Old Murray Panel

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
I do not know why Siemens doesn't put both Q and MP on the breaker labels
Siemens does provide a cross-reference table that links QP and MP-T, but again, only for panels made after Jan. 2002. And there is additional letter from UL approving of MP-T anywhere MP is listed.
 
Last edited:

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
I would at least try to contact Siemens before replacing a panel. Again, I don't know why they don't make it more plainly obvious on their documentation.
I've spent the last 2 days digging into this issue and several hours on the phone with various Siemens reps.
In the interest of the open-source type sharing of information on this forum, which I value greatly... here is everything I have so far.

I'm still parsing the documents carefully and assembling them via date to see which supersedes which, but nonetheless, here's what I have so far.
Clearly I'm late to this party, lol.
 

Attachments

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Here's a brief summary of the documents attached above....

1993 March - Underwriter’s Laboratories, Inc.
  • Crouse-Hinds Type MH-T Circuit Breakers suitable for use in:
  • Crouse-Hinds herein = Murray if (1) Catalog # or (2) Type are the same
  • Panels Under UL File Numbers #E-26095 and #E-13207
    Murray, Arrow-Hart, Crouse-Hinds, Cooper Industries, Siemens
  • Panels that specify Type MM or Type MH
    Available Fault Current NOT higher than 10,000SA RMS
  • Panels that specify Type MH (15A – 30A Type MH-T only)
    Available Fault Current 10,000A RMS - 22,000A RMS
    MH-T in series with either Type MP-H or Type MD-H
  • Panel that specify Type MH
    Available Fault Current 10,000A RMS - 100,000A RMS
    MH-T in series with 200A Class T Fuses
  • Crouse-Hinds Type MP-GT and Type MP-HGT GFI breakers suitable for use in above panelboards and applications
2002 May - Underwriter’s Laboratories, Inc.
  • Murray Type MP-T Circuit Breakers suitable for use in:
  • Panels Under UL File Numbers #E-26095 and #E-13207
    Murray, Arrow-Hart, Crouse-Hinds, Cooper Industries, Siemens
  • Panels that specify Type MP, Type MP-A, or Type MP-C
2019 September – Siemens
  • Load Centers Manufactured after Jan. 2002
  • (1) Murray Meter Combo Load Center,
  • (2) EQ Sm. Ckt. Load Center,
  • (3) Rock Solid Load Center
  • Utilize Murray to Siemens Cross Reference Table
2019 December – Underwriter’s Laboratories, Inc.
  • Siemens Breakers in Murray Panel
    • Utilize Murray to Siemens Cross Reference Table
    • Similar to September, but with some additions / changes
2020 February - Underwriter’s Laboratories, Inc.
  • Murray Breakers in Siemens Panel
    • Utilize Siemens to Murray Cross Reference Table
    • Inverse of 2019 December Letter = Interchangeability
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
The 1993 letter ALMOST does it for me.... in that it allows for Type MH-T in my UL File #E-26095 Panel... only it goes on to be more specific and identifies panels under said file number that list either Type MM or Type MH, which mine does not.

The Siemens rep. that gave me the 1993 letter implied that because this covers a certain UL File Number, that it extends to my panel under that file number, despite my panel lacking the more in depth specifications that follow in the 1993 letter (i.e. needing to specify Type MM or Type MH).

I wish I could just accept his word on this... but it seems to go against the idea of "layered specifications" in that the letter more broadly addresses my file number, then goes on to state more specific requirements that my panel unfortunately lacks.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
I think I have a solution looking at all this laid out...

The 2002 letter specifies that for my UL File Number #E-26095, anywhere Type MP is listed, Type MP-T is acceptable.. and mine lists Type MP.

While the 2019 September letter (1) applies only to specific panels and (2) imposes a Jan. 2002 cut-off,
the latter 2019 December letter does NOT impose the same cut-off and states that MP-T = QP.

So I think I can use Type QP as long as it's Non-CTL.

The only question that remains is whether or not the 2019 December letter does indeed supersede the 2019 September letter in voiding the previously mentioned 2002 cut-off... and I would be tempted to argue yes.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
If the cross over is approved, they should put both model numbers and/or types on the breaker. I agree.
Siemens might be hesitant to do so for the same reasons I am digging deep into this issue - liability and professionalism.
Or maybe they are trying to sucker you and your client into paying for a panel replacement that's not needed. I would not cast such aspersions were it not for the fact that Murray and Siemens breakers of the last dozen years at least are identical. I defy anyone to tell me which is which with the labels peeled off. So again, whatever reason they have for obfuscating this fact, it can't be very above board.

I'll put it this way: if for reasons of liability and professionalism you're reluctant to put new breakers into a very old panel whose connecting lineage is hard to trace, I might agree with you. But if you were going to be happy putting recently manufactured MP breakers in there, and you're reluctant to put recently manufactured Q breakers, that makes no sense. Because trust me they're the same breaker. (That is, it makes no sense for reasons of liability or professionalism, as opposed to convincing an inexperienced AHJ.)

With that said, thanks very much for posting that documentation. Haven't had time to look through it but hopefully it proves what I'm saying, and will help people with persnickety AHJs.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Or maybe they are trying to sucker you and your client into paying for a panel replacement that's not needed. I would not cast such aspersions were it not for the fact that Murray and Siemens breakers of the last dozen years at least are identical. I defy anyone to tell me which is which with the labels peeled off. So again, whatever reason they have for obfuscating this fact, it can't be very above board.
I definitely wouldn't put it past conventional business ethics to utilize some situation such as this to unnecessarily up-sell additional merch. I would be more in line with your/this position if there wasn't a 60 year time span between this panel and modern Siemens breakers. I think this position definitely has merit relevant to the last decade or two. Beyond that, I think one has to be careful and diligent, that's all.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
I'll put it this way: if for reasons of liability and professionalism you're reluctant to put new breakers into a very old panel whose connecting lineage is hard to trace, I might agree with you. But if you were going to be happy putting recently manufactured MP breakers in there, and you're reluctant to put recently manufactured Q breakers, that makes no sense. Because trust me they're the same breaker. (That is, it makes no sense for reasons of liability or professionalism, as opposed to convincing an inexperienced AHJ.)
Well, it does make sense for liability purposes because type MP is actually listed on the panel and type Q is not. Also, "trust me, they're the same" doesn't hold up in court or on insurance claims as opposed to official documentation on company letterheads.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
With that said, thanks very much for posting that documentation. Haven't had time to look through it but hopefully it proves what I'm saying, and will help people with persnickety AHJs.
You're welcome :) Feel free to let me know if you draw an alternate conclusion from the documents or find additional ones.
 

ramsy

Owner/Operator
Location
LA basin, CA
Occupation
Service Electrician 2017 NEC
..I would not cast such aspersions were it not for the fact that Murray and Siemens breakers of the last dozen years at least are identical.
In link posted in #13 above Eaton describes their CL line, and claims manufacturers are not required to publish all UL tested & listed compatibilities, and only UL reliably publishes that information.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
In link posted in #13 above Eaton describes their CL line, and claims manufacturers are not required to publish all UL tested & listed compatibilities, and only UL reliably publishes that information.
Interesting.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
In case anyone is curious, I just came across an Arrow-Hart 1972 Catalog
It verifies that at one point there was an MP Type tandem and EP Type tandem.

The difference being that the MP Type was "fully magnetic" and the EP Type was "thermal magnetic." (see pg. 6 of catalog)
The existence of both MP Type and EP Type tandems seems to correspond w/ my panel in that it lists both MP and EP as well as has a wiring diagram for tandem positions.

The bridge that I still can't seem to cross is that of Murray's MP // MH.... or Siemens' QP // QT
MH, the more modern MH-T, and the Siemens equivalent QT are returning search results for tandems quite easily.
I can't seem to find many for MP, MP-T, or QP.
 
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