2ND LEVEL OF GROUNDFAULT

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frostback

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HI FOLKS,I AM DESIGNING A 2 STORY AMBULATORY BLDG
THE FIRST FLOOR IS IMAGING,AND DOCTOR OFFICES
WITH EXAM ROOMS THE SECOND FLOOR HAS THE SURGERY
SUITE, OUTPATIENT ONLY,WITH ADDITIONAL DOCTOR OFFICES ON THAT FLOOR.WE HAVE A GEN SET FOR THE SURG SUITE AND ELEV .I HAVE A 3000A SERVICE WITH
GFI ON THE MAIN.WHAT SECONDARY FEEDERS IF ANY, IN THIS FACILITY NEED A SECOND LEVEL OF GFI.
AT THIS TIME I HAVE ALL THE SECONDARY FEEDERS ON
GFI CIRC BKRS.IS THIS OK.
 
Re: 2ND LEVEL OF GROUNDFAULT

Some designers will go for six mains to avoid the expensive main. Is there a reason for one main?

What is the ratio of calculated load to connected load?
 
Re: 2ND LEVEL OF GROUNDFAULT

From what you have described you seem to be compliant with 517.17. All feeders that are the next step down stream from the main need ground fault protection. You must do a coordination study to assure all the breakers trip curves are properly coordinated.

Assuming you have a 480V service if you do what Bennie suggests and go to the 6 disconnect rule, If all 6 are less that 1000A you would not need ground fault protection on any of the breakers.
 
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