View source for Circuit total limitation

{{Short description|Present-day standards for electrical panels}}
{{more citations needed|date=March 2009}}

'''Circuit total limitation''' ('''CTL''') is one of the present-day standards for [[electrical panel]]s sold in the United States according to the [[National Electrical Code]].  This standard requires an electrical panel to provide a physical mechanism to prevent installing more [[circuit breaker]]s than it was designed for.  This has generally been implemented by restricting the use of tandem (duplex) breakers to replace standard single pole breakers.

==Code Requirement==
The 1965 edition of the NEC, article 384-15 was the first reference to the circuit total limitation of [[panelboard]]s.<ref>{{ Cite book | title = American Electricians' Handbook | work = 15th Edition |author1=Terrell Croft |author2=Wilford I. Summers |author3=Frederic Hartwell | date = 17 August 2008 | page = 4.52 | publisher = McGraw Hill Professional | isbn = 9780071642583 | url = https://books.google.com/books?id=y-vq2G1lHUMC&dq=(NFPA+OR+NEC)+408.54&pg=PT2144 }}</ref> {{as of|2008}}, the location of this language is at Article 408.54 now titled "Maximum Number of Overcurrent Devices."
Non-CTL panels have not been made by reputable manufacturers since 1965.{{Citation needed|date=March 2009}} Though this may change due to the 2008 repeal.

==Non-CTL for replacement only==

Circuitboards and panelboards built prior to 1965 did not have circuit total limiting devices or features built-in.  To support these old panels, non-CTL circuit breakers that bypass the rejection feature are still sold "for replacement use only."<ref>{{ cite web | title = UL's ''Guide Information for Electrical Equipment: The White Book 2008'' | page = 90 | url = http://www.ul.com/regulators/2008_WhiteBook.pdf | url-status = dead | archiveurl = https://web.archive.org/web/20080913082528/http://www.ul.com/regulators/2008_WhiteBook.pdf | archivedate = 2008-09-13 }}</ref>  As a result, numerous unsafe situations have resulted where panels were dangerously overloaded because these non-CTL breakers continue to be used.{{Citation needed|date=March 2009}}  With the use of non-CTL breakers, panels can be configured with the total number of circuits in excess of the designed capacity of that panel.

The 2008 code did away with the previous 42 circuit limitation on panelboards.<ref>See "bullet" in 2008 NEC between Articles 408.30 and 408.36, where 2005's Article 408.35 appeared.</ref> One can now order panelboards with as many as 84 circuit places, and a corresponding ampacity rating.<!-- <ref>http://ecatalog.squared.com/pubs/Electrical%20Distribution/Panelboards/NQ%20Lighting%20and%20Appliance%20Branch-Circuit%20Panelboards/1600HO0802.pdf {{Dead link|date=March 2022}}</ref> Catalogues are not reliable secondary sources --> 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.

In their 2019 catalog Eaton now specifies that their non-CTL breakers are "Suitable for use in plug-on neutral style loadcenters" <ref>https://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/vol01_tab01.pdf {{Bare URL PDF|date=March 2022}}</ref> which negates the replacement only rule.

== Gallery ==

<gallery>
Image:Cutler-Hammer ONE pole CTL circuit breaker LARGE.JPG|Cutler-Hammer ONE pole CTL circuit breaker
Image:Cutler-Hammer ONE pole CTL Circuit Breaker CLOSEUP.jpg|Cutler-Hammer ONE pole CTL Circuit Breaker close-up
Image:Cutler-Hammer CHEATER or Non-CTL Circuit Breaker LARGE.JPG|Cutler-Hammer CHEATER or Non-CTL Circuit Breaker
Image:Cutler-Hammer CHEATER or Non-CTL Circuit Breaker CLOSEUP.jpg|Cutler-Hammer CHEATER or Non-CTL Circuit Breaker
Image:Cutler-Hammer TWO pole CTL Circuit Breaker LARGE.JPG|Cutler-Hammer TWO pole CTL Circuit Breaker
Image:Cutler-Hammer TWO pole CTL Circuit Breaker CLOSEUP.jpg|Cutler-Hammer TWO pole CTL Circuit Breaker
</gallery>

==See also==
* [[National Electrical Code]]

==References==

{{reflist}}

== External links ==

* {{cite web | work = National Electrical Code 2008 | title = Removal of 42 Circuit Limitation for Lighting and Appliance Panelboards". | url = http://ecatalog.squared.com/techlib/displaydocument.cfm?id=1600DB0701&action=view }}{{dead link|date=August 2017 |bot=InternetArchiveBot |fix-attempted=yes }}

[[Category:Electrical engineering]]
[[Category:Electrical wiring]]
[[Category:Electric power distribution]]