An AC powered device detecting the presence of a conducting fluid using a source of detecting current through the fluid other than a grounded supply. Percutaneous procedures can be used to occlude and obliterate the greater saphenous vein, for example in the treatment of varicose vein condition caused by venous reflux. Thus, engine oil can be reliably returned to the oil pan from the cylinder head of the engine even when the vehicle is experiencing high acceleration in a direction that tends to cause backflow of the oil through the engine oil return system.