help with square D series rating for legacy breaker

[electrofelon]

Yep, you have some overdutied equipment that should be replaced.
Square D started putting labels on the front of their I-Line breakers around 1985. Prior to that the higher AIC 480V devices often had colored handles.

Your main breaker is more than 40 years old, has it ever been tested?

Well not exactly sure what you mean by tested. After starting this thread, I did exercise the breaker And found that the A pole is not opening. Same client had the same problem with the same breaker at another building. Not sure of that is coincidence or there was a flaw with these breakers. So considering all that, the gear needs to be replaced.

 

[jim dungar]

Same client had the same problem with the same breaker at another building. Not sure of that is coincidence...

Molded case breakers 800A frame and larger have been known to 'freeze' if they are not exercised regularly, in many cases this means yearly. These breakers are not designed to be opened and maintained, but the on-off operation keeps the moving parts lubricated. I know several companies that require a replacement or rental (?) breaker be somewhat available before they will even turn an older large breaker on and off. Yeah, $40K is a lot of money, put so is +8 hours of an unplanned outage.

 

[kwired]

Molded case breakers 800A frame and larger have been known to 'freeze' if they are not exercised regularly, in many cases this means yearly. These breakers are not designed to be opened and maintained, but the on-off operation keeps the moving parts lubricated. I know several companies that require a replacement or rental (?) breaker be somewhat available before they will even turn an older large breaker on and off. Yeah, $40K is a lot of money, put so is +8 hours of an unplanned outage.

Seems like a good design would be to use a fused switch in many cases. And yes seems that over 600 amps quite often is fused instead of breakers on what I am seeing.

 

[electrofelon]

Yeah I went through this at their other facility. Sq D wanted 20k to retrofit a new breaker into the gear. I replaced everything with two new panelboards for a little less. Jumping it out and sending it out to be serviced was an option in the previous case but we didnt go that route, and certainly not an option here because of the other deficiencies.

 

[jim dungar]

Seems like a good design would be to use a fused switch in many cases. And yes seems that over 600 amps quite often is fused instead of breakers on what I am seeing.

Larger fused switches, like bolted pressure designs, may have higher rates of seizing up than many breakers, but they are often able to be serviced. In my experience, it is more common to replace old bolted pressure switches than old breakers, especially to reduce AF incident energy.