D = Distribution. Distribution or sub-distribution lines are lower in voltage, and are the final stage in the delivery of electricity to end users. They are part of a network that typically includes medium-voltage power lines, substations, pole-mounted transformers, low-voltage distribution wiring and meters. This is what you see in your neighborhoods (if you live in an older area with above ground lines).
Interesting! It is the REGULATED T&D that is costing us while ‘deregulated’ power generation costs are decreasing!
In the photo with the transformer, how much voltage is in that top side? 7680?