Non-CTL Replacement Only
Circuitboards and panelboards built prior to 1965 do not have circuit total limiting devices or features built-in. Even so, pre-CTL circuit breakers "for replacement use only" are still sold in local hardware stores. As a result, numerous unsafe situations have resulted where panels were dangerously overloaded because these non-CTL breakers continue to be used. With overuse of non-CTL breakers, current is being placed on the panel's bus-bars in excess of the designed capacity of that panel.
The 2008 code did away with the previous 42 circuit limitation on panelboards. One can now order panelboards with as many as 84 circuit places, and a corresponding ampacity rating. If a panelboard with a sufficient number of breaker positions is installed in the first place, the need for non-CTL breakers should be eliminated.
Read more about this topic: Circuit Total Limitation
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