I've recently found that the main water valve before the meter is
leaking, perhaps 1gal/week. I can see where the water is dripping out
from the valve where the handle goes into the fitting.

Our line comes up through a basement/closet floor -grounding wire -
valve - meter - valve - grounding wire - house. It appears to be
flare fitted copper.

I've been feeling brave as I just rerouted plumbing for our new
kitchen, but I don't want to bite off more than I can chew. I'm
wondering also if it was caused by something I did, perhaps tightening
down old gaskets too much.

Any suggestions or advice will be greatly appreciated!