Breaker frame size
- Thread starter m sleem
- Start date
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- Location
- Massachusetts
It is simply a matter of what is available not a code issue.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Frame size and trip settings are not related.
In the vast majority of situations the frame size is the largest setting the device can handle.
Some 'iron frame' breakers were built with trip settings greater than the frame size (e.g. 1.1X) although I don't remember seeing new installations for the past few decades.
About 50 years ago the typical molded case breaker frame sizes were: 60, 100, 200, 225, 400, 800, 1200, 2000
Now we also see sizes of 150, 250, 600
In the vast majority of situations the frame size is the largest setting the device can handle.
Some 'iron frame' breakers were built with trip settings greater than the frame size (e.g. 1.1X) although I don't remember seeing new installations for the past few decades.
About 50 years ago the typical molded case breaker frame sizes were: 60, 100, 200, 225, 400, 800, 1200, 2000
Now we also see sizes of 150, 250, 600
Jim will correct me if I'm wrong..
but I have seen frame size selected for:
(a) future use (a 1200 amp frame for possible future load but presently with a 600 amp rating plug to protect present wiring)
(b) to address a high fault current situation. At times a small ampere rated breaker will have the frame suitable for a larger
breaker to meet fault-current requirements of the panelboard.
but I have seen frame size selected for:
(a) future use (a 1200 amp frame for possible future load but presently with a 600 amp rating plug to protect present wiring)
(b) to address a high fault current situation. At times a small ampere rated breaker will have the frame suitable for a larger
breaker to meet fault-current requirements of the panelboard.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Still waiting for that to happen.
I understand the breaker with higher withstand capcity would protect easier against the lower currents. In the same time we cannot increase the frame size without ruling. So i would think Jim's ratings ar ok and worked for me.
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