The effect it has on the human body isn't the same as electricity out of your wall socket, for sure. If Luke was getting shocked in Return of the Jedi by 60 Hz AC he wouldn't have been able to form a coherent sentence asking his father for help. His muscles would have been contracting beyond his ability to control his diaphragm.
If force lightning is still electricity, we can narrow down the details, at least. We're talking about a flow of charge carrying particles through the air and through the body of the target. But where is that charge coming from and going?
Is it flowing in a circuit, leaving the user and returning to him as in a DC circuit? If so, why don't we observe a return path? Is it flowing through the floor? If so, why is it not damaged? Or perhaps it's in one finger and out the other?
More likely it's AC, with no net flow of charge out of the user over time. The user must be one pole of an AC voltage source, with the other pole somewhere behind or inside the target. But then, if the user can manifest arbitrarily located voltage sources outside of their body, why does the other apparently have to be in his fingertips? Palpatine contemplates in one novelization how Vader's artificial arms prevent his use of force lightning. But maybe only one node has to be in the biological body of the user, and Vader's real limitation was the possibility of damage to his suit.
If this is the case, could lightning be harnessed for productive purposes? Use it to actually power electrical equipment? If so, how many watts worth? Can we know the horsepower of the Dark Side?
Or is charge permanently leaving the body of the user and building up as static elsewhere? That would mean the user and some other object are gaining net charge of opposite polarities. This would not normally be physically sustainable, creating a tremendous electrical field and voltage potential. The Emperor would essentially be one plate of a giant capacitor, with the dielectric being the Force itself. The mother of all static discharges will happen as soon as the user is not actively trying to prevent it. Maybe this is why the emperor violently exploded?
Or is the user summoning charge from nothing and returning it to nothing? Conservation of charge is one of the fundamental physical laws of the universe. If defying that was a possibility, the user of force lightning would have the ability to rewrite the very structure of any matter. I may not know the power of the dark side, but I think we can be sure that if the emperor could do that, we would have very different movies.
So if force lightning is electricity, based on Luke's ability to still speak, I think it must be AC of either very high or very low frequency. High frequency would tend to travel over Luke's skin rather than penetrate his body. But then, perhaps the Emperor manifested the remote voltage node inside Luke's body.
Perhaps I'm thinking about it wrong still. The sound of the lightning wasn't a single tone, but was a pretty broad frequency profile. I'm honestly not sure what that would do to a human body, but it's at least possible you'd still be able to speak. I still think the fundamental would have to be pretty high, perhaps in the low kilohertz... Has anyone done a Fourier transform of the sound of force lightning?