Point of Service Entrance

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TABears

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Electrician, Electrical Project Manager, Electrical Engineering.
Good day,

There is some debate going on about where is the first main disconnect to the hospital project i'm working on.

The UK engineers have added a new 5MVA 4160:480V transformer and associated switchgear to the building to meet the contractual obligations for redundancey. The project is in a British Overseas Territory, however the NEC is the adopted code for the jurisdiction.

The new system adds a new 5mVA 4160:480/277 transformer, diverts the oyutputs from the original 2.5mVA transformers to (2) "Changeover Panels" The new 5mVA transformer feeds both Changeover Panel A & B, the change overs are basically 4000A transfer switches for the utility feeds. These are ahead of all the building distribution, normal ATS s for Critical Branch Equipment Branch, Generator Sync Board etc.

MEDIUM VOLTAGE EQUIPMENT, DISCONNECT AND TRANSFORMERS ARE PROPERTY OF THE HOSPITAL.

INTENT OF TX-3 AND CHANGEOVER PANELS A & B IS IF EITHER TX1 OR TX-2 SHOULD LOSE ITS UTILITY FEED THE CHANGE OVER PANELS WILL TRANSFER THE LOAD TO THE TX-3 FEED AUTOMATICALLY. BASICALLY THE CHANGEOVER PANELS ARE TRANSFER SWITCHES ON THE UTILITY FEEDS.

THE QUESTION IS, IS THE SERVICE ENTRANCE POINT CHANGEOVER PANELS A & B IN THE NEW CONFIGURATION?
THE UK ENGINEER WANTS TO LEAVE THE NEUTRAL TO GROUND BOND IN THE MLV BOARD AND WE BELIEVE IT SHOULD NOW BE IN CHANGEOVER PANELS A & B .

Do these Changeover panels become the first main disconnects in the building. Turning off each of the 4000A switches in A & B disconnects the entire building from the utility.

I have a drawing I did for clarification, I just can't aatch to the thread.
 
Service Point. The point of connection between the facilities of the serving utility and the premises wiring.
Informational Note: The service point can be described as the point of demarcation between where the serving utility ends and the premises wiring begins. The serving utility generally specifies the location of the service point based on the conditions of service.

Side-note: Please update your profile to indicate your relation to the electrical industry (engineer,, contractor, electrician, etc.)
 
augie47 said:
Service Point. The point of connection between the facilities of the serving utility and the premises wiring.
Informational Note: The service point can be described as the point of demarcation between where the serving utility ends and the premises wiring begins. The serving utility generally specifies the location of the service point based on the conditions of service.

Side-note: Please update your profile to indicate your relation to the electrical industry (engineer,, contractor, electrician, etc.)
Click to expand...
The utility actually ends their supply to the customer at the sub station on the compound. The substation, medium voltage switchboard etc are all property of the hospital. The point I'm trying to make is (my opinion) the service entrance is the first disconnect in the building after the MV transformers, which would be in the new changeover switches, not in the existing main low voltage switchboard. Does that make any sense?
 
It makes sense but, based on the NEC definition, the service disconnect would be the 1st switch connected after the service point.
IMO it would be the primary switch on the customer owned transformer

One of Mike's slides:
1697043605902.png
 
Ok so bonding the ground to the neutral, would that be in the changeover switches or the main low voltage switchboard? Currently it's still in the MLV I'm going by NEC2023 Exibit 250.5 pg 220 in the hardcover handbook.
 
TABears said:
The utility actually ends their supply to the customer at the sub station on the compound. The substation, medium voltage switchboard etc are all property of the hospital. The point I'm trying to make is (my opinion) the service entrance is the first disconnect in the building after the MV transformers, which would be in the new changeover switches, not in the existing main low voltage switchboard. Does that make any sense?
Click to expand...
I am with you on this. We have a client that has a MV loop feed around their campus and they own all of the step down transformers that go from MV to LV (480V). They have 8 buildings and all of the first means of disconnects are the LV mains at each building and not the MV switches that they also own.
 
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