement & containment costs.
Original knob and tube installations were permitted to use the free air ampacities, so that would permit a 30 amp fuse on 12 AWG copper.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Looks like the neutrals have their own fuse holder, placed above each energized line circuit.

On each 4-fuse block, 1st open neutral could create an MWBC, the 2nd open neutral could create Line-Line Voltages
They are all two wire circuits with fused neutrals.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I don't know about that. If you read the "directory" written by the top right block, there seems to be separate circuits for each of the right and left upper and lower fuses.

If I didn't know better I would almost say that this was a three phase panel wire as single phase. The neutrals were spliced together elsewhere.

-Hal
Fused neutrals were very common in the day of knob and tube, but 120/240 volt systems were not very common for dwelling in those days. The typical service for a dwelling was a 30 amp, 120 volt service.
 

brycenesbitt

Senior Member
Location
United States
Original knob and tube installations were permitted to use the free air ampacities, so that would permit a 30 amp fuse on 12 AWG copper.
Yes correct.
And this panel is just fine in that respect.
Replacing the four neutrals with 30's and the hots with 15 mini-breakers would pretty much do it.
The high ampacity loads such as the kitchen are already modern wire.

Those who think that K&T has a heat problem have never really thought it through. Fusing this 12 k&t wire down
to 15 amps leaves plenty of margin, including for insulation over the top.
 
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