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Protecting old fuse panels with 20amps? #202662 08/17/11 11:14 PM
Joined: Sep 2006
Posts: 152
C
crselectric Offline OP
Member
When was it practice to upgrade service, and protect old 120volt subpanel feeders with 20amp 1 pole, and leave 20-25 amp fuses in the screw shells, some with 14ga. wire. And that was Ok? I've seen dozens of places in the SF bay area? shouldn't I put in 15 type s fuses?

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Re: Protecting old fuse panels with 20amps? [Re: crselectric] #202663 08/18/11 03:30 AM
Joined: Jul 2004
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G
gfretwell Offline
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Yes. Using anything but 15a fuses on a general purpose 14ga circuit is wrong.


Greg Fretwell
Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203480 10/02/11 08:11 PM
Joined: Mar 2007
Posts: 101
M
mikethebull Offline
Member
In Southeastern New England it is very coommon to see a stack of pennies in the fuseholders of a "main range and floor" 60 amp service for a 3 to 6 apartment .

Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203483 10/02/11 09:08 PM
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Posts: 152
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crselectric Offline OP
Member
what are your thoughts on the mini-fuse breakers, they are ul listed?

Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203492 10/03/11 11:16 AM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
Member
I like the Edison-base breakers, and, yes, they are UL listed for protecting branch circuits.

They are manufactirered by Miniature Breaker, and distributed by Bussmann. Ironically, Bussmann makes them a bit hard to find in their catalog, and even the local Bussmann rep was not aware of their existance. Look for them at your local home center.

One detail to watch: technically, we are not allowed to protect a 240 circuit with two single-pole breakers, so the use of these breakers would not be allowed in a disconnect.

Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203493 10/03/11 11:23 AM
Joined: Apr 2002
Posts: 7,111
HotLine1 Offline
Member
OK, I have to ask. If you are doing a service upgrade, why would you keep the fuses/fuseblock?

Would not a correctly sized cb in the 'new' panel?

Or, are you talking about maintaining the 'feeder' to the fuse block??



John
Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203495 10/03/11 02:05 PM
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Posts: 152
C
crselectric Offline OP
Member
John the apt, 2nd floor unit has a four screw shell wooden fuse box, #12 knob and tube feeder, and #14 branch circuits, (only two actual circ.s since they used to fuse both hot and return. It was probably originally protected by a two screwshell knife switch back inthe day, with 30amp fuses.....someone took out the steam heat put in new service and replaced knife switches with 8-16 bryant panels, and added two 20 amp 240 feeders for baseboard heating units. and put old in apt. fuse cabinet on 1 20 amp single pole, and left 20 or 25amp fuses in old panel....I'm doing receptacle repair and safety check as the units become available. I've heard customers say that the electrician at the time said they never had to worry about the fuses in the apt box? and this on many occassions at different bldgs. in the SF/ Oakland area.....So I wasa wondering if there ever was a practice of putting entire apt on 1 20amp single pole, now these units probably only had five lights and five plugs, one per room.

Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203496 10/03/11 03:26 PM
Joined: Apr 2002
Posts: 7,111
HotLine1 Offline
Member
OK, now I see the picture. Common practice here, as I was taught by the 'old timers' and to be code compliant:

Splice the neutrals 'thru' to eliminate the screwshell.
Install 'S' fuses and adaptors, sized to the AWG of the branch circuits.

That said, we used to replace the old fuse boxes with either two or four circuit panels, and eliminated the fuses altogether.

Along the same lines, on HVAC replacement jobs, occasionally I see 60 amp fuses in the disco, and the proper CB in the panel to match the MOCP of the new compressor. (Disconnect & feeder not changed)





John
Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203506 10/04/11 02:42 PM
Joined: Sep 2006
Posts: 152
C
crselectric Offline OP
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I was under the impression one couldnt replace the fuses with panels without upping to the new 60amp minimum? or is this a "emergency" replacement work. the owners want to not effect the other units at all costs. Can I as a licensed contractor deem the old feeders insufficient for a 600 sf. apt.? I did add 1 circuit from the basement up the outside with surface wiremold for grounding for surge protector plug strips, but the remaining 8 plugs are non-grounding or gfci ungrounded in kitchen. Thge ownwers of course called me to check it after they repaired all the plaster cracks and repainted.......thanks again. Crs

Re: Protecting old fuse panels with 20amps? [Re: crselectric] #203508 10/04/11 03:30 PM
Joined: Apr 2002
Posts: 7,111
HotLine1 Offline
Member
Here (NJ) we have a 'Rehab' section within the statewide Unifior Construction Code. That allows certain things that do not affect any life safety, to be replaced without conforming to 'current code requirements'.

Keep in mind that this is a New Jersey Code(Law), and may not apply in your area.

That said, replacement of plug fuses that can be 'overfused' with circuit breakers, properly sized is an improvement in safety IMHO.

Also, something that was inspected for code compliance when it was installed (original) is still OK, as long as it is not altered or presenting a dangerous condition.

Again, out of curiousity, where did you arrive with the "60 amp minimum"? From load calculations, or is that a local requirement for apartments?



John
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