Question: If I have a grounding bus in the service entrance room, say room # 1 located on the first floor, that is connected to a water main, structural steel, and ground rods and I connected all the transformer neutrals in this room and the adjacant room to it. Then I routed a 3/0 ground wire to a ground bus located on the third floor in room # 2 and connected all transformers neutrals to that bus bar, do I have still need to connect the bus bar in room # 2 to water pipe?
Multiple bonding and grounding of Separately grounded transformers in one building
- Thread starter nomad713
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Yes, you are required per article 250.104 (D)3. The structual steel and exposed metal piping would be required to have a bonding jumper installed to the common GEC.
Rick
How about the exception for 250.104 (D)3. All the water piping in this building is made from copper and already bonded at the first 5 ft of its entrance in the building to the main service entrance grounding bar. Also, all the strucutral steel and the re-bars are bonded to the main service entrance grounding system. Do I still need to bond the water lines in the area, on the 3rd floor to the common GEC?
The rule in 250.104(D)3 and the exception are a little tricky to read. Others can correct me if i say this wrong. The rule is to bond the "water and steel to the common GEC in each area the SDS serves". The exception allows us not to install an additional bonding jumper from the "SDS to the water and steel" if this jumper from the common GEC to the water and steel is already made in each area. So yes, a bonding jumper is required on the 3rd floor from the common GEC to the water and steel.
Rick
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