I think a good rule of thumb on installs is insist/bid in a new outlet/circuit installed on any c-9 job over $1500 and any other job over $2000, and then a double outlet on jobs over $3500. c-9's pull 7 watts, 250 of them is 1700 watts plus, and is around 1600 bucks for me. Those kind of watts need a dedicated circuit. we pay a local electrician 150-170 bucks for a double outlet double 20 amp load on an A/C line. If I think this customer is a landscape light potential, and they have 2 A/C units, I do 2 double outlets for around $250. when you have GFCI issues, many times you can move around plugs to a different GFCI and it won't pop. links pull about .2-.3 amps each, so 36 on a house is over 10 amp load. I sell them for 60, so when you hit $2000 you are getting close to the max load on an unknown circuit. mini's can add up amps quick. I have used 5000 to tightwrap ONE TREE. that is about 12-15 amps. That maxes a circuit, and I only charge about 1250 for that many. once you hit 2000 mini's, and anything up top, you need an outlet.