Bruce, right now, if you are too scared, just prod him with a wooden or plastic net/stick etc to discharge his electricity out of the main organ. Then you can touch him. But not advisable as most fish dont like being touched. he should also give you a small/tiny tingle at 3". Quite funny actually. At 1 foot, they will make you go. "Owww!," and you may shake your hand for a bit.
These have been known on regular occations to grow 6ft in the wild, but the biggest I have ever heard of in captivity is roughly 42". At an asian zoo. Hopefully yours doesnt exceed 18", incase someone has a weak heart...