Establishing a ground on the secondary side of a transformer

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A 75kVA transformer is being installed in an old existing multi-story building. I am trying to figure the best way to establish the ground on the secondary side of the transformer. There is no building steel (all concrete building), we are unable to use the water pipe, we are three levels up and the path to the main electrical room is almost unattainable. Do I have any other options? Can I connect the ground to the ground bus bar of the distribution board feeding the transformer? If so, do I need to run a seperate conduit?
 
The transformer secondary must be bonded to the metal water piping system. There is an exception that allows bonding to the structural metal of the bulding when it is bonded to the water pipe and is a grounding electode. Since you have no bonded steel in the vicinity of the seperately derived system you would need to bond directly to the metal water piping system. Look at 250.104(D):


250.104(D) Separately Derived Systems. Metal water piping systems and structural metal that is interconnected to form a building frame shall be bonded to separately derived systems in accordance with (D)(1) through (D)(3).
(1) Metal Water Piping System(s). The grounded conductor of each separately derived system shall be bonded to the nearest available point of the metal water piping system(s) in the area served by each separately derived system. This connection shall be made at the same point on the separately derived system where the grounding electrode conductor is connected. Each bonding jumper shall be sized in accordance with Table 250.66 based on the largest ungrounded conductor of the separately derived system.
Exception No. 1: A separate bonding jumper to the metal water piping system shall not be required where the metal water piping system is used as the grounding electrode for the separately derived system.
Exception No. 2: A separate water piping bonding jumper shall not be required where the metal frame of a building or structure is used as the grounding electrode for a separately derived system and is bonded to the metal water piping in the area served by the separately derived system.
(2) Structural Metal. Where exposed structural metal that is interconnected to form the building frame exists in the area served by the separately derived system, it shall be bonded to the grounded conductor of each separately derived system. This connection shall be made at the same point on the separately derived system where the grounding electrode conductor is connected. Each bonding jumper shall be sized in accordance with Table 250.66 based on the largest ungrounded conductor of the separately derived system.
Exception No. 1: A separate bonding jumper to the building structural metal shall not be required where the metal frame of a building or structure is used as the grounding electrode for the separately derived system.
Exception No. 2: A separate bonding jumper to the building structural metal shall not be required where the water piping of a building or structure is used as the grounding electrode for a separately derived system and is bonded to the building structural metal in the area served by the separately derived system.
(3) Common Grounding Electrode Conductor. Where a common grounding electrode conductor is installed for multiple separately derived systems as permitted by 250.30(A)(4), and exposed structural metal that is interconnected to form the building frame or interior metal piping exists in the area served by the separately derived system, the metal piping and the structural metal member shall be bonded to the common grounding electrode conductor.
Exception: A separate bonding jumper from each derived system to metal water piping and to structural metal members shall not be required where the metal water piping and the structural metal members in the area served by the separately derived system are bonded to the common grounding electrode conductor.
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"we are unable to use the water pipe, we are three levels up and the path to the main electrical room is almost unattainable."

It is not "unattainable", it is just hard to get to. That is what separates US from the big box store wannabees.
Good Luck!!
 
Okay, I have not researched this and its early on Monday morning, but if he bonds to the ground bar in the distribution panel, would that not be enough since it would effectively connect him to the existing grounding grid, waterpipe, etc.
 
Okay, I have not researched this and its early on Monday morning, but if he bonds to the ground bar in the distribution panel, would that not be enough since it would effectively connect him to the existing grounding grid, waterpipe, etc.
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A grounding electrode is required and the ground bar in the distribution panel is not a grounding electrode.
Don
 
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