# equipment grounding outdoor service transformer



## don_resqcapt19 (Jul 18, 2010)

Where is the service point?


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## unsaint32 (Sep 7, 2012)

don_resqcapt19 said:


> Where is the service point?


on the secondary side, which makes it "service-supplied."


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## RePhase277 (Feb 5, 2008)

Are you talking about a utility transformer? If so, it isgrounded by connection to the primary ground and the secondary neutral.

If this is a transformer supplied by building wiring, then it is grounded by the equipment ground ran with the feeder, and by connection to the secondary neutral and electrode.


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## unsaint32 (Sep 7, 2012)

InPhase277 said:


> Are you talking about a utility transformer? If so, it isgrounded by connection to the primary ground and the secondary neutral.
> 
> If this is a transformer supplied by building wiring, then it is grounded by the equipment ground ran with the feeder, and by connection to the secondary neutral and electrode.


Thanks InPhase. That makes sense. 

However, I don't understand the difference between the utility transformer and transformer supplied by building wiring. In both situations, the enclosures are connected to the primary ground and the secondary neutral.


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## backstay (Feb 3, 2011)

unsaint32 said:


> Thanks InPhase. That makes sense.
> 
> However, I don't understand the difference between the utility transformer and transformer supplied by building wiring. In both situations, the enclosures are connected to the primary ground and the secondary neutral.


The difference is the utility takes care of their equipment, NEC starts at the load side of the meter, at least here it does.


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## BBQ (Nov 16, 2010)

backstay said:


> The difference is the utility takes care of their equipment, NEC starts at the load side of the meter, at least here it does.


Exactly, it is on the utility side of the service point so 'we' don't do anything.


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## unsaint32 (Sep 7, 2012)

Regardless of who is responsible, as far as grounding configuration goes, there is no difference then?


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## RePhase277 (Feb 5, 2008)

unsaint32 said:


> Regardless of who is responsible, as far as grounding configuration goes, there is no difference then?


Right. The ground of the high voltage utility supply is tied to the grounded center point of a wye transformer somewhere, and then at every distribution transformer it is tied to the secondary neutral.

Inside a building, the primary ground is tied to the center of a wye transformer, and then to the secondary of every transformer, so yeah. It is basically the same.


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