Saturday, March 19, 2005

In-shack Ground System

The grounding project is coming along. We now have all the radio gear, computers, and internet devices protected against a Single Point Ground, which is a bus plate on the wall of the shack. For now, the SPG is referenced only to a waterpipe (hydronic, at that) ground that is good at 60 Hz, but not for fast surges. The SPG also ties back to the house AC ground through a green wire connection to a power wall-plate, but this is not much protection.

Here is some construction information. Maybe it will help others who are contemplating a similar project.

The SPG plate will attach to the shack wall, right over the existing panelboard. A backing of 3/4 inch plywood will sit behind the copper panel.

Wall attachmentBack panel

The SPG panel itself, after lots of work.

SPG panel

Here are a few details. The custom cut copper sheet is 15" x 20" x .0647" Copper 110 = 16 ga. or 48 oz, supplied by They provide great service. You can see a number of 1/4-20 wingnut connections for miscellaneous ground strap connections. There is also a clamp for 1.5" copper strap, for eventual connection to a new external earth connection. The Polyphaser PLDO and ICE 348 devices are described in earlier posts below. The Hyperlink DSL protection is also visible, along with a number of PolyPhaser coax surge devices. Various antenna switches surround the panel, but are not part of the grounding system.

Tabletop Ground Bus

Using another copper sheet, 6" x 48" x .0647", we constructed a tabletop "ground distribution system" to provide a well-defined reference for the radio desk.

wide shot of table

detail shot of table

One connection bonds the ground bus to the metal office desk. Another connection goes a couple of feet across to the SPG plate on the wall. One-inch tinned braid is convenient for these connections.

1 comment:

Unknown said...

Martin, thks for sharing! About your SPGP and similar: I fear flashover between incoming and protected cables. So I bought a LARGE outdoor metal junction box, mounted on outside wall inches from perimeter ground, and bulkhead-mounted my coax protectors (ICE) on the sides. COMCAST 3-play coax comes down EMT thru box straight to ICE 312(1.5-1000 MHz): yes, I too looked at U-Verse upgrade option, imagined what you experienced, and hung ATT's line on the pole across the street! -Tom, KG6RRU