WARNING: Mild spoilers to follow, if you haven't seen tonight's Heroes.
I can't believe I'm actually going to discuss electrical theory in the same sentence as a show about superheroes, but goddamn it, people who write Heroes, electricity doesn't work like that!
Electricity, like all other forms of energy in the universe, flows from areas of greater concentration to areas of lesser concentration (or as electrical engineers say, from higher to lesser potential). You get electrocuted only when you complete the circuit between those two potentials, which is why birds don't get fried when they perch on power lines. It's also why rubber boots/gloves/mats keep you safe from electricity, because they insulate -- rubber doesn't conduct electricity, and therefore prevents a circuit from forming between voltage, you, and the ground.
So what HRG did to Elle tonight is completely wrong. Again, I know it's rather silly to discuss physics in a show about superheroes, but there are certain expectations of logic in a medium such as this. For example, if a hero had fire powers, you would expect that his power would not work if he were, say, immersed in water.* Likewise, since Elle has electrical powers, you would expect that her powers follow the basic rules of electrical current.
How's that, you ask? Excellent question, Voices in My Head! Allow me to explain!
As I stated above, you only get shocked if you are in the link between high and low potential. But since Elle generates electricity, she is high potential! It doesn't matter that she's been sprayed with water and her feet are in a tub, her electricity will not harm her for the same reason that water doesn't flow uphill and skittles make a mess on the floor when the bag breaks: the Second Law of Thermodynamics.
Interestingly enough, the basic effect -- neutralizing her power -- could be easily achieved by chaining her to a metal stake buried in the ground, because the volume of the planet has much lower electrical potential than, well, anything else on Earth, and is quite happy to absorb however many volts you care to throw at it. This is, in fact, how lightning rods work.
So I guess I'm incensed because it's both poor science and poor writing. Elle doesn't need to get shocked; the scene isn't supposed to convey great irony or poetic comeuppance. It's sole purpose is to say "Hey, I've neutralized your power; now you must do as I say." This entire mess could have been avoided if a writer somewhere had simply done his homework and not decided to get cute.
Now playing: Apoptygma Berzerk - Electricity
*Unless you gave some sort of handwaving explanation about how water is really only hydrogen and oxygen, both of which burn, and then proceeded to have the character engage in some really terrifying atomic-scale manipulation. Or possibly overheat his own body, boiling the water into its components. Either way, it will in all likelihood be very painful for said hero....