I will reinforce the folks who say the coil is a bad idea.
It slows the leading edge of the spike and while that is happening it can go the other way.
In surge protection we do exactly the opposite. We put inductors (ferrite beads) in the signal lines and very short, straight grounding conductors. The theory is, by the time the shot could get down the signal lines, the ground has shunted it out. I know one engineer who swore tying a few overhand knots in the power cord would mitigate a transient. A lot of people told him he was nuts but if you looked later they had a few knots in their power cords. A ferrite bead is a lot better.
