Old Murray Panel

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Here's my situation...

Exist. Murray 100A Panel
Class NI Load Center (Model #LC116DS)

Goal: Install (1) 15A Tandem Breaker for (2) Existing 15A Networked Circuits in order to create (1) new space for (1) New 20A Circuit

Murray100AClassNI.jpg

The existing panel is maxed out breaker space wise.

(1) 15A Tandem breaker will be installed per the wiring diagram above in 1 of 4 approved locations at the bottom of the busbars.
A handle tie will be installed since the (2) relevant 15A circuits are currently networked.
This modification will NOT invoke AFCI requirements.
Should it be resolved that AFCI requirements are still invoked, the circuit neutrals will be separated and AFCI protection will be provided at the first opening(s).

The (1) New 20A Circuit will be AFCI Protected per code.

Siemens purchased Murray sometime around 1997. They are currently phasing out the Murray Brand.
My first thought regarding the 15A Tandem breaker, is to find the the Siemens equivalent.

However, in a Letter From Siemens it (1) states that "all Murray Meter Combo Load Centers, EQ Small Circuit Load Centers, and Rock Solid Load Centers manufactured after January 2002 may use Siemens brand circuit breakers... and (2) provides a "cross reference table" for Murray Type Breakers and Siemens Type Breakers.

This particular panel is NOT one of the three listed above, nor was it manufactured after January 2002, evidenced by the Class NI, which existed before Class CTL was introduced around 1965. Therefore, I cannot use the Siemens equivalent in the "cross reference table."

This is further evidenced by the same above letter when it says "For Murray products manufactured prior to January 2002, please refer to the wiring diagram affixed to the inside of the door of the loadcenter for specific breaker types that are approved for that panel."

So Siemens brand equivalent is out and I have to look for the actual Murray Type breaker approved for the panel.

This particular panel lists Murray Types MP and EP as approved. I can't find much info on the EP type, but as far as I can tell, it's an older 3-pole breaker type... or at least 3-poles were all that showed up in my search for the EP type.

In a Letter From UL it states that for panels "manufactured under the UL Files # E-26095 ✅ and E-13207... type MP-T ✅ may be used "whenever the equipment label specifies Types MP ✅ , MP-A, or MP-C circuit breakers."

So this panel allows for Murray Type MP, MP-T, and EP.

This is where I get a little lost...

I know manufacturers make "For Replacement Use Only - Non-CTL" breakers to accommodate older panels pre-CTL, but is this the same thing as a Class NI? It's confusing because it's my understanding that Class NI was basically Class CTL's predecessor and the two accomplish relatively the same thing... and calling something Non-CTL implies an opposing effect.

The only Murray tandem breakers I can find are type MH-T here. It's my understand that this type is not cleared for use in this particular panel.
The only Murray tandem breaker I can find is the Murray MP2020N (N denoted Non-CTL).

It meets the requirements of (1) not being a Siemens brand equivalent, only approved for use in panels manufactured after Jan. 2002... and the requirement of (2) being Non-CTL (assumed to be the same as Class NI) for pre 1968/1965 panels... the problem is, despite the model number alluding to an MP Type, it is actually a MH-T type, which it is my understanding is not approved for this particular panel.

Am I understanding this correctly that I need to find a tandem breaker that is explicitly Type MP, MP-T, or EP as well as being Non-CTL (assuming Class NI and Non-CTL are equivalent)... and NOT MH-T?

And also, regarding the 20A AFCI Breaker, does the breaker type MP-MAT2 (10,000 AIR Catalog #MPA120AFC) shown here on page 13 qualify as Type MP?
 

Bluegrass Boy

Senior Member
Location
Texas
Occupation
Commercial/ Industrial/ Maintenance Electrician
This mentions MP in description, and this site has some odd stuff, but don’t know anything about them. 13F3DA63-1DDE-4BBB-80E6-35E6F952DAB6.jpeg
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
It's looking like justification for complete panel replacement if conditions reported are such that it (the breakers) cannot be replaced, or upgraded by a listed breaker due to the nonexistence of a product that will meet the listing requirements for the panel that you have. I'm sure you would not hesitate to change out a Fed-Pacific or similar panel. Here it's beginning to look like the MFG is making the panel nonservicable, or atleast not expandable, rather than specific safety issues. Or maybe it is thought that the specific panel "is" a safety concern for any expansion and mfg doesn't want to go as far as claiming that, or maybe "oops we forgot that one", just don't know.
An option to consider is you could reach out to Siemens to see what they have for that specific panel to meet your needs (or wants). Then you get it from the "horses mouth" and can provide that as justification to either homeowner or inspector depending on what they (Siemens) reply. https://new.siemens.com/us/en/company/about/contact-us.html
Or you can do what most (non electricians, GC's and the like) around here (anyone can do electrical work) and simply put in whatever breaker kind of fits, almost fits, or fits similar panel. I've found SD HOM in Eaton BR, and visa versa, Westinghouse with SD or GE or Siemens or all of the above. Even found old panels, with no label markings anywhere , it appears the adhesive finaly failed, and the only indication as to identity was the barely visible marking on a main or "what type was the majority of breakers or oldest one in panel" to guess at what it was. And homeowner's response: "Why replace it, it's working", (most seem to consider if the breaker is not tripping - it's working).
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
How about finding a two pole that will replace two standard breakers, set a new sub with 6-8 more spaces than you need?
By "two pole," do you mean Quadplex? Because I would have to land the existing two circuits, plus the feeders for the sub. Either that, or just splice on to the existing two circuits and run them to the new sub panel.

The thing is, there's already a sub panel and it's a bit goofy, lol.

I'm going to suggest a panel upgrade after I prove myself by taking care of this one, new, additional circuit... and explaining to the customer everything I've learned about these types of panels... (i.e. NI versus CTL, the fact that this is such an old Murray panel that you can't utilize the newer Siemens equivalents, and the phasing out of Murray that's currently taking place, etc.)

My main focus is to get this one new circuit taken care of appropriately and learn about the situation I'm currently facing. Suggestion for a new panel will follow what will be a safe and correct installation and hopefully, a happy customer.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
This mentions MP in description, and this site has some odd stuff, but don’t know anything about them.
Thanks for the resource. Appreciate it. I'll check 'em out.
I might not be able to do an AFCI breaker for the 20A circuit and be forced to rely on the first opening exception.

What I'm really looking for is an approved tandem, but MH-T is the only tandems I can find.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
It's looking like justification for complete panel replacement if conditions reported are such that it (the breakers) cannot be replaced, or upgraded by a listed breaker due to the nonexistence of a product that will meet the listing requirements for the panel that you have. I'm sure you would not hesitate to change out a Fed-Pacific or similar panel. Here it's beginning to look like the MFG is making the panel nonservicable, or atleast not expandable, rather than specific safety issues. Or maybe it is thought that the specific panel "is" a safety concern for any expansion and mfg doesn't want to go as far as claiming that, or maybe "oops we forgot that one", just don't know.
An option to consider is you could reach out to Siemens to see what they have for that specific panel to meet your needs (or wants). Then you get it from the "horses mouth" and can provide that as justification to either homeowner or inspector depending on what they (Siemens) reply. https://new.siemens.com/us/en/company/about/contact-us.html
Or you can do what most (non electricians, GC's and the like) around here (anyone can do electrical work) and simply put in whatever breaker kind of fits, almost fits, or fits similar panel. I've found SD HOM in Eaton BR, and visa versa, Westinghouse with SD or GE or Siemens or all of the above. Even found old panels, with no label markings anywhere , it appears the adhesive finaly failed, and the only indication as to identity was the barely visible marking on a main or "what type was the majority of breakers or oldest one in panel" to guess at what it was. And homeowner's response: "Why replace it, it's working", (most seem to consider if the breaker is not tripping - it's working).
I agree that a complete replacement would be warranted. I was just hoping to take of this one smaller project before making such a suggestion. It's also an interesting puzzle to attempt to solve.

Siemens has chosen to phase Murray out entirely, but equivalent Siemens breakers are, according to my understanding, only acceptable in certain types of Murray Panels manufactured after Jan. 2002.

It's my understanding that Post 1968 - Pre Jan. 2002, you have to find the correct Murray's breaker, that is a Class CTL, because it would be a violation of 110.3(B) to put a "Replacement Use Only - Non CTL" breaker in a CTL panel, which became mainstream in 1968.

Pre 1968 / Class NI, you would require a "Replacement Use Only - Non CTL" breaker.

I've already reached out to Siemens and they suggested the MP2020N, but the problem is that this is a Type MH-T, which as far as I can gather, is not approved for use in this panel.
 

kwired

Electron manager
Location
NE Nebraska
Here's my situation...

Exist. Murray 100A Panel
Class NI Load Center (Model #LC116DS)

Goal: Install (1) 15A Tandem Breaker for (2) Existing 15A Networked Circuits in order to create (1) new space for (1) New 20A Circuit

View attachment 2554877

The existing panel is maxed out breaker space wise.

(1) 15A Tandem breaker will be installed per the wiring diagram above in 1 of 4 approved locations at the bottom of the busbars.
A handle tie will be installed since the (2) relevant 15A circuits are currently networked.
This modification will NOT invoke AFCI requirements.
Should it be resolved that AFCI requirements are still invoked, the circuit neutrals will be separated and AFCI protection will be provided at the first opening(s).

The (1) New 20A Circuit will be AFCI Protected per code.

Siemens purchased Murray sometime around 1997. They are currently phasing out the Murray Brand.
My first thought regarding the 15A Tandem breaker, is to find the the Siemens equivalent.

However, in a Letter From Siemens it (1) states that "all Murray Meter Combo Load Centers, EQ Small Circuit Load Centers, and Rock Solid Load Centers manufactured after January 2002 may use Siemens brand circuit breakers... and (2) provides a "cross reference table" for Murray Type Breakers and Siemens Type Breakers.

This particular panel is NOT one of the three listed above, nor was it manufactured after January 2002, evidenced by the Class NI, which existed before Class CTL was introduced around 1965. Therefore, I cannot use the Siemens equivalent in the "cross reference table."

This is further evidenced by the same above letter when it says "For Murray products manufactured prior to January 2002, please refer to the wiring diagram affixed to the inside of the door of the loadcenter for specific breaker types that are approved for that panel."

So Siemens brand equivalent is out and I have to look for the actual Murray Type breaker approved for the panel.

This particular panel lists Murray Types MP and EP as approved. I can't find much info on the EP type, but as far as I can tell, it's an older 3-pole breaker type... or at least 3-poles were all that showed up in my search for the EP type.

In a Letter From UL it states that for panels "manufactured under the UL Files # E-26095 ✅ and E-13207... type MP-T ✅ may be used "whenever the equipment label specifies Types MP ✅ , MP-A, or MP-C circuit breakers."

So this panel allows for Murray Type MP, MP-T, and EP.

This is where I get a little lost...

I know manufacturers make "For Replacement Use Only - Non-CTL" breakers to accommodate older panels pre-CTL, but is this the same thing as a Class NI? It's confusing because it's my understanding that Class NI was basically Class CTL's predecessor and the two accomplish relatively the same thing... and calling something Non-CTL implies an opposing effect.

The only Murray tandem breakers I can find are type MH-T here. It's my understand that this type is not cleared for use in this particular panel.
The only Murray tandem breaker I can find is the Murray MP2020N (N denoted Non-CTL).

It meets the requirements of (1) not being a Siemens brand equivalent, only approved for use in panels manufactured after Jan. 2002... and the requirement of (2) being Non-CTL (assumed to be the same as Class NI) for pre 1968/1965 panels... the problem is, despite the model number alluding to an MP Type, it is actually a MH-T type, which it is my understanding is not approved for this particular panel.

Am I understanding this correctly that I need to find a tandem breaker that is explicitly Type MP, MP-T, or EP as well as being Non-CTL (assuming Class NI and Non-CTL are equivalent)... and NOT MH-T?

And also, regarding the 20A AFCI Breaker, does the breaker type MP-MAT2 (10,000 AIR Catalog #MPA120AFC) shown here on page 13 qualify as Type MP?
What confuses me in the label you posted is if it is old enough to be class NI, which was before CTL, why do they show the bottom spaces as usable with (presumably) CTL tandem breakers? Before CTL they didn't show specific spaces for tandems, they could go on any location.

Or maybe the instruction just means that a class NI breaker will fit this panel?
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Before CTL they didn't show specific spaces for tandems, they could go on any location.
Are you sure? It's my understanding that Class NI did something similar to Class CTL in that it was some sort of physical rejection feature to prevent you from installing the wrong kind of breaker, or a breaker of too high an amperage. In other words, pre-CTL there still existed rejection features that would require certain breakers to go in certain locations... which would explain why this Class NI panel does show specific spaces for tandem breakers.

I think you're confusing the relatively more modern "For Replacement Use Only - Non CTL," which yes, can go anywhere and circumvents rejection features, with what actually existed in Class NI time or an actual Class NI Breaker, which seems to be entirely obsolete.

The thing is, Class NI was very short lived according to my NEC research. It was introduced in 1959 and was gone by 1965 when CTL was introduced to the code. I think it was the very beginning of these rejection features, short lived, and replaced by Class CTL within a few years.
 

norcal

Senior Member
Since the label mentions ITE breakers as being acceptable to use in the panel & Siemens is the successor to ITE, could that be a workaround? It also mentions Bryant BR being acceptable, same thing could apply to Eaton BR (Zinsco II) being a replacement.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
What confuses me in the label you posted is if it is old enough to be class NI, which was before CTL, why do they show the bottom spaces as usable with (presumably) CTL tandem breakers? Before CTL they didn't show specific spaces for tandems....
No.
Tandem breakers have always been limited into where they could be installed. I have seen many pre-CTL wiring diagrams showing where they went.

My guess is that electricians ignored the installation instructions so often the product standard and NEC were eventually changed to the current CTL. Similar to what has happened with neutrals and grounds under a single screw.

NI had to do with installing large amperage breakers. The intent seemed to be that small breakers could be installed anywhere, but larger breakers required some modification to the panel.
 

kwired

Electron manager
Location
NE Nebraska
Are you sure? It's my understanding that Class NI did something similar to Class CTL in that it was some sort of physical rejection feature to prevent you from installing the wrong kind of breaker, or a breaker of too high an amperage. In other words, pre-CTL there still existed rejection features that would require certain breakers to go in certain locations... which would explain why this Class NI panel does show specific spaces for tandem breakers.

I think you're confusing the relatively more modern "For Replacement Use Only - Non CTL," which yes, can go anywhere and circumvents rejection features, with what actually existed in Class NI time or an actual Class NI Breaker, which seems to be entirely obsolete.

The thing is, Class NI was very short lived according to my NEC research. It was introduced in 1959 and was gone by 1965 when CTL was introduced to the code. I think it was the very beginning of these rejection features, short lived, and replaced by Class CTL within a few years.
Was another thread on NI type somewhat recently, particularly involving the QO line of breakers. From recollection that was only for a short time about around 1959 like you said but wasn't around for long.

15 and 20 amp breakers could plug on anywhere in the panel and were basically same thing as still made today. Over 20 amp had a protrusion on the foot of the QO breaker (not sure what rejection feature was on other breaker lines, only seen QO's with this feature myself) I think it could still plug in anywhere in panel but you needed to punch out a segment in the foot rail designed to be punched out (and I believe there was a tool that made it easier to do so) before it would fit the panel.

Think it was intended somewhat as an equivalent to having type S fuseholders and fuses.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
@kwired Yea, I haven't ventured into the QO / Square D side of the issue yet. I'm still getting my head around Class NI v. Class CTL and how it applies to Murray and Siemens (i.e. my particular situation). Interesting stuff though. In my research I stumbled upon something similar to what you're talking about, but glossed over it because it was QO / Square D.

In my previous response, I was merely pointing out that the Non-CTL breakers that circumvent rejection features (i.e. can be placed anywhere) exist to accommodate older panels pre-CTL... but that those older panels/breakers (e.g. Class NI) still had rejection features (i.e. there were still limitations on where and how breakers could be installed... which explains why despite being a non-CTL panel, this particular panel still limits how many and where tandem breakers can be installed.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Just to rope this discussion back in... can anyone confirm that my interpretation of the following is correct?

The Siemens equivalents can only be used on certain Murray panels made after Jan. 2002? ...and I need to find an actual approved type listed on the wiring diagram (i.e. MP, MP-T, EP... or the other approved brands listed in the photo)?? Finally, whatever type is chosen, needs to be non-CTL???

Are there any inherent risks to using these older breakers? Obviously this panel needs to be replaced... but if a safe install can be done prior to making such a recommendation, I would prefer that route.
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Word of caution, some inspectors will fail installation of any refurbished item.
Didn't either '17 or '20 do something about that? I remember reading somewhere that they introduced a definition of "refurbished" but something about it having to be recertified by UL.
 
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