Confused by this Old Load Center

[TimG61]

I am helping my mother-in-law with a few issues in her home, and when I opened up the electrical panel to shut off a circuit for a light fixture replacement, it was a mess.

Three things confused me, and I wanted to bounce my questions off the folks who do more electrical work than me.

It's a surface mount single phase 100A Murray load center (model LC116DS). 16 spaces, 20 circuits. I'm attaching a photo of the panel info sheet as Image 1.

These are the things I did not understand:

1) Slot 1 contains a tandem 15A breaker. That seems like a problem since the panel electrical diagram shows that as a single breaker position.

2) When I read the label on the tandem breaker in slot 1, it claims to be a 2-pole breaker? The breaker is a Thomas & Betts type TBBR and it lists "2 pole YF-6738" on the label. I attached a photo as Image 2. Both sides of this breaker feed separate 120V lighting and convenience outlet circuits in second floor bedrooms. If this is really a 2-pole breaker, I expected it to feed two hot legs to a 240V appliance or HVAC unit.

3) Slots 11 and 13/15 contain tandem 20A Bryant BRD breakers. The four attached wires (two red, two black) feed a single 240V in-wall A/C unit in her living room. Here again, slot 11 does not appear to be designed for a tandem. And I don't understand the use of two tandems to separately switch four hot wires instead of a standard 2-pole breaker and two hot wires. I am attaching a photo as Image 3.

Also, there are four slots in the panel (13/15, 17/19, 14/16 and 18/20)that are designed for tandem breakers, so the three tandems could have been accommodated in designated slots. Why would someone have put two of the tandems into slots that we not designed for them?

Is splitting a "2 pole" breaker and using the two hots separately a common thing (like they appeared to have done in Slot 1)?

What's up with the dual tandem breakers in slots 11 and 13/15? Shouldn't that just be a standard 2-pole breaker rated for the A/C unit?

I did successfully change the ceiling light fixture that I went there to do. Those of you with more electrical experience than me may say this is all normal. If so, great. If not, I want to know what I'm getting mom into when I call in an electrician.

Many thanks to anyone who can educate me on this. I appreciate your time and sharing of knowledge!

Tim

 

[Jim greengo]

Pull em off and see if somebody modified them to fit.
Either way I'm guessing they aren't listed for that panel,so replace them with Murray breakers.

 

[sparky 1971]

Tandem breakers can be fit into places they aren't supposed to go. It's really not that difficult, especially if they are not CTL. As far as the 240 for the AC, you have two breakers on two phases. On wire to each breaker will make 240. Is it right? Nope. Is it done? Yep. It should have a quad breaker in the proper part of the panel. Murray is no more, but I think Siemens breakers are listed to work in Murrays.

Bryant breakers fit, but aren't listed for use in a Murray panel. Those have become Eaton BR.

 

[sparky 1971]

Pull em off and see if somebody modified them to fit.
Either way I'm guessing they aren't listed for that panel,so replace them with Murray breakers.

Those old Bryant's would fit about anything, anywhere. Just like the Eaton BR's of today as well as the Siemens non CTL. It's the Siemens CTL breakers that need to be modified to fit. (At least, that's what I've heard.)

 

[TimG61]

Thank you Jim and Sparky. I'm home now, but I'll head back there in a day or two and pop the breakers off to see if they were modified. It's probably old enough that there wasn't a rejection tab in the way. You think a standard Siemens QP (ex. QP120) would work?

 

[sparky 1971]

Thank you Jim and Sparky. I'm home now, but I'll head back there in a day or two and pop the breakers off to see if they were modified. It's probably old enough that there wasn't a rejection tab in the way. You think a standard Siemens QP (ex. QP120) would work?

Yes

 

[wyliesdiesels]

neither of those breakers are listed for use in that panel and tandems should only go in the bottom 4 spaces.

 

[Jim greengo]

Thank you Jim and Sparky. I'm home now, but I'll head back there in a day or two and pop the breakers off to see if they were modified. It's probably old enough that there wasn't a rejection tab in the way. You think a standard Siemens QP (ex. QP120) would work?

I know you could still get Murray breakers in omaha up till a couple years ago anyway,last time I got some a supply house anyway.
I think it was midlands electric supply that was a dealer for them.

 

[Norcal]

Siemens is the listed replacement for Murray, & the label also listed ITE, which Siemens is the successor company. So can't go wrong with Siemens.

 

[reader2580]

Siemens discontinued Murray breakers in late 2019. Any Murray panel made in 2002 or later can use Siemens breakers and still be UL listed. I don't know what guidance Siemens has for panels as old as the on in the picture.

 

[Norcal]

Siemens discontinued Murray breakers in late 2019. Any Murray panel made in 2002 or later can use Siemens breakers and still be UL listed. I don't know what guidance Siemens has for panels as old as the on in the picture.

May be able to use Eaton CL. Note: They are not the same as BR.

 

[sparky 1971]

The part of the label that says ITE is enough to convince me that Siemens is ok. Actually, it takes less than that for me to be willing to use a Siemens breaker. I carry QO, Homeline, and Siemens with a few others randomly mixed in on my van. If it fits, it ships.

 

[BreeStephany]

I recently helped a friend that had an OLD 200A Murray panel that had a 20A single pole T&B breaker and a 20A single pole Bryant breaker and both, while still feeding correct voltage on the load side, we're absolutely COOKED at the bussing clamps and on the verge of likely starting a fire.

Several of the original Murray breakers were also on the verge of failure and while not showing signs of arc or overheating, were internally vibrating under load.

I opted to replace ALL of the breakers with Siemens and abandoned / blanked and labeled "space not for use" due to slight discoloring of the bus tabs where the T&B and Bryant breakers were previously installed.

The Siemens breakers were a direct fit to the Murray breakers and appeared identical in design. I did a fair share of research and came up with the conclusion that the Siemens breakers were a suitable replacement.

I made my friend aware of the situation and based on the fact that the discolored bus was furthest away from the main disconnect, that the discoloring was isolated only to the tabs and did not extend into the main bussing and by the fact that all of the other bussing looked practically new, I opted for breaker replacement vs. panel swap.

Had there been damage to the main bus or had the panel been a split phase panel, I would have informed them that this would be a much more costly job and would have recommended a panel swap.

Just my two cents!

 

[Norcal]

T&B breakers were UL classified for competitive panels, but have not been marketed in many years.

 

[The Cobbler]

another case where original poster has not logged in since posting... 2 months ago

 

[TimG61]

Sorry Cobbler. I was reading the alerts as they came via email. This was very helpful.

Based on the comments and after popping off the breakers as suggested to check the condition of everything, I bought a new Siemens 100A load center with more slots, got rid of the tandems and gave Mom some room for expansion.

That was a pretty simple swap. Wish I could have got her onto to some GFI breakers instead of using the outlets but with that old wiring scheme it was not in the cards.

Thanks to all, especially Jim, Sparky, NorCal and
Bree. Really appreciate the info you shared.

The mother in law thanks you too!