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plove79 09-01-2010 08:22 AM

Murray main lug center - what type of tandem breaker? cl or ncl?
I have a Murray LC2040L1125 main lug center as my main service panel in my house. Main line directly from meter comes in through two pole backfed 100A main. There are extra spaces in this load center, and it currently only has 19 circuits on it, far less than the 40 that are allowed.

Question: While I was at home depot yesterday, I noticed that there was a 15/15 tandem for $10 and a 15/15 tandem for $18. One was called "CL" ($10) and the other was "NCL" ($18). The person in the electrical department described the difference as the size of the socket that clicks in to the panel. She suggested that I simply buy both and return the one that doesn't fit.

Does anybody have experience with this load center? Can somebody suggest which breaker to buy?

Second question: Should I get the "Main Breaker Kit" (MBK100M: $120) so that I could remove the backfed main and create an actual main for this load center? OR, is this backfed breaker alright? It DOES shut off all electric in the house with one hand motion.


McSteve 09-01-2010 12:19 PM

On the second question, the backfed main is fine, as long as it is mechanically fastened in place so it can't simply be pulled off of the busbars. There should be some kind of hold-down kit installed to keep it in place.

jbfan 09-01-2010 04:50 PM

On the first question, if you have all those spaces, why conside a tandom?
If it is a true 40 circuit panel, then it would not take a tandom.

Stubbie 09-01-2010 05:01 PM

1 Attachment(s)
That Murray panel has 20 full size spaces and takes tandems in all spaces which would give you 40 single pole 120 volt branch circuits.

So 20 full size single pole breakers or 20 tandem single pole breakers.

CL means circuit limiting and those breakers have rejection tabs and will not let you install them in panels that do not allow tandem breakers.

NCL means non circuit limiting and can be installed in a panel that doesn't accept them normally. But you have to be careful to not exceed the maximum number of circuits allowed in the panel your installing them in.

Your panel accepts tandems so buy the CL

frenchelectrican 09-01-2010 08:08 PM

The backfeed main breaker is common as long you use the lockdown kit to hold the breaker in place and yeah it is legit.

Now Stubbie expain very clear between the NCL and CL breakers and yes there is diffrence on price as well.

So if you notched bussbar then yes you can use it if non notched bussbar you have to use diffrent breaker but few case look at the breaker holder as well few case they will have rejetion tab as well so check that as well.


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