Copper is way more conductive than a human body, you are correct. So yes, when lightning strikes a grounded copper rod, most of that raw voltage will take the easier path, which is straight down the metal into the earth. But lightning isn’t a tidy, single-lane current. It’s a chaotic, high-energy burst that doesn’t strictly obey “least resistive path” rules. If you’re holding that rod, uninsulated, with your feet on the ground, you’re now part of the grounding system. Some of that current will branch through you, because your body offers a parallel path to ground.
Even a small fraction of a lightning bolt (we’re talking tens of thousands of amps) is enough to stop your heart, burn your skin from the inside out, or fry your nervous system. Holding a grounded lightning rod during a strike is basically volunteering to be a secondary lightning conductor.
And to estimate how much current flows through you, you’d model it like a parallel circuit. one path through the copper rod (very low resistance), one through your body (much higher resistance, but not infinite). Say the rod has ~ 0.001 ohms of resistance and your body ~ 1,000 ohms, almost all current flows through the rod. But with a lightning strike pushing up to 100,000 amps, even 0.01% through you is 10 amps — more than enough to kill.
The exact split depends on contact resistance, moisture, and how well you’re grounded, but in lightning physics, “a little” (over 0.1 A) is lethal.
