ken44
Senior Member
- Location
- Austin, TX
I need some input from the community on the following matter:
A contractor recently install an outdoor pad mounted transformer with a 12,500 volt primary (3 phase, 4 wire) and a 480 volt secondary (3 phase, 5 wire), all of the conductors are in PVC which is encased in concrete. I discovered that while they connected the primary grounds, they failed to connect any of the grounds on the secondary side to anything-they are just taped up and laying inside the transformer, and when I called them out on the matter, they stated that the following in an email:
"The grounding conductors were called for on the drawings but they are not required. We feel they should be neatly coiled up and placed inside each enclosure and not be connected. Connecting these wires could potentially create a parallel path to ground. The ground wires could be pulled out however we feel that this is an unnecessary disruption to the building and building tenants.
We feel the installation complies with NEC 2014 section 250.30 (a)(1), therefore a supply side bonding jumper is not required per the exception for section 250.30 (a)(2). This is typical for pad mount transformer installations.
We do not recommend connecting these ground wires to the electrical distribution system.
I have attached a simple diagram showing how the installation complies with code.
I am available to discuss this issue in more detail if needed."
A contractor recently install an outdoor pad mounted transformer with a 12,500 volt primary (3 phase, 4 wire) and a 480 volt secondary (3 phase, 5 wire), all of the conductors are in PVC which is encased in concrete. I discovered that while they connected the primary grounds, they failed to connect any of the grounds on the secondary side to anything-they are just taped up and laying inside the transformer, and when I called them out on the matter, they stated that the following in an email:
"The grounding conductors were called for on the drawings but they are not required. We feel they should be neatly coiled up and placed inside each enclosure and not be connected. Connecting these wires could potentially create a parallel path to ground. The ground wires could be pulled out however we feel that this is an unnecessary disruption to the building and building tenants.
We feel the installation complies with NEC 2014 section 250.30 (a)(1), therefore a supply side bonding jumper is not required per the exception for section 250.30 (a)(2). This is typical for pad mount transformer installations.
We do not recommend connecting these ground wires to the electrical distribution system.
I have attached a simple diagram showing how the installation complies with code.
I am available to discuss this issue in more detail if needed."