Let's talk about this very old panel.

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fastline

Senior Member
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midwest usa
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Engineer
Trying to do some remodeling of this shop space and I'd like to be able to run this panel. Obviously every single thing needs evaluated but I am wondering about a complete panel work up plus new breakers? Or does this girl need scrapped?? I really don't want to have to pull the box. I'm sure the Copper in it is good to go.

There was some power moved around before I got in and appears they literally ran a dedicated EMT overhead just to avoid having to deal with this panel...lol This panel is fed under slab, so I like it. But has like 10 EMT takeoffs.
 

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If it ain't broke, don’t fix it.

If it's working well now I would leave it alone. Just make sure you can get breakers for it.
 
That looks like an "NQB" panel board it is roughly 70years old. It depends on your panel catalog number of the interior assembly. The number on the front is the factory order number.
Square D, and other manufacturers, can easily build an interior and custom cover that allows you to keep your box. They just need accurate dimensions; inside, outside, and the turned in flanges. They even have box extensions if need for extra depth.
 
I am going to have to close this thread. Unless I am mistaken, and please PM me if I am, this is not a design project for which you are the assigned engineer. It looks more like a project at your own home. We can't help you with DIY installation work.
 
I received a PM from fastline, clarifying that this is a work-related project, not a DIY situation. I reopened the thread. I apologize for the delay and inconvenience.
 
Welp, SD has not been much help but with some work, I think I have discovered this to be an ML panel board. SD's website says they have adapters for different breakers but recommends replacement and enclosures have changed.

Sounds like the MLs were done in the 60s, which is consistent with building age, but could have fooled me. It looks like it's from the 30s....

Hmm.... I really don't want to open a can of worms pushing for a total replacement. I'll have to ponder. Thoughts?
 
Curious if you have dimensions, and curious if there might be a way to change just the guts. Even if a custom cover had to be fabricated
 
I guess I was hoping this model was familiar to you guys, thus probably serviceable. I have not yet measured anything. I think the first step might be to compare these old breakers to modern pieces to see if ideas come to mind. Would not be the first time we've had to do minor 'mods' to make things work right.

What was MORE of a shocker is I was back in the space today on other business and decided to confirm that panel was dead. Dude, it is hot as hell! I want that thing tagged out yesterday because I'm looking at the guts of several 120V duplexes hanging out, conduits chopped off, etc. Every single breaker is on. Wild!

I am now thinking the overhead conduit got tossed in because that panel appears loaded up and someone didn't even want to touch it. Probably just said "too old, must come out".... I'm betting half of those 120V breakers are not doing anything.
 
fastline said:
Welp, SD has not been much help but with some work, I think I have discovered this to be an ML panel board. SD's website says they have adapters for different breakers but recommends replacement and enclosures have changed.

Sounds like the MLs were done in the 60s, which is consistent with building age, but could have fooled me. It looks like it's from the 30s....

Hmm.... I really don't want to open a can of worms pushing for a total replacement. I'll have to ponder. Thoughts?
Click to expand...
ML panel boards were the industrial panel typically used in industrial power applications. ML panels were used for several decades before the introduction of the I-Line family. The breakers were type ML-1, ML-2, and Ml-3 although they were usually sold based on their catalog numbers, which had the format 99xxxx. Square D offered many panel styles where the breaker look very similar

Regardless, all of these panels have been obsolete for more than 50 years. I think I sold my last ML bus adapter back in the late 80's. These allowed the then new style FA/KA/LA breakers to be installed.

Replace the panel guts and front. If your supply house can't help you, find a new supply house. Yeah, it might need to be ordered from the factory, but every major manufacturer offers something.
 
jim dungar said:
ML panel boards were the industrial panel typically used in industrial power applications. ML panels were used for several decades before the introduction of the I-Line family. The breakers were type ML-1, ML-2, and Ml-3 although they were usually sold based on their catalog numbers, which had the format 99xxxx. Square D offered many panel styles where the breaker look very similar

Regardless, all of these panels have been obsolete for more than 50 years. I think I sold my last ML bus adapter back in the late 80's. These allowed the then new style FA/KA/LA breakers to be installed.

Replace the panel guts and front. If your supply house can't help you, find a new supply house. Yeah, it might need to be ordered from the factory, but every major manufacturer offers something.
Click to expand...
Was there anything inherently dangerous or problematic with the ML line? As part of the update, I need to assess certain risk factors. Hopefully nothing like the old FP gear.
 
fastline said:
Was there anything inherently dangerous or problematic with the ML line? As part of the update, I need to assess certain risk factors. Hopefully nothing like the old FP gear.
Click to expand...
FPE's problem is with Stab Loc loadcenters, I have not heard of any issues with other FPE products.
 
fastline said:
Was there anything inherently dangerous or problematic with the ML line? As part of the update, I need to assess certain risk factors. Hopefully nothing like the old FP gear.
Click to expand...
No. You are just looking at age of the installation and probable lack of routine maintenance.
In general molded case breakers, including non-residential FPE, have not had histories of being problematic (under the right conditions every breaker can be used for "welding').
 
I have replaced the innards many times, and used the new cover by drilling new holes in the edge of the old enclosure.
 
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