non-limiting duplex CB?

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Old 11-09-05, 08:28 AM
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non-limiting duplex CB?

While looking at circuit breakers yesterday I noticed that the duplex breakers come labeled "non-limiting". They are about 50% more than those duplex CBs without that qualification.
What does the non-limiting mean?

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HDIY
 
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Old 11-09-05, 09:01 AM
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Edit: Wrong thread.
 
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Old 11-09-05, 09:02 AM
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The term is 'Circuit Total Limiting' or 'CTL'.

Panelboards are limited to how many circuit breakers they are permitted to have. 'Skinny' breakers physically let you put two circuit breakers in the place of one full sized breaker. But this does _permit_ you to exceed the maximum number of allowed breakers. Because skinny breakers were being abused (and panels overloaded), the class CTL breakers were developed. A class CTL breaker will only fit in particularly places on a class CTL panelboard, preventing you from putting too many breakers in the panel.

Problem is that CTL breakers won't fit in old panelboards, even if they were permitted. So you have more expensive non-CTL breakers that fit older panels. Since they bypass the CTL protection, you have to be careful not to exceed the maximum number of allowed breakers.

-Jon
 
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Old 11-09-05, 01:09 PM
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Thank you.
 
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