15-08-2019, 10:48 PM
A good summary of the Australian situation in respect of live chassis TV receivers was provided in an article in Electronics Australia magazine for 1975 August.
EA 197508 p.64.pdf (Size: 687.74 KB / Downloads: 4)
The key issue was erosion of metal pipework and other structures by parasitic DC flowing via the earth path. Evidently by 1975, much of Australia’s supply system was of the MEN (multiple earthed neutral) type, and measured DC via the earth path was quite high. Hence the avoidance of appliances that fed DC back to the supply system.
The same arguments would have applied in New Zealand, although I have yet to find hard documentation. Virtually all supply systems in NZ are MEN, which has been the national standard since 1920.
Regarding US practice in respect of the loading of split-phase household supplies, at least basis the house I had built in Texas back in 1990, the lighting and receptacle loads were approximately split between the two phases. A 240-volt outlet was provided in the laundry room for the dryer, and another in the kitchen for the oven. I am not sure if the island cooktop also used 240 volts, as the wiring was plumbed-in. The distribution system was evidently multiple grounded neutral, and the neutral was bonded to ground and the ground rod at the switchbox. The incoming telephone and cable TV services were also grounded to the main ground rod where they entered the house. In fact, grounding rules were quite strict. The structures of outdoor antennas had to be grounded, as did the outer screen of coaxial feeders, such grounds either returned to the main ground rod or if using separate rods, the latter had to be bonded back to the main ground rod.
Cheers,
Steve
EA 197508 p.64.pdf (Size: 687.74 KB / Downloads: 4)
The key issue was erosion of metal pipework and other structures by parasitic DC flowing via the earth path. Evidently by 1975, much of Australia’s supply system was of the MEN (multiple earthed neutral) type, and measured DC via the earth path was quite high. Hence the avoidance of appliances that fed DC back to the supply system.
The same arguments would have applied in New Zealand, although I have yet to find hard documentation. Virtually all supply systems in NZ are MEN, which has been the national standard since 1920.
Regarding US practice in respect of the loading of split-phase household supplies, at least basis the house I had built in Texas back in 1990, the lighting and receptacle loads were approximately split between the two phases. A 240-volt outlet was provided in the laundry room for the dryer, and another in the kitchen for the oven. I am not sure if the island cooktop also used 240 volts, as the wiring was plumbed-in. The distribution system was evidently multiple grounded neutral, and the neutral was bonded to ground and the ground rod at the switchbox. The incoming telephone and cable TV services were also grounded to the main ground rod where they entered the house. In fact, grounding rules were quite strict. The structures of outdoor antennas had to be grounded, as did the outer screen of coaxial feeders, such grounds either returned to the main ground rod or if using separate rods, the latter had to be bonded back to the main ground rod.
Cheers,
Steve
