GFP on 2000A Main

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zog

Senior Member
Location
Charlotte, NC
Please give me a break, you've got to be kidding, leave the engineering to engineers, and what ever 'aghast' comments I can think of.

The GFP absolutely may be able to be coordinated with the branch circuit breakers. In fact, I don't think I have never been able to coordinate with 30A, and some times higher, branch devices.
Right, but just because it is set at the minimum does not mean the solution is to turn it up. That is what has happend in this thread I think.
 

hurk27

Senior Member
All I know is when to engineer did the study he said he used the closest panel with the highest available fault current and set it to only open if a fault happens ahead of this panel, not after, he said that was what the local breakers are for, before this it would trip if an extension cord was plugged in and shorted, But he did say that he had no clue why there was a GFP on the main of the 120/208 system, as its not required by code, and could be set all the way up, but said it was better to have it, as it would limit the available fault current on the grounding.

This was related to this post I made awhile back:2K amp GE Power Break 2 W/GFP
 

brian john

Senior Member
Location
Leesburg, VA
Every so often we run into GFP on 208/120 wye, not sure the thought process that goes into this and the ones I have dealt with all had no coordination study, which was why we were there (nuisance tripping).

Engineering firms really need to deal with this as part of the project or at a minimum note it on the drawing or specs, informing the EC he needs to hire a firm to perform the study.
 

iwire

Moderator
Staff member
Location
Massachusetts
Right, but just because it is set at the minimum does not mean the solution is to turn it up.
But no one here has said to 'just crank it up'.

We all said have an engineer look into it, then you looked down at all of us and said .....

Well then there is nothing to coordinate it with, you don;t need a study, and it should be set to the lowest setting.
We can't tell if they should be at the minimum settings and I very much doubt they should.


If only the main has GF then there is nothing to coordinate it with now is there? It should be set to the minimum setting, which is the same thing you just said, so I have no idea why you think we are talking about different things.
All breakers on a grounded system provide a level of ground fault protection even if the settings are not adjustable, the breakers on the supply side must be coordinated.

No?
 

zog

Senior Member
Location
Charlotte, NC
I had a situation about a week ago on a service call to a warehouse with 480v mh high bays. A high resistance ground fault in one of the high bays was tripping the gfp on the 2000A main instead of the branch circuit OCD. .
I have yet to see one that has been set until they start having problems. The factory default settings are always at minimum
Yes, you are correct..... factory gfp setting at 200A. Thanks guy's!
To me this sounds like the OP found the GFP set at the minimum setting and turned it up. Maybe I am interpreting this wrong.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Engineer
To me this sounds like the OP found the GFP set at the minimum setting and turned it up. Maybe I am interpreting this wrong.
I agree the OP acknowledged finding the settings at minimum. However, the OP made no comment at all about changing the settings. He simply thanked us for our advice, which has consistently been to have the proper settings be determined.
 
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