Okay so ZonePlus is perfect for this.
You make a zone with your cylinder part
local safeZone = Zone.new(cylinder)
safeZone.localPlayerEntered:Connect(function()
-- lightning off
end)
safeZone.localPlayerExited:Connect(function()
-- lighting on
end)
-- Check first time
if zone:findLocalPlayer() then
-- lighting off
else
-- lightning on
end