What is wrong here

[Toros]

Hi
Would tell me what is wrong with my design of the service for an apartment complex
See attached
Tanx

 

[GoldDigger]

Two confirmations please:
Is the service really 120/240 4-wire three phase (high leg delta) with only the house panel having access to the high leg?
And is the 350 MCM calculated using the reduced size service wire allowances? You could not, IMHO, apply that when feeding multiple units and house.
If the wiring is full ampacity, I do not see a problem.

 

[LEO2854]

Hi
Would tell me what is wrong with my design of the service for an apartment complex
See attached

Tanx

Okay I posted the image as a picture, because the PDF was a trip to open:lol:

So I hope the picture is large enough:thumbsup:

......

It seems to look god to me..:thumbsup:


,,,,,,,,

 

[augie47]

My first thought was along the line of Golddigger's question.
3 phase 240/120 ?? with a high leg ??
Secondly, the 3/0 neutral you show between neutral bars.. is it in a conduit by itself ?
Third: What is the "OH Pull" ? is this a disconnect/overcurrent device or simply a pull box ?
Last: I'm concerned about your 90amp feeders. 225.39(C) would require
a 100 amp rating.

 

[Ponchik]

Two confirmations please:
Is the service really 120/240 4-wire three phase (high leg delta) with only the house panel having access to the high leg?
And is the 350 MCM calculated using the reduced size service wire allowances? You could not, IMHO, apply that when feeding multiple units and house.
If the wiring is full ampacity, I do not see a problem.

Maybe I am missing something, but how is he reducing the service conductors? he has (2) 350MCM each rated at 310Amps.

On a second note, but nothing wrong, the GEC to the CCE does not have to be 3/0.

 

[Ponchik]

My first thought was along the line of Golddigger's question.
3 phase 240/120 ?? with a high leg ??
Secondly, the 3/0 neutral you show between neutral bars.. is it in a conduit by itself ?
Third: What is the "OH Pull" ? is this a disconnect/overcurrent device or simply a pull box ?
Last: I'm concerned about your 90amp feeders. 225.39(C) would require
a 100 amp rating.

225.39(C) talks about "one family dwelling" I don't think it applies to this since this is a "dwelling unit". At least based on article 100 that is how I see the definition.

 

[bob]

Does SUB p1 & p2 have a main breaker? SUB panel ratings?

 

[GoldDigger]

Maybe I am missing something, but how is he reducing the service conductors? he has (2) 350MCM each rated at 310Amps.

On a second note, but nothing wrong, the GEC to the CCE does not have to be 3/0.

I did not say he did. I did not have my book and so I asked.

 

[Toros]

more-detailed 1-line of an apartm. bldg

more-detailed 1-line of an apartm. bldg

Now , what is wrong here??

See attached please

Tanx

 

[jumper]

Toros, I merged your threads since they deal with the same issue.

 

[jumper]

1. Why a ground rod? Not needed AFAIK.

2. 32,000A service? Typo I imagine.

 

[Smart $]

1. Why a ground rod? Not needed AFAIK.

Agree.

2. 32,000A service? Typo I imagine.

I believe it's 32kA SCCR.

 

[ron]

Bring all 3 phases to the apartment meter bank and then pick off the phases alternating, so the service will be somewhat balanced across phases.

 

[david luchini]

Bring all 3 phases to the apartment meter bank and then pick off the phases alternating, so the service will be somewhat balanced across phases.

It's a 240/120V delta.

 

[ggunn]

It's a 240/120V delta.

Why? Is the HVAC three phase? What else would use the high leg? Why not transform it down to 208 so that the load can be balanced?

Caveat: I am an engineer, not an electrician. Be gentle with me.

 

[Smart $]

Bring all 3 phases to the apartment meter bank and then pick off the phases alternating, so the service will be somewhat balanced across phases.

Why? Is the HVAC three phase? What else would use the high leg? Why not transform it down to 208 so that the load can be balanced?

Caveat: I am an engineer, not an electrician. Be gentle with me.

Perhaps service transformers are open delta with large lighter, small stinger. 3? balancing would actually create a problem.

Service conductor sizes for neutral and high leg could possibly be reduced to match maximum unbalanced load for neutral and load/OCPD-rating for high leg.

 

[JoeStillman]

That 4-wire delta wouldn't fly here in Peco territory. Too much load on the A-C phase. I would use 208V 3?, 4W. The apartments can still be 1?, 3W. Connect 2 to A-B, 2 to B-C and the big one to C-A. You can get a 3? meter center with single phase branches.

 

[Smart $]

That 4-wire delta wouldn't fly here in Peco territory. Too much load on the A-C phase. ...

How can you tell there's too much load???

Summed multiple service OCPD ratings are permitted to exceed the ampacity of service entrance conductors.

 

[GoldDigger]

I think he was perhaps referring to the unbalanced load, with no way to balance it.
POCO can put in a large lighting pot, but there will still be unbalance on the primary side.

 

[Smart $]

I think he was perhaps referring to the unbalanced load, with no way to balance it.
POCO can put in a large lighting pot, but there will still be unbalance on the primary side.

Yeah, but they usually keep track of several such open deltas on their primary and rotate the phases to balance their primary.