Circuit Breaker Selection

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jstpie5

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All,

I am selecting breakers for a 3 phase panel (480/277V I-Line panel) and I came across something I have never thought about before..

There is a selection of AB, BA, BC, CB, CA, & AC for 2 pole breakers.

The question is, what difference does it make to have a AB vs BA breaker? Why would you need a BA phasing over a AB?

The only way I could imagine it makes a difference would be if the panel was fed by a wild-leg transformer.

Your thoughts?
 
Looking at an i line panel from the outside, I would assume the different lugs are for left or right handed installation. I would also presume that they are mirror images of each other. My wag for the day.
 
jstpie5 said:
All,

I am selecting breakers for a 3 phase panel (480/277V I-Line panel) and I came across something I have never thought about before..

There is a selection of AB, BA, BC, CB, CA, & AC for 2 pole breakers.

The question is, what difference does it make to have a AB vs BA breaker? Why would you need a BA phasing over a AB?

The only way I could imagine it makes a difference would be if the panel was fed by a wild-leg transformer.

Your thoughts?
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I had known you had to select connections for 1 and 2 pole in the past - and always thought there were only three choices for each. Just looked in online catalog and seems even three pole now you have option for ABC or CBA. In ~30 years I never worried about three pole breakers at all. But if you want to be strict in NEC enforcement I believe somewhere (maybe in art 110 it says bus and switch arrangements must be left to right ABC, top to bottom ABC and front to rear ABC. I guess I have had many I lines over the years that are wrong if breaker is on the right side of the panel. I'm not going to lose any sleep over it though.
 
kwired said:
I had known you had to select connections for 1 and 2 pole in the past - and always thought there were only three choices for each. Just looked in online catalog and seems even three pole now you have option for ABC or CBA. In ~30 years I never worried about three pole breakers at all. But if you want to be strict in NEC enforcement I believe somewhere (maybe in art 110 it says bus and switch arrangements must be left to right ABC, top to bottom ABC and front to rear ABC. I guess I have had many I lines over the years that are wrong if breaker is on the right side of the panel. I'm not going to lose any sleep over it though.
Click to expand...
Yep, that's the issue. When you plug in a multi-pole breaker to the bus of an I-Line panel, because of the way the bus is oriented in order to make in plug-in compatible, breakers on opposite sides of the panel will be wrong with relation to the requirement for phase terminal orientation, A,B,C top to bottom. So you correct that by having different stab assemblies.
 
kwired said:
I had known you had to select connections for 1 and 2 pole in the past - and always thought there were only three choices for each. Just looked in online catalog and seems even three pole now you have option for ABC or CBA. In ~30 years I never worried about three pole breakers at all. But if you want to be strict in NEC enforcement I believe somewhere (maybe in art 110 it says bus and switch arrangements must be left to right ABC, top to bottom ABC and front to rear ABC. I guess I have had many I lines over the years that are wrong if breaker is on the right side of the panel. I'm not going to lose any sleep over it though.
Click to expand...
I believe the phase arrangement rules only apply to the bus and they do not apply to the breakers connected to that bus. 408.3(E)
 
don_resqcapt19 said:
I believe the phase arrangement rules only apply to the bus and they do not apply to the breakers connected to that bus. 408.3(E)
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Might be correct. I have never been concerned about the need for a CBA breaker to install on right side in an I line panel, and never knew they existed until now.

I did know you had to specify which bus single and two pole breakers connected to, but also didn't know until now that there were six configurations instead of three available for two pole units.
 
Circuit Breaker Selection

JFletcher said:
Looking at an i line panel from the outside, I would assume the different lugs are for left or right handed installation. I would also presume that they are mirror images of each other. My wag for the day.
Click to expand...

Wait, I though all I-Lines are stab-on breakers? Unless there is an older version that bolts on?



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brantmacga said:
Wait, I though all I-Lines are stab-on breakers? Unless there is an older version that bolts on?
Click to expand...

The I-Line bus stack has not changed since it was introduced in the late 60's. There was a breaker style offered that had a screw clamp arrangement, but the actual bus connection was the standard jaw.
 
brantmacga said:
Wait, I though all I-Lines are stab-on breakers? Unless there is an older version that bolts on?



Sent from my iPhone using Tapatalk
Click to expand...
They are, but if you put a three pole breaker on the left side of bus you have ABC from top to bottom on output terminals - place same breaker on right side of bus and output terminals will be CBA from top to bottom.
 
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