From way back in the day--Meter wiring. Top row three 0-30 range VAC meters wired "across the line" (parallel) with power jumpered up from the amp meters below and connected to the common white separately.
The AAC units below, 0-15 range, are connected "in-line"( series) with heavy enough color-coded wire to read/carry the full 10 amp load of the particular power district being monitored.
Meters are Der 670 units assembled in Taiwan of Japanese components and were distributed by a New Zealand Electronics Company. Cost about $12 each + air fare from multiple destinations . Analog meters, much less Digital, in the desired range were not easy to find in the early days of the Forum.
Photos are very old-1997 layout under construction.
