peetey
Electrical
- Jan 10, 2005
- 42
I have asked a question similar to this one but I need definitive answers if I can get them. Imagine I have a pole with 3 transformers in a delta configuration
(secondaries) and it is a 480v ungrounded ct rated service. This only serves one customer that uses it for three phase power. It has a wye connected primary and the system neutral is tied to the pole ground and the transformer tanks are grounded but not tied to the secondary bushings. Essentially it is a straight forward bank. I would like to refer to three points on this service:
A. The power bank point (where it is normally grounded)
B. The current transformer point
C. The customers load wire (connected to load)
I have contemplated the idea of downstream grounding, meaning if I ground at a certain point it is only grounded from that point to the load. So If I ground one of the phases at the power bank, it is grounded from point A, B & C.
If I do not ground at the power bank but instead ground my meter can and then tie to the ungrounded B phase via the X2 wires (not single point grounded) I have established a ground at the current transformer point so it is grounded at point B & C but not at point A?
If I do not ground at the power bank, nor do I ground at the meter can, but the customer has chosen to ground one of the phases at the load. If he has grounded at point C only will the phase be grounded at point A & C?
If the service is 50 feet long and is grounded at exactly the 25' point I assume it will be grounded from that point to the load. Will it be or be considered grounded at 23'? If it is truly a downstream grounding principle if a customer establishes a ground at point C, what would prevent me from grounding another phase at point A?
If I have no grounded phase and choose to establish one how many amps will flow to ground to make the ungrounded phase go to ground reference?
Any other comments on this topic will be appreciated no matter who it comes from.
(secondaries) and it is a 480v ungrounded ct rated service. This only serves one customer that uses it for three phase power. It has a wye connected primary and the system neutral is tied to the pole ground and the transformer tanks are grounded but not tied to the secondary bushings. Essentially it is a straight forward bank. I would like to refer to three points on this service:
A. The power bank point (where it is normally grounded)
B. The current transformer point
C. The customers load wire (connected to load)
I have contemplated the idea of downstream grounding, meaning if I ground at a certain point it is only grounded from that point to the load. So If I ground one of the phases at the power bank, it is grounded from point A, B & C.
If I do not ground at the power bank but instead ground my meter can and then tie to the ungrounded B phase via the X2 wires (not single point grounded) I have established a ground at the current transformer point so it is grounded at point B & C but not at point A?
If I do not ground at the power bank, nor do I ground at the meter can, but the customer has chosen to ground one of the phases at the load. If he has grounded at point C only will the phase be grounded at point A & C?
If the service is 50 feet long and is grounded at exactly the 25' point I assume it will be grounded from that point to the load. Will it be or be considered grounded at 23'? If it is truly a downstream grounding principle if a customer establishes a ground at point C, what would prevent me from grounding another phase at point A?
If I have no grounded phase and choose to establish one how many amps will flow to ground to make the ungrounded phase go to ground reference?
Any other comments on this topic will be appreciated no matter who it comes from.