Why do they make this breaker?

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jim dungar

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e57 said:
Its a frame size - all of the breakers in that frame size will be the same. Go to the next frame size - bigger... They are sized by Amperage and AIC - not the number of poles - while you might be hard pressed to find a single pole CB the over 100A I don't think I've seem them*, 2-3 poles are all 3 pole cases of that frame no matter if there are 2 or 3 poles of the breaker actually in it.

*See page 12
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In Square D I-Line construction AIC rating does not affect the size of the breaker. Frame size (maximum amps) does. The nominal 100 and 200A frames are normally supplied in 2-pole widths (3") except for the special corner-grounded ones in the OP.
 
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e57

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San Francisco, CA
jim dungar said:
In Square D I-Line construction AIC rating does not affect the size of the breaker. Frame size (maximum amps) does. The nominal 100 and 200A frames are normally supplied in 2-pole widths (3") except for the special corner-grounded ones in the OP.
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I think we're saying the same thing differently?? Most of the frame breakers seem to be available in the same amperage ranges and not often in the same AIC levels. And vise versa... Depends on what they can stuff in there so it seems. The frame size have a max, but even then other frames have same max ratings, but often not available in an AIC you want it seems to me, so I figure it both... Then I assume some just out of convenience.

Anyway - I often see 3 pole cases with nothing in one of them - as 2 poles. As it seems the OP has...
 
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hurk27

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Portage, Indiana NEC: 2008
kwired said:
They used two grounded phases (on the breakers) and the corner ground (on the grounding bus) to get all three phases for the 3 phase load.
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Two grounded phases? H'mmmmm

the NEC used to not require a breaker in the grounded "B" phase, smaller AIC services, we used to just use single phase panels and land "B" on the neutral buss, and two pole breakers for "A" and "C" phases, for higher AIC ratings we used the I line with the missing "B" phase lugs in the same way, but landed "B" on the neutral as well, as far as using these for a high leg panel, maybe to feed a single phase sub panel or a 240 volt load that also used a neutral, but if you were not careful you could still wind up landing the wrong leg on the wrong phase, so I don't see it specifically for a high leg delta.
 
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hurk27

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Portage, Indiana NEC: 2008
Jim weren't these breakers the ones you could move the clips to choose which phase the pole is on? I asked this as I see the phase labels in the OP's picture don't line up with a normal panel, I know the old Sq-D round bus one pole breakers you could do this?
 
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jim dungar

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e57 said:
Anyway - I often see 3 pole cases with nothing in one of them - as 2 poles. As it seems the OP has...
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For 480V applications it is true for all breakers >100A. 240V breakers are available in 2-pole widths through a nominal 250A.

I did just notice that the new HJ breaker, a higher AIC than an HG, is also a 3-pole module for 2-pole applications.
 
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jim dungar

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PE (Retired) - Power Systems
hurk27 said:
Jim weren't these breakers the ones you could move the clips to choose which phase the pole is on? I asked this as I see the phase labels in the OP's picture don't line up with a normal panel, I know the old Sq-D round bus one pole breakers you could do this?
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You have never been allowed to 'field' move the clips of an I-Line breaker.

By your description of a "round bus", I believe you are thinking of their QMB fusbile switch line, which did allow field conversions.
 
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