Beatrice Lang
CTL, or Circuit Total Limiting, is a feature of electrical panels that limits the number of tandem circuit breakers that can be installed. This feature was first mandated by the 1965 edition of the National Electrical Code (NEC) to prevent overloading and the potential risk of fire. Non-CTL breakers, which predate CTL circuit breakers, are still produced for older electrical installations that do not have CTL features.
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What You'll Learn
CTL stands for Circuit Total Limiting
Tandem breakers are 2-in-1 breakers that can double the number of available circuits in a panel board. Before the introduction of CTL, there was no restriction on the number of tandem breakers that could be installed in a panel board, leading to potential overloading and safety hazards. With CTL, electrical panels are designed to have sections that allow single circuit breakers in some slots and CTL tandem circuit breakers in others. The distribution of these slots can be checked in the diagram provided by the panel manufacturer.
It's important to note that CTL breakers come in two main types: CH and BR breakers. CH breakers, made by Cutler Hammer, are slimmer, have tan or black handles, and come with a lifetime warranty. On the other hand, BR breakers, made by Bryant, are thicker, have black handles, and offer a 10-year warranty. Both types are CTL breakers, but it's essential to ensure compatibility with your specific panel.
Non-CTL breakers are still available and used for older electrical installations that do not have CTL features. These non-CTL tandem breakers are labelled for "replacement use only" and are not approved for use in CTL assemblies. However, using these non-CTL breakers can lead to unsafe situations as they can bypass the rejection feature, resulting in panel overloading.
In summary, CTL, or Circuit Total Limiting, is an essential safety feature in modern electrical panels that helps prevent overloading and potential fire hazards by limiting the total number of circuit breakers, including tandem breakers, that can be installed.
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Non-CTL breakers can be used to override CTL features in new panels
CTL stands for Circuit Total Limiting, and it is one of the electrical safety features developed to deliver electricity to your home properly. It is a physical way to prevent overloading a panelboard and risking damage to the wirings of a house.
A class CTL panelboard is designed to have sections that allow single circuit breakers in some slots and CTL tandem circuit breakers in others. The CTL distribution of the slots can be checked in the diagram provided by the panel manufacturer.
Non-CTL breakers are still safe to use as long as they are used as intended. They are still produced today as replacements for tandem breakers for older installations. Non-CTL breakers can be used to override CTL features in new panels. They can bypass the CTL feature of a CTL panel and still allow the breaker's installation on sections not intended for tandem circuit breakers.
However, using non-CTL breakers in CTL panels defeats the safety provided by CTL features and runs the risk of overloading. Non-CTL breakers are also significantly more expensive than CTL breakers. They can reach twice or thrice the prices of CTL breakers.
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CTL breakers come in two types: CH and BR
CTL, which stands for Circuit Total Limiting, first appeared in the 1965 National Electrical Code (NEC). CTL breakers come in two types: CH and BR. These two breakers are named after the companies that made them.
CH breakers (made by Cutler Hammer) are slim and have tan or black handles. They also come with a lifetime warranty. BR breakers (made by Bryant) are thicker and have black handles. They come with a 10-year warranty.
Both CH and BR breakers are CTL breakers, but it's important to check that the breaker you choose is compatible with your electrical panel. Newer panels typically use CTL breakers, while older panels (pre-1965) use non-CTL breakers. If you're unsure, it's best to consult a certified electrician for help.
Non-CTL breakers can be used in tandem with CTL breakers in class CTL panel boards. These panel boards are designed to allow single-circuit breakers in some slots and CTL tandem circuit breakers in others. The CTL distribution of the slots can be checked in the diagram provided by the panel manufacturer. For example, a CTL panel may have a notch at the bus finger on the slots intended for tandem breakers, allowing a CTL tandem breaker to latch on. Slots without the notch cannot hold a CTL breaker.
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CTL was first mandated by the 1965 National Electrical Code
CTL, or Circuit Total Limiting, was first mandated by the 1965 National Electrical Code (NEC). The 1965 NEC was 433 pages long and cost $1.00 per copy. It was published by the National Fire Protection Association (NFPA), which had been publishing the Code since 1911.
Prior to 1962, the NEC Code books did not contain a copyright notice or licensing provision. However, in 1956, the NFPA put a copyright notice on their NEC book and granted permission for governing bodies to adopt and freely reprint the Code. In 1962, the National Board of Fire Underwriters added a statement to their printing of the NEC, acknowledging that the text was copyrighted by the NFPA.
In 1965, the NFPA became the sole producer of the NEC, discontinuing the publication of the Code by the American Insurance Association (formerly the National Board of Fire Underwriters). The NFPA either published the Code itself or received license fees for republications. From 1965 to 1968, the Compson Code Company of Landsing, Michigan, offered a separate printing of the 1965 NEC. From 1965 to 1975, the McGraw-Hill Book Company also printed the National Electrical Code Handbook, though it is unclear if they paid royalties or license fees.
The 1965 NEC introduced the requirement that panelboards must have a physical way to prevent installing too many overcurrent protection devices beyond what the panelboards were designed, rated, and listed for. This was achieved through the use of CTL breakers, which come in two main types: CH (made by Cutler Hammer) and BR (made by Bryant). CTL breakers have safety features that prevent overloading, which is not the case with non-CTL breakers. As a result, newer panels use CTL breakers, while older, pre-1965 panels use non-CTL breakers.
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Non-CTL breakers can lead to panels being dangerously overloaded
CTL stands for Circuit Total Limiting and is one of the standards for electrical panels sold in the United States. CTL is a safety feature designed to prevent overloading a panelboard and risking damage to the wiring of a house.
Non-CTL breakers can fit into any slot in a panel, whereas CTL breakers can only fit into specific slots. This means that it is possible to install too many non-CTL breakers into a panel, overloading it. This can cause the main breaker to open frequently and may lead to a breakdown of the circuit.
To prevent this, CTL breakers have physical means or rejection features to prevent the installation of too many tandem circuits. For example, CTL breakers may have a notch at the bus finger on the slots intended for tandem breakers, which allows a CTL tandem breaker to latch on. Slots that do not have this notch cannot hold a CTL breaker, preventing its installation.
It is important to note that non-CTL breakers are still safe to use as long as they are used as intended. However, using non-CTL breakers in CTL panels defeats the safety provided by CTL features and increases the risk of overloading.
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Frequently asked questions
CTL stands for Circuit Total Limiting.
CTL breakers limit the number of tandem circuit breakers that can be installed into them, preventing overloading. Non-CTL breakers do not have this restriction and can be installed in any slot in a panel.
CTL was introduced in 1965 to prevent panels from being overloaded, which could lead to overheating and potential fires.
CTL breakers come in two main types: CH (made by Cutler Hammer) and BR (made by Bryant). CH breakers are slimmer, have tan or black handles, and come with a lifetime warranty. BR breakers are thicker, have black handles, and have a 10-year warranty.
