LSIG vs LS trip unit for 1200a MCB in PLC

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rise62

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Do I need to have a breaker with LSIG as my main inside a PLC.
It's a 1200amp breaker, can i use just use a LS trip unit in that breaker?
Note that the there is a 1200amp CB w/ LSIG feeding this PLC panel in the same room.

 
You will have to decide what kind of protection you need.

The "I" instantaneous portion of LSIG is needed unless it is feeding something with a 30 cycle short circuit rating, such as SWGR (not regular SWBD).

The "G" ground fault portion is needed if that service requires that type of protection. Look at 215.10 if it is a feeder.
 
If your feeder protection includes LSIG, and the LS device is simply a local disconnect, you would be compliant with the code.
 
The quick and dirty way to look at it is; it does not need GFP if the device AHEAD of it already has GFP. So if there is a main ahead of this, it will be REQUIRED to have GFP, ergo it's a safe bet this one does not. It only gets tricky if this is part of a group of breakers used in a "6 hand rule" situation.

That said, I got nailed once by an AHJ who insisted that because the main switchboard, which had a 3000A Main (with GFP of course) was in another building 40 ft away across the parking lot and the feeder to this building was underground (no idea why that mattered), the 1000A breaker on the MCC that I installed in the new building was considered a new "service entrance" and thereby needed GFP (again). I never understood that one but it was easier to install the GFP on the breaker than it was to argue with the AHJ.
 
Jraef said:
The quick and dirty way to look at it is; it does not need GFP if the device AHEAD of it already has GFP. So if there is a main ahead of this, it will be REQUIRED to have GFP, ergo it's a safe bet this one does not. It only gets tricky if this is part of a group of breakers used in a "6 hand rule" situation.

That said, I got nailed once by an AHJ who insisted that because the main switchboard, which had a 3000A Main (with GFP of course) was in another building 40 ft away across the parking lot and the feeder to this building was underground (no idea why that mattered), the 1000A breaker on the MCC that I installed in the new building was considered a new "service entrance" and thereby needed GFP (again). I never understood that one but it was easier to install the GFP on the breaker than it was to argue with the AHJ.
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Can Ground Fault Protection at two locations cause problems ? Example: Ground Fault Circuit Interrupter protected receptacles fed by a Ground Fault Circuit Interrupter breaker. The GFCI breaker trips & nobody knows or remembers that there is a GFCI device in the basement behind boxes of crap that needs to be reset.

Yes I am aware that GFP & GFCI are two distinct animals.
 
John120/240 said:
Can Ground Fault Protection at two locations cause problems ? Example: Ground Fault Circuit Interrupter protected receptacles fed by a Ground Fault Circuit Interrupter breaker. The GFCI breaker trips & nobody knows or remembers that there is a GFCI device in the basement behind boxes of crap that needs to be reset.

Yes I am aware that GFP & GFCI are two distinct animals.
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Well, it certainly would cause that problem. But while there is no point in doing it, there is also no rule in the NEC that would prevent you from wasting your money like that.
 
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