What kind of breaker is this?

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evil_adm1n said:
Not seen one of these yet. I saw it when cutting power to a failed AC system. I ran across these in a square D I line distribution panel. Building built mid 70s. Had high leg delta for those interested.

http://i.imgur.com/DICJQ.jpg

http://i.imgur.com/x2UA3.jpg
Click to expand...
Can't be certain, but the lever part of the handle appears to be broken off on the single-pole breaker. Can't be certain whether the same is true of the two-pole breaker. The pic is too grainy.
 
It almost looks like you would insert some sort of key to operate the mechanism.
 
Those are defiantly not I line breakers, or an I line panel, that is a QO or QOB panel, may be a special blank to prevent the hi leg from being used in certain positions. Since the picture doesn't show the whole panel, it's hard to tell. There was one year that tamper resistant breakers were used that had one way screws holding the breakers in. It was not very well thought through, because you could not replace the breaker if it went bad. If I remember correctly, it was around the late 60's or early 70's when this was tried.
 
OP says it an I-Line. I have installed a lot of them with this accessory installed, mostly in school HVAC plants where you have maybe 1-120 volt convenience circuit and 2-120 volt lighting circuits. Most will accept 6 QO single poles, so three come blanked with these.
 
None of pictures are at good angle to see any detail where the handle should be on a typical breaker. Is there a key slot in that area that would mean the user needs a key to operate the device (but it would still automatically trip when necessary of course). They still make key operated versions they are different but may have changed over the years.

Wild leg is in C phase - there are no single pole breakers installed in any C phase slots, and even a double pole that avoids that slot. I don't think you have an I-Line panel. You only show part of panel - there could be this section and a section that accepts I-Line breakers. This section is definately QO or QOB, I am assuming you are mostly questioning the apparent missing handles.
 
You do not have an I-Line. You have a type ML panel.

Based on the handle design, the bigger breaker, the ones that are double wide, appear to be A1B breakers (a 'spec grade version of the QO, they were refered to a E-frame breakers).

The handle-less breaker are key-operated, just like the some 'security' light switches.

Your panel dates back to at lteast the early 60's.
 
Absolutely no doubt about what they are.

Key operated breakers. - If they are double wide, they are A1B style, if they are single wide then they are QO.
 
The single pole 20 amps are part #A1B120. I still believe these are space fillers. I have some at my shop I believe.

The keyed breakers have a hole for the operating lever, like this.


QOK 0730-0143-58_lres.jpg
 
masterinbama said:
The single pole 20 amps are part #A1B120. I still believe these are space fillers. I have some at my shop I believe.

The keyed breakers have a hole for the operating lever, like this.
Click to expand...

Sorry but that is a picture of a new generation QO-K breaker.

The original key operated breakers had a key that looked similar to the key for light switches. The key was inserted flatwise into the breaker.

The 'dummy breaker' space filler (QO1DB) has a flat front.
 
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