Circuit Total Limitation
Encyclopedia
Circuit total limitation (CTL) is one of the present-day standards for electrical panels sold in the United States according to the National Electrical Code. The 1965 edition of the NEC, article 384-15 was the first reference to the circuit total limitation of panelboards. , the location of this language is at Article 408.54.
Reputable manufacturers have not made non-CTL panels since 1965.
People are able to go to their local hardware or "big box" home improvement store, and purchase "cheater" breakers that are actually for "replacement use only" in pre-1965 panelboards.
As a result, numerous unsafe situations have resulted where panels were dangerously overloaded because these non-CTL breakers continue to be sold. 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.
Reputable manufacturers have not made non-CTL panels since 1965.
'Non-CTL replacement only' circuit breakers being installed in CTL panels
Circuitboards/panelboards built prior to 1965 do not have circuit total limiting devices or features built into them. Even so, pre-CTL circuit breakers "for replacement use only" continue to be sold to the general public, even to this day.People are able to go to their local hardware or "big box" home improvement store, and purchase "cheater" breakers that are actually for "replacement use only" in pre-1965 panelboards.
As a result, numerous unsafe situations have resulted where panels were dangerously overloaded because these non-CTL breakers continue to be sold. 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.