- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
This is a spin-off from another thread ( here ). I didn't want to confuse that discussion by bringing up an issue on a separate installation.
I am designing a new ?light industrial? facility that will be about 160 x 250 feet. It will have electric rooms in three of the four corners. Each electric room, including the main, will have an SDS (i.e., transformer to step-down from 480 to 120/208).
My original plan was to bury a ground ring around the building, with ground rods ?every so often,? and with the Main Panel?s GEC and the GEC for each SDS connected to this ring in two places. I think this is an adequate Grounding Electrode System, though I admit it may be overkill. What I am being told by a reviewer is that it is absolutely overkill. So what is my best options for ?down-sizing??
There is no ?building steel,? as it is a single story building with ?tilt-up? concrete walls. Water enters the building at one place, and the point of entry of the pipes is at least 40 feet from the nearest electric room (and is much farther from the other two electric rooms). The entire length of water pipes is not exposed, so using them as a Grounding Electrode is not an option.
My questions:
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I am designing a new ?light industrial? facility that will be about 160 x 250 feet. It will have electric rooms in three of the four corners. Each electric room, including the main, will have an SDS (i.e., transformer to step-down from 480 to 120/208).
My original plan was to bury a ground ring around the building, with ground rods ?every so often,? and with the Main Panel?s GEC and the GEC for each SDS connected to this ring in two places. I think this is an adequate Grounding Electrode System, though I admit it may be overkill. What I am being told by a reviewer is that it is absolutely overkill. So what is my best options for ?down-sizing??
There is no ?building steel,? as it is a single story building with ?tilt-up? concrete walls. Water enters the building at one place, and the point of entry of the pipes is at least 40 feet from the nearest electric room (and is much farther from the other two electric rooms). The entire length of water pipes is not exposed, so using them as a Grounding Electrode is not an option.
My questions:
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- <font size="2" face="Verdana, Helvetica, sans-serif">Can I just call for two ground rods outside each of the three electric rooms, and call it a day?</font>
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- <font size="2" face="Verdana, Helvetica, sans-serif">Do I also need to bond the ground bars in the three electric rooms to each other? That is, do the main and the SDSs need to share a common Grounding Electrode System?</font>
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- <font size="2" face="Verdana, Helvetica, sans-serif">Can I run bonding conductors overhead across the building, using bare copper inside pvc conduit (for physical protection)?</font>
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- <font size="2" face="Verdana, Helvetica, sans-serif">Is there a ?significant difference? (i.e., more than 25% difference) between the installation cost of my original plan (i.e., ground ring) and the installation cost of the ?down-sized plan??</font>