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This is a follow up to my previous question.

Thanks to the advice there, I am planning to replace my existing double-pole breaker with a quadruplex breaker.

How do I determine that my panel can take the quadruplex breaker? My panel is Murray LC3040L and I'm looking at this Murray quadruplex breaker. Are those two compatible?

  • In my limited experience, unless you can find a manufacturer's document, you may just have to try it and see if it fits, returning it if it doesn't. – keshlam Jan 31 '16 at 22:50
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    @keshlam just FYI there are many cases where a breaker will fit and (probably) work fine but not be allowed by code because it isn't certified by the panel manufacturer. – DoxyLover Jan 31 '16 at 23:09
  • Good point, @doxylover. Some day I will need to replace my panel because finding legitimate breakers is getting difficult... – keshlam Jan 31 '16 at 23:57
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The breaker you picked should work fine. To determine it for sure, read the fine print on the label on the interior of the door panel. It should list a series of 10-20 types of breakers that are compatible with your panel. They are often 2 to 4 letter codes. The actual breaker models will be that code, and then a number.

Duplex, Triplex, and Quadruplex breakers often have an incompatibility tab on them to prevent you from using them in some slots of your panel. This is called 'circuit limiting'. Your panel has 30 lots, and is "rated" for a maximum of 40 circuits. Thusly, only the bottom ten slots (five rows ) "permit" you to install a duplex, triplex, or quadruplex breaker. This practice is called CTL or circuit limiting.

You can either play along and use two of the five bottom rows. Or you can search for a "non-conforming" breaker. From Murray's product list, it's not clear that they make one. The tab could also be physically ripped out or cut. But of course that would violate code, and if you do it wrong, you could die. And that's no fun.

  • LOL I would have to agree with that no fun part. 😉 – ArchonOSX Feb 1 '16 at 21:07

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