Pump had a crack and electrocuted me :-((

[RominK]

So, I was doing a water change yesterday and when I plugged everything back on, my chiller pump wasn't working. Felt a little tingling feeling in my fingers as I took it out of the sump area of my 29 G biocube. When I took it out to take a closer look at, I saw a crack in the case housing, under the cover plate. Good news is, from what I've seen, my two Acan colonies are very closed for the past few days, and that's the only livestock affected so far (as far as I can see).
I need to know from you experts out there, how do you monitor if there is any current in the tank?
Appreciate your feed-back !
Happy Monday to you all.
Romin