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A QO2020 tandem breaker is designed to go into a Non-Class CTL, QO loadcenter. What does this mean?

Product Design feature

Product Line:
QO load centers

National Electrica Code 



Non-Class CTL(Circuit Limiting) panels do not have a rejection feature that would restrict the number of tandem breakers that can be installed into them. As a result, the panel could be overloaded. A code change corrected this for safetyreasons and all load centers (since approximately 1965) must be designed to meet CTL standards. Panels that are not designed to take tandem breakers have a rejection feature to prevent them being installed.

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