Puzzled about Cutler Hammer tandem breaker "1968" description
#1
12-16-12, 12:10 AM
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Puzzled about Cutler Hammer tandem breaker "1968" description
I have a CMBE3242B225BF (similar to panel CMBE3242B200BF) main panel which is designed for 32/42 circuits. The diagram shows 10 of the slots accept tandem breakers, and that's why it can hold 10 additional circuits beyond 32.
But in all of the descriptions for the CHNT tandem breakers it says the following:
"Non-CTL Plug-On Replacement Circuit Breakers, Type CHNT 10 kAIC, 120/240 Vac
For use as replacement in loadcenters built prior to 1968 and within the current style 2–8 circuit loadcenters as indicated in the loadcenter section."
If my new 32/42 circuit panel shows it takes the tandem breakers, then why does the description say that these breakers are for panels built prior to 1968 or panels with 8 or less circuits?
Is this a mistake in all of their product descriptions? It doesn't make any sense.
But in all of the descriptions for the CHNT tandem breakers it says the following:
"Non-CTL Plug-On Replacement Circuit Breakers, Type CHNT 10 kAIC, 120/240 Vac
For use as replacement in loadcenters built prior to 1968 and within the current style 2–8 circuit loadcenters as indicated in the loadcenter section."
If my new 32/42 circuit panel shows it takes the tandem breakers, then why does the description say that these breakers are for panels built prior to 1968 or panels with 8 or less circuits?
Is this a mistake in all of their product descriptions? It doesn't make any sense.
#2
12-16-12, 01:34 AM
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I think I found the answer to my own question - on the tiny print on the panel label, this panel uses CHT type twin breakers, not CHNT. Interesting that this info is not published anywhere, other than the sticker on the panel that eventually weathers and fades over time.
#3
12-16-12, 06:57 AM
Forum Topic Moderator
Newer panels that can accept tandems would use a CTL listed breaker. CTL is circuit tandem limiting. This limits the number of breakers to certain positions in the panel. Otherwise a 40 circuit panel could be filled with up to 80 breakers.
#4
12-16-12, 07:23 AM
Member
This is a pre 2008 formula.
Inspecting Tandem Circuit Breakers | The ASHI Reporter | Inspection News & Views from the American Society of Home Inspectors
Class CTL Panelboards
Panelboards must follow UL Standard 67, which requires all lighting and appliance panelboards to be Class CTL (Circuit Total Limiting). Here's a formula for determining how many circuits are allowed in the Class CTL panelboard being inspected. Take the amperage of the panelboard, multiply by the number of poles, and divide by 10. It sounds complicated, but it's not — let's use a 100-amp panelboard as an example:
100 Amp x 2 Poles = 200
200 / 10 = 20
Panelboards must follow UL Standard 67, which requires all lighting and appliance panelboards to be Class CTL (Circuit Total Limiting). Here's a formula for determining how many circuits are allowed in the Class CTL panelboard being inspected. Take the amperage of the panelboard, multiply by the number of poles, and divide by 10. It sounds complicated, but it's not — let's use a 100-amp panelboard as an example:
100 Amp x 2 Poles = 200
200 / 10 = 20
