Replacing Murray 100 amp Main Breaker

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  #1  
Old 11-10-12, 09:13 AM
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Replacing Murray 100 amp Main Breaker

After Hurricane Sandy, the POCO restored our electricity and damaged our breaker/panel. I checked with a multimeter and phase to phase reads 220V, so I know power is restored, however the house is still without electricity.

I am no electrician, but my guess is that the main breaker is bad. When the main breaker is "on" and I put the slightest pressure on the switch, it "jumps" to the off position. It feels (to me at least) much to easy to turn off. This seems like a problem in the breaker, but I'm not sure. Any thoughts on this?

The panel is a Murray LC120DS/DF and the main breaker is a Murray 100-amp 2 pole style MPX. I would like to replace the main breaker, but everywhere I look I only find "MP" style not "MPX". The instructions on the panel state to use an 'MP" breaker, but the breaker definitely says "MPX". Here is a guy with the same exact Panel and breaker:

http://www.doityourself.com/forum/el...t-breaker.html

The difference, from what I can see, is that the MPX has the lugs on the top, whereas the MP has the lugs on the bottom.

Does anyone have any experience with this panel? If I get the POCO to shut off the power, is it fairly simple to replace the main breaker? Does it just pull out and push in like a standard breaker?
I'm looking at this one from HomeDepot: 100 Amp 2 in. Double-Pole Circuit Breaker-MP2100P at The Home Depot

Thanks to all in advance.
 
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  #2  
Old 11-10-12, 12:32 PM
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Welcome to the forums!

The breaker you linked to is a plug-in breaker. I don't see any lugs on it.

Some pictures of your panel, including one far enough away to see the full installation, one of the label inside the door, and one of the interior with the deadfront removed, will help us focus our answers on your question. See How To Include Pictures.
 
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Old 11-10-12, 05:40 PM
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The panel is a Murray LC120DS/DF
How old is the Murray panel? Is it marked AH Murray or Arrow-Hart Murray? If it has either of those markings, it's the old Murray from 30 plus years ago and that's really old as aluminum bus panels go. If the panel label says Siemens at the bottom in smaller print it would be the newer Murray which is entirely different and now a Siemens clone. I suspect you have the older Murray aluminum bus panel and I don't know the exact difference between an "MP" and an "MPX" breaker, but suspect it could just be a higher interrupting capacity or it could even be a bolt-in style. In those days Murray was near the bottom in quality, but was used frequently because of price. I think I'd bite the bullet and replace the panel. Or.....if you want immediate results, try buying the "MP" 100 amp breaker you found and see if it will physically fit, you might get lucky. By the way, you can buy a new 30 circuit 100 amp copper bus Cutler-Hammer panel at Home depot with 4 or 5 breakers included for $78. The breaker you found costs half that much.
 
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Old 11-10-12, 10:15 PM
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Here are some pictures

OK. I finally took some pictures of the panel. Attached to the main you will see the two mains from the POCO, plus two black (in front) which feed a smaller panel.

 
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Old 11-10-12, 10:20 PM
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The front of the panel is marked "Murray" only.
 
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Old 11-10-12, 10:24 PM
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Nashkat1, so if it's a Plug-in breaker, will I still be able to connect two cables to each side as I currently have it?
 
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Old 11-10-12, 10:27 PM
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It is clear that the panel manufacture date was prior to 1963 since the address does not use the five digit ZIP code that was mandated in that year.


Nashkat1, so if it's a Plug-in breaker, will I still be able to connect two cables to each side as I currently have it?
That is a definite code violation.
 
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Old 11-10-12, 10:47 PM
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That is a definite code violation.
It would seem that way even to a layman such as myself. But since it passed inspection when I bought the house a few years ago, I figured it was OK.
 
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Old 11-10-12, 11:38 PM
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That Murray breaker you linked to should work fine. Your panel use Murray and Bryant breakers. Bryant breakers were known for their blue 15 amp handles and red 20 amp handles. Inspectors don't normally open panel covers therefore he probably didn't see that. I won't go into what I think of most home inspectors.

Those double wires in the main breaker are more than a code violation....they are dangerous.
 
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Old 11-11-12, 07:50 AM
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Yes, that is a very old Murray that pre-dates the Arrow-Hart name. Good catch Furd on no zip code. I also notice the address is Brooklyn 16, N.Y. I had forgotten about those old postal zone designations and the old way of abbreviating a state. If the MP100 fits, I still wouldn't use it and would opt for panel replacement. If it fits and the panel has the proper stabs for breaker installation, the new breaker handle would be in the "Down" position when "On" and "UP" position when "Off". The second set of wires double lugged in the main breaker is a definite violation and likely wouldn't fit in any new breaker anyway (for good reason). The second set of wires should go to their own 2 pole circuit breaker.
 
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Old 11-11-12, 11:39 AM
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Nashkat1, so if it's a Plug-in breaker, will I still be able to connect two cables to each side as I currently have it?
Just so you have my answer, no. Not only can you not keep it that way, it shouldn't be that way now, and never should have been. To paraphrase what Furd and PJmax have said, having that pair of wires tapped in on the POCO, or unprotected, side of your main overcurrent protection device is a clear code violation because it is dangerous. It was illegal and dangerous when it was installed, and it still is.

It doesn't matter what those wires are tied into on the other end. Until they get there, they are carrying the full potential supplied by the POCO. They are protected only by the closest upstream protection device in the POCO system, which, if you are lucky, may be not far outside the boundaries of your property.

since it passed inspection when I bought the house a few years ago, I figured it was OK.
This is a common misconception. Your house passed inspection. Your electrical panel didn't. It wasn't inspected. Home inspectors don't open and inspect electrical panels, as a matter of professional practice. They're not qualified to; only a licensed and experienced master electrician is qualified to do that. If a home inspector opened a panel and offered a professional opinion on it, that inspector would be certifying that everything about that panel met the applicable code and followed best standard practice. Home inspectors don't carry enough insurance to cover the consequences of being wrong about that. Master electricians do, in most states.

I'll just add that, in addition to the second panel and its unprotected feeders, which is the howler that caught everyone's attention, you have two pairs of tandem breakers in the section of the panel that is not designed to accept tandems - positions 1 and 3 - and a 2-pole 240V breaker in the section that is not designed for those - positions "14-16" and "18-20." Don't get me started on all the things that are not up to code about your current setup.

Here are your best next steps on this project:
  • Cover and close the panel, and restore the power (I'm guessing that you've already done this one;
  • Do the residential load calculation to determine whether you need to upgrade to a 200A service (probably not, but you won't know until you do that calculation. Remember to include any loads you might want to add in the future, and bear in mind that the additional cost may be only pennies.);
  • Ask your neighbors for referrals for qualified and licensed electrical contractors with whom they've had good experiences;
  • Buy and read Wiring Simplified, which is, quite simply, both the best and the least expensive reference on how residential services are wired, and why each procedure is done the way it is.
Good luck, and enjoy the ride!
 
  #12  
Old 11-12-12, 11:29 AM
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Wow! Thanks guys. I've really learned a lot so far.

The 2-pole breaker on 14-16 and 18-20 feeds an a/c unit. My guess, by looking at the diagram, is that it should be moved to positions 2-4 or 1-3. Correct?

I'm having a qualified licensed electrician come over to change the main breaker and bring things up to code.

Thanks again for everyone's help.
 
  #13  
Old 11-12-12, 12:43 PM
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The 2-pole breaker on 14-16 and 18-20 feeds an a/c unit. My guess, by looking at the diagram, is that it should be moved to positions 2-4 or 1-3. Correct?
I would move the 2 pole breaker to positions 1-3 to get the tandem breakers out of the area where they don't belong. Have you found a new main breaker yet?
 
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Old 11-12-12, 08:11 PM
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The 2-pole breaker on 14-16 and 18-20 feeds an a/c unit. My guess, by looking at the diagram, is that it should be moved to positions 2-4 or 1-3. Correct?
Yes, either one. Then you will need to free up the other 2-pole position for a breaker to protect the wires feeding the second panel. You can do that by replacing the two full-size 20A breakers in positions 4 and "6-8" with a pair of tandem breakers in position "6-8."

Replacing the existing panels might be the fastest and least expensive way to bring everything up to code.
 
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Old 11-12-12, 08:17 PM
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For the number of issues with your panel and the cost of a new reliable panel, I would have a new panel installed. You would also pick up space for more circuits.
 
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Old 11-13-12, 10:46 AM
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For the number of issues with your panel and the cost of a new reliable panel, I would have a new panel installed. You would also pick up space for more circuits.
There was something I meant to say in my last post, but forgot: You haven't showed us your second panel, so we don't know how many circuits it supplies. However, unless that panel is significantly larger than the one we've seen, a new standard-size residential panel should have enough spaces to supply all of the circuits now being supplied from both of your existing panels. IOW, you should be able to replace both of your existing panels with one new panel.
 
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