An electrical question

There has been much discussion of properly making connections to electric sub panels in places like barns and workshops. I have two very similar electrical situations, one in my workshop and one at our two way radio site. Both installations are from the 1950"s and feature no grounding conductor to the remote loads, only the grounded neutral and a hot. The line to the workshop is about 60 feet direct burial, through a landscaped area, and the one at the radio site is about 150 yards on poles with bare Copperweld wire.

The goal is safety and radio frequency noise suppression. The VFD on my lathe causes all sorts or RF noise since the case is not grounded. At the radio site, the tower and all incoming cables are grounded by several ground rods for noise an lightning protection, thus all cabinets are grounded through the antenna cables, but the neutral is not at this ground potential.

Thinking about the commercial radio sites I have worked at with a generator and service drop on a separate building, there gets to be an interconnection between the lightning/RF ground and safety ground. This is through the antenna cables going to the equipment and through the grounded plugs to the AC outlet or metal conduit to power supplies. This is probably not the best thing, but is shows a common situation where two separate ground systems end up tied together.

Is there anything short of adding a ground wire from the main panel to the remote loads? I am interested in all answers... Practical, theoretical, and code related.

Thanks!!!
Josh

The radio site should be easy, a grounded conductor on poles does not need to be ten feet above ground, even though I would rather see it on top as a static line if possible. Shouldn't be hard or expensive.

Your shop should have a ground and 60' isn't much, I'd change the feed. Other than that you cloud install a transformer allowing you to ground the secondary....

Well, the best step here is to ask a local electrician since he should familiar with local codes. Unless there is over current protection (fuses or breakers) before these panels they are not considered sub panels. If they are not sub panels then the neutral and ground are bonded at the panel with a driven ground rod or grounding plate. If these panels are sub panels then it is grandfathered in but you may see better conditions for the radio if there is a separate ground. Boring a new feed under the landscaped area may be an option. The overhead is an easy fix by adding a wire or converting to triplex.

At our facility when we were concerned with spikes, surges, transients and suppression what I did was run a separate dedicated individual Equipment GroundING Conductor to all the critical loads with its ground direct and all the way back to the panels Ground Buss versus a common ground wire out to all the loads on a branch circuit. Each critical sensitive load had its own Hot, a Neutral and an Equipment GroundING Conductor.

John T

For the shop, if I understand right, the receptacles are only 2 wire, no safety ground. If so you could just change the first outlet in each circuit to a GFCI one. Better yet if it's a ways from the panel, add a new one at/near the panel and then hook the existing circuit to it making it the first outlet.

Dusty

(quoted from post at 16:27:22 06/04/14) At our facility when we were concerned with spikes, surges, transients and suppression what I did was run a separate dedicated individual Equipment GroundING Conductor to all the critical loads with its ground direct and all the way back to the panels Ground Buss versus a common ground wire out to all the loads on a branch circuit. Each critical sensitive load had its own Hot, a Neutral and an Equipment GroundING Conductor.

John T

Click to expand...

John, are you comming to the Blue Grass Festal at Charlotte, MI. June 19-21 ?

Dusty