Swapping Breaker Panel Guts

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billyrr

Member
Location
NC
I posted this over at electriciantalk, and only found 1 or 2 guys responding with experience in this topic, so here goes....... I've heard good things about this forum.

Recently I've run across several Siemens/ITE residential main breaker panels with burned spots on the aluminum buss or burned lugs on the main breaker.

The line lugs are separate from the main breaker and those lugs have lugs stabs, into which the main breaker plugs in. The main breaker is similar to four single pole breakers ganged together. Since we're replacing it, the old arrangement wont' matter.

I think these G4040 200a panels are 39" in height. The Siemens G4030 is shorter and the G1224 is much shorter. All have the same lousy main breaker setup and the same lousy al buss. It looks as if the Sq D Homeline HOM 40M, or 40L, or 40V have the right height, depth and width dimensions to cover 39".

Obviously the swapped panel cover, has to cover the 39" height. Most every residential panel is going to be 14 1/4 wide and 4" deep. Is there anything else to look out for? A new panel cover which matches the new guts will obviously line up perfectly, breaker-wise, as long as you have sufficient wireway clearance at the top and bottom of the can. We'd plan to screw the new guts to the back of the old can, screwing through the plastic backing - just as Seimens does it.

I've seen the $400 CH retrofit kit but at that cost, it's a killer. They are not currently UL listed anyway, according to our CH rep.


Yes, I know we can remove the entire old panel and can, but would prefer not to, if that can be avoided.
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
I have used existing cans for commercial panelboards but not for residential. They were designed for this purpose. I have also taken the parts from a new loadcenter and replaced the damaged ones, but they were the same make, model etc. I wouldn't even think of screwing thru the plastic to mount them in another mfgs enclosure. Do it right and replace the whole thing as you know it should be.
 

renosteinke

Senior Member
Location
NE Arkansas
I can understand your desire to make the job as simple as possible, but...

Murphy has a way of messing things up; bolt holes don't line up, etc. Few 'simple' things really are.

Otherwise, you're moving beyond 'electrician' work and becoming a 'panel manufacturer.' It's your call, your responsibility. No one else can say it's "OK," as every situation can be different.
 

220/221

Senior Member
Location
AZ
You will get differing opinions anywhere you ask. It's my opinion that a can is a can.

I did a small one recently with conduit coming in on 3 sides. I could have chopped up the drywall, shortened the conduit and wrestled the new can in place but it made more sense to me to simply replace the bus component.

It was a low end project and I was willing to take the responsibility for the installation.

2011-11-17_09-37-08_67.jpg



2011-11-17_10-52-23_129.jpg


Now, in larger panels, the new covers don't want to fit because the newer panels leave much more room for the feeders. If the new bus component is the same style of breaker and the same amount of spaces, the old cover will fit.

GEnerally, on a flush mounted panel or one with a bunch of conduits that will be difficult to refit, I will continue to use the existing can whenever it makes sense.

I did a larger panel recently and the panel cover was missing. It easily took an extra 3 hours to wrestle the old one out and the new one in.
 

kwired

Electron manager
Location
NE Nebraska
The panelboard is the interior portion.

The enclosure is a cabinet.

Small panels typically are sold as complete panelboard, cabinet and cover preassembled except possibly the cover.

Commercial and industrial type panels are typically ordered as separate panelboard, separate cabinet, separate cover, as well as other accessories being ordered separately like main breaker kits, feed through lug kits, etc.

It would not be a NEC violation to order the panelboard an put it in the cabinet of your choice.

It will likely cost less to use the cabinet the panelboard manufacturer has designed to work easily with the panelboard and other components, and certainly everything should fit together without field fabrication, as long as correct components were ordered.


I think you need to use your own judgement on whether or not it is good to just change the guts.

20 circuit or less panel doesn't necessarily take that much to change sometimes.

42 circuit panel with NM randomly terminated is usually a mess whether you replace the whole thing or not.

You could possibly also use the old panel as a junction box and extend circuits to the new panelboard right next to it or something like that.

Stay away from panels that have plug on main breaker, especially over 125 amp with aluminum bus.
 

Article 90.1

Senior Member
The new Siemens main breakers tend to be off centered and the older ones tend to be centered. If you do a 20/20 or a 20/40 interior swap don't center the main breaker, but center the guts, simple enough. You will also have to snap off the plastic tabs on the new guts that are designed to slide into the new can and not the old. You will also be using the new panel cover because of the offset main opening, so start the whole process by measuring off of the panel cover holes. The MBJ screw of the new guts won't line up with any threaded hole so get your 10/32 tap out (may be 10/24, but I don't think so) and re-use the existing MBJ method (the copper strap).
 

iwire

Moderator
Staff member
Location
Massachusetts
You will get differing opinions anywhere you ask. It's my opinion that a can is a can.
I agree with you, in my opinion a cabinet (Article 312) is a cabinet and electricity does not know the difference between a CH cabinet and a Square D cabinet. I have in the past just swapped the guts and not the can.

But our own opinions mean absolutely nothing.



Recently I've run across several Siemens/ITE residential main breaker panels with burned spots on the aluminum buss or burned lugs on the main breaker.

The line lugs are separate from the main breaker and those lugs have lugs stabs, into which the main breaker plugs in. The main breaker is similar to four single pole breakers ganged together. Since we're replacing it, the old arrangement wont' matter.

I think these G4040 200a panels are 39" in height. The Siemens G4030 is shorter and the G1224 is much shorter. All have the same lousy main breaker setup and the same lousy al buss. It looks as if the Sq D Homeline HOM 40M, or 40L, or 40V have the right height, depth and width dimensions to cover 39".

Obviously the swapped panel cover, has to cover the 39" height. Most every residential panel is going to be 14 1/4 wide and 4" deep. Is there anything else to look out for? A new panel cover which matches the new guts will obviously line up perfectly, breaker-wise, as long as you have sufficient wireway clearance at the top and bottom of the can. We'd plan to screw the new guts to the back of the old can, screwing through the plastic backing - just as Seimens does it.

I've seen the $400 CH retrofit kit but at that cost, it's a killer. They are not currently UL listed anyway, according to our CH rep.


Yes, I know we can remove the entire old panel and can, but would prefer not to, if that can be avoided.[/FONT][/COLOR]
As pointed out above the opinions here do not really matter, it will be the opinion of the inspector that will matter.

Code wise at the minimum the inspector could likely fail you on 110.3(B).


110.3 Examination, Identification, Installation, and Use
of Equipment.

(B) Installation and Use. Listed or labeled equipment
shall be installed and used in accordance with any instructions
included in the listing or labeling.

The new panelboard (Article 408) will likely be listed and will likely instruct you to use the cabinet that came with it.

Now UL says it is the AHJs responsibility to determine if the use of the product is different enough to require a fail or a field evaluation by UL. What will your inspector say? No one here knows, in my own opinion as an electrician if you did a nice job and it looks good they should pass it.:thumbsup:

However on the other hand if I was an inspector I would need to think about covering my own rear and I was to let enough things go eventually it will likely bite me.


Beyond 110.3(B) there could also be wire bending space issues (408.3(G)) with a new panelboard in an old cabinet.


If I was asked to price this job I would price it using listed retrofit panels and price changing the whole thing and let the customer decide. If I got underbid by someone just doing a unlisted swap I would just have to live with that.

At the very least talk with your inspector before moving ahead. Doing it over really takes the money out of the job.
 
Last edited:

kwired

Electron manager
Location
NE Nebraska
The new Siemens main breakers tend to be off centered and the older ones tend to be centered. If you do a 20/20 or a 20/40 interior swap don't center the main breaker, but center the guts, simple enough. You will also have to snap off the plastic tabs on the new guts that are designed to slide into the new can and not the old. You will also be using the new panel cover because of the offset main opening, so start the whole process by measuring off of the panel cover holes. The MBJ screw of the new guts won't line up with any threaded hole so get your 10/32 tap out (may be 10/24, but I don't think so) and re-use the existing MBJ method (the copper strap).
The problem with drilling a new MBJ hole is the thickness of the cabinet may not be enough to comply with 250.8. The factory made holes for this often where they made the thickness around the hole thicker than the rest of the cabinet.
 

billyrr

Member
Location
NC
I would love to see what 'Kwired' is referring to! I do not doubt him at all, but man it would take some extreme effort for a mfg, to produce panel cans with area containing different gauge metal.

I'm been in a metal stamping plant where flat sheets are turned into panel cans in one stroke on a punch press. Typically forming knockouts takes a second stroke.

To create an area of greater thickness I would guess that a mfg. would have to weld in another plate to achieve an area of greater thickness, and I'm guessing that few would be willing to go to that trouble.

While I am confident Kwired is right, I'd bet that 9 out of 10 panels are of the same gauge throughout!

I completely agree that you will need to re-tap the cabinet for the bonding screw and that should take about a minute flat! :)
 

kwired

Electron manager
Location
NE Nebraska
I would love to see what 'Kwired' is referring to! I do not doubt him at all, but man it would take some extreme effort for a mfg, to produce panel cans with area containing different gauge metal.

I'm been in a metal stamping plant where flat sheets are turned into panel cans in one stroke on a punch press. Typically forming knockouts takes a second stroke.

To create an area of greater thickness I would guess that a mfg. would have to weld in another plate to achieve an area of greater thickness, and I'm guessing that few would be willing to go to that trouble.

While I am confident Kwired is right, I'd bet that 9 out of 10 panels are of the same gauge throughout!

I completely agree that you will need to re-tap the cabinet for the bonding screw and that should take about a minute flat! :)
Why don't you take a look at most of the cans that are made today. I am mostly familiar with Square D but most of them are like what I described as far as I know. They don't just drill or punch the hole for the bonding screw but somehow extrude the metal from that hole and have more thickness right where that hole is. Even holes for mounting screws for interior components are often like this.
 

iwire

Moderator
Staff member
Location
Massachusetts
In most cases they just punch the hole for the screw and the displaced material is rolled down into the hole making a thicker area for the threads.
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
In my opinion I think iwire's reference to 110.3 is the main issue at hand. Panelboards and load centers are UL listed TOGETHER, even if sold separately. Yes you can exchange can sizes within a mfrs product line on some units, but the size changes are still tested and listed by the mfr in any possible combination that you can perform in the field. Beside wire bending space, there is also a temperature rise test. No way is a mfr of an interior going to bother testing the temperature rise of it in someone else's box.

I have in the past, as a UL shop, used interiors only (with trim) as a quasi-distribution bus system inside of a control panel and had the UL inspector buy off on it, but that was because the box I was using was 10X the size of the original box. You might, in a similar situation, be able to persuade an AHJ of suitability, but in general once you substantially change something you have violated that listing and at that point it becomes a judgement call by the AHJ. You have to really want it to take the risk of having to yank it and redo anyway. In my mind, not worth it.
 

Fulthrotl

~~Please excuse the mess. Sig under construction~~
In my opinion I think iwire's reference to 110.3 is the main issue at hand. Panelboards and load centers are UL listed TOGETHER, even if sold separately. Yes you can exchange can sizes within a mfrs product line on some units, but the size changes are still tested and listed by the mfr in any possible combination that you can perform in the field. Beside wire bending space, there is also a temperature rise test. No way is a mfr of an interior going to bother testing the temperature rise of it in someone else's box.

I have in the past, as a UL shop, used interiors only (with trim) as a quasi-distribution bus system inside of a control panel and had the UL inspector buy off on it, but that was because the box I was using was 10X the size of the original box. You might, in a similar situation, be able to persuade an AHJ of suitability, but in general once you substantially change something you have violated that listing and at that point it becomes a judgement call by the AHJ. You have to really want it to take the risk of having to yank it and redo anyway. In my mind, not worth it.
i'll echo with the majority on this one.... before i did it, i'd show up at the counter and see if i could talk to the exact inspector who would be signing my ticket.
i'd talk to him, explaining what i wanted to do, and why, and make sure he was ok with it.

there's a "no splices in panelboards" thing with most inspectors, for instance.
technically, the interior is the panelboard, and the can it's mounted in is not
part of that panelboard, so splices are permitted, so i was told by one inspector
locally here.

and another inspector with the same city, will not buy a wire nut inside the enclosure.

so, if you call for inspection on 1st and 3rd fridays, you will not get the approval,
as the "no wirenut" guy is doing the other guys inspections that day.

in addition to his own, so he's crabby to boot.

me, i just rip out the box, put in the listed enclosure, put a 6x6x12" 3r gutter on the
end of the panel with the branch circuits, and pigtail everything into the panel in #10
stranded, thru a 2" chase nipple with a ground bushing. then i cover the whole thing
with a stainless steel flange using sealant to weatherproof the flange to the wall.

no splices in the panel, everything dereated thru the nipple, etc.

never been turned down... most inspectors are pretty good with it.
 

iwire

Moderator
Staff member
Location
Massachusetts
there's a "no splices in panelboards" thing with most inspectors, for instance.
technically, the interior is the panelboard, and the can it's mounted in is not
part of that panelboard, so splices are permitted, so i was told by one inspector
locally here.
312.8 Switch and Overcurrent Device Enclosures with
Splices, Taps, and Feed-Through Conductors.
The wiring
space of enclosures for switches or overcurrent devices
shall be permitted for conductors feeding through, spliced,
or tapping off to other enclosures, switches, or overcurrent
devices where all of the following conditions are met:

(1) The total of all conductors installed at any cross section
of the wiring space does not exceed 40 percent of the
cross-sectional area of that space.

(2) The total area of all conductors, splices, and taps installed
at any cross section of the wiring space does not
exceed 75 percent of the cross-sectional area of that
space.

(3) A warning label is applied to the enclosure that identifies
the closest disconnecting means for any feedthrough
conductors.
 

kwired

Electron manager
Location
NE Nebraska
i'll echo with the majority on this one.... before i did it, i'd show up at the counter and see if i could talk to the exact inspector who would be signing my ticket.
i'd talk to him, explaining what i wanted to do, and why, and make sure he was ok with it.

there's a "no splices in panelboards" thing with most inspectors, for instance.
technically, the interior is the panelboard, and the can it's mounted in is not
part of that panelboard, so splices are permitted, so i was told by one inspector
locally here.

and another inspector with the same city, will not buy a wire nut inside the enclosure.

so, if you call for inspection on 1st and 3rd fridays, you will not get the approval,
as the "no wirenut" guy is doing the other guys inspections that day.

in addition to his own, so he's crabby to boot.

me, i just rip out the box, put in the listed enclosure, put a 6x6x12" 3r gutter on the
end of the panel with the branch circuits, and pigtail everything into the panel in #10
stranded, thru a 2" chase nipple with a ground bushing. then i cover the whole thing
with a stainless steel flange using sealant to weatherproof the flange to the wall.

no splices in the panel, everything dereated thru the nipple, etc.

never been turned down... most inspectors are pretty good with it.
Why should they turn it down? Nothing wrong with doing more than code requires as a minimum.

If the nipples are shorter than 24" you did not need to derate the conductors either.

You can put a lot of wire nuts in a typical dwelling panel and not overfill it according to 312.8 permissions. Splices in 12 and 14 AWG conductors does not take a lot of room as long as you don't try to put all of them in the same place.
 

Cow

Senior Member
Location
Eastern Oregon
there's a "no splices in panelboards" thing with most inspectors, for instance.
technically, the interior is the panelboard, and the can it's mounted in is not
part of that panelboard, so splices are permitted, so i was told by one inspector
locally here.

and another inspector with the same city, will not buy a wire nut inside the enclosure.
I usually can't do a service change without a few wirenuts to extend some circuits. I can't imagine having to add a j-box just to splice in. What a total lack of common sense as well as utter disregard for the code on the inspectors part.
 
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