ciruit breakers

What is the difference between non-restricted (aka non-circuit limiting?) (e.g. Murray MP2020N) and restricted (aka circuit limiting?) (e.g. Murray MP2020) circuit breakers? And what are the respective uses?

 

The "N" means non rejecting. They are only to replace thin old breakers in old panels. New thin breakers won't fit because they require a notch in the bus bar. A lack of a notch in a new bus bar is used to reject thin breakers so that you don't over fill the panel beyond its design. When you order a Murry panel it will have a number such as 12/24 which means it will accept 12 full size single pole breakers or 24 of the thin style. All 12 of these positions are notched. But in some panels such as a 30/40 only 10 positions are notched. To fill this panel to capacity you have to use 20 thins and 20 full size. If it weren't for the rejection you could cram 60 thin single pole breakers in there.

 

Hi LouieS,

Thanks for the info. I have a new Murray 20/40 Main Lug Load Box. So, per your input this can hold 40 thin breakers. Do these breakers only come in doubles e.g. 15/15 or can you buy individual thin breakers e.g. 15 ?

 

Right up untill Siemens purchased Murray the thin breakers came in singles but no more. However you can purchase a 15/20 pair. They thought of everything.