Real life experience ... I have all of the exterior lighting around my screen cage on a single GFCI circuit. It trips a lot and I never find a single box or fitting that is leaking enough to show up on a meter but the combined leakage from all of them trips the GFCI. I still like the idea of GFCI enough to keep it but I may split up the circuit
I can't imagine the combined leakage of a whole service being under 5ma or even 30ma.
