A MAIN BREAKER feeding an ATS, is "LSI" required?

[stuartdmc]

Does a Main breaker need to be equipped with Digital-trip "LSI" feeding my 200amp ATS from the gen-set?

The main 3000 amp service has a GFP device feeding a SWBD that feeds the ATS, but from the Gen-set there's no GFP, can i use just use a LS trip unit in that breaker?

Using section 215.10 the service is under 1000 amps therefore a GFP isn't required, Correct?

 

[ron]

You need the "I" too. Instantaneous protection is needed for most ATS's since they do not have 30 cycle ratings

 

[steve66]

If its a hospital, and you have GFP on the main, you need another level of GFP on the feeders. This is to keep a fault on a single feeder from tripping the main.