Just had a read through this,
Voltage in the aquarium it was at the bottom of the page that Wildechild posted.
Something I found very interesting (as my head almost exploded from technicalities) was the part about bizarre powerhead measurements half way down the page. The plastic housing of his powerhead induces voltage, this has nothing to from what I can tell that there's anything physically or visually wrong with pump or wiring (well maybe internally) but nothing noted. It appears to be the same phenomenon that has been taking place with all my equipment. Sure, I can check the new'ish skimmer for signs of issues, but highly doubt I will find anything visibly wrong, therefore the pump of the skimmer is now leaking voltage by way of "some cause".
Find the answer and I'll call you genius! Or a good Googler