Ground Fault Protection of Equipment

Strathead said:
I don't understand the context of your statement. The OP was asking about the 2000A breakers not the 4000A
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Post 4 asks about GFPE on the 4000 amp breakers. Post 5 from the OP says the 4000 amp breakers are on the 208/120 volt system. Then post 11, which my post 15 replied to.
 
jim dungar said:
The 480V equipment has sections called 'utility tap'. Thus would make the 2000A devices service equipment.
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Agreed, the other confirming concept is, what scenario would call for incoming 208 stepped up to significant 480/277 loads? At these amperages the Utility is going to be supplying new transformers from their medium voltage to the customers needs. Stating at 208 would be poor design.
 
Strathead said:
Agreed, the other confirming concept is, what scenario would call for incoming 208 stepped up to significant 480/277 loads? At these amperages the Utility is going to be supplying new transformers from their medium voltage to the customers needs. Stating at 208 would be poor design.
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Actually, I believe @infinity comes across that in NY where they will only supply 208 and bigger projects the customer needs to step up to 480 (hence my comment in post #19).
 
infinity said:
I believe it's the opposite. The service is 480Y/277.
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But the drawing says the secondary, where the 2000A breakers are, is 480/277… it doesn’t indicate the primary voltage, where the 4000A breaker is. But if that is 13.8kV or something, with a 4000A breaker? That would be one HUGE transformer, with a serious available fault current problem on that 480V bus!!!

Something about that drawing is wrong, we just don’t know what it is yet…

OK, failure of imagination on my part that the primary is 208V… but why would a utility absorb the losses on their side by delivering a 4000A 208V service to a user who needs 480V??? Makes no sense to me.
 
Jraef said:
But the drawing says the secondary, where the 2000A breakers are, is 480/277… it doesn’t indicate the primary voltage, where the 4000A breaker is. But if that is 13.8kV or something, with a 4000A breaker? That would be one HUGE transformer, with a serious available fault current problem on that 480V bus!!!

Something about that drawing is wrong, we just don’t know what it is yet…

OK, failure of imagination on my part that the primary is 208V… but why would a utility absorb the losses on their side by delivering a 4000A 208V service to a user who needs 480V??? Makes no sense to me.
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I think u fell into the same trap I did , thinking the 4000 is the source. That is not the source, it's downstream, after a 480-208 transformer .
 
To me it looks like a 6 main set up.
Each in it's own enclosure.
3- 2000 amp mains ( service disconnects)
1- 800 main ( service disconnect)
1- fire pump tap
The 2- 2000 feeds a transformer with a 4000 amp secondary OCPD feeding buss way.
The other is a 2000 amp feeders.

I would say the three 2000 amp need GFP protection.

Each section switch board has a GEC and a MBJ which they should if the sections are service equipment.

Edit, added the words ( service disconnect)
 
electrofelon said:
I think u fell into the same trap I did , thinking the 4000 is the source. That is not the source, it's downstream, after a 480-208 transformer .
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D’oh! Ok, I see that.

Well, sort of… but if that’s the case, where does MSB1 get its source from? Do they have an 800A breaker feeding a 2000A breaker? Something is still wrong with that one-line. Or maybe I’m just too thick…
 
Jraef said:
D’oh! Ok, I see that.

Well, sort of… but if that’s the case, where does MSB1 get its source from? Do they have an 800A breaker feeding a 2000A breaker? Something is still wrong with that one-line. Or maybe I’m just too thick…
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It looks like there are two 480Y/277V services, one with three mains and the other with two mains. The left service has a metering section while the right service shows just a utility tap section.
 
jim dungar said:
It looks like there are two 480Y/277V services, one with three mains and the other with two mains. The left service has a metering section while the right service shows just a utility tap section.
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I concur and while it is a little harder because we aren't seeing the entire riser, it is pretty plain to me that you have two utility feeds, they are represented by the fainter grey lines at the bottom. One service is 3000A because it taps off to blg 301 and a feed to the transformer and likely and east side tower Bus duct feed the other is a 2000A service that feeds the fire pump house panel and the west riser. Could be north south for those of us who are pedantic.
 
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