I install a momentary contact (push-button) switch in series with the resistor & indicator light. This ensures NO leakage current, BUT I have to "push to test" (when first plugged in).
I normally test the shore power, prior to plugging in, using the Receptacle Tester & Adapter, pictured at:
https://www.cruisersforum.com/photopost//showphoto.php?photo=1720&password=&sort=1&thecat=5 00

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Gord May "If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"