The only way to know for sure is to put the insulated probes/electrodes into the vessels/veins about 6 inches apart and measure the current and voltage directly! This will give a definite result in the current and voltage present. If both give readings, look for the 50 to 150 nanoAmps current flow. You don't want too much current and not to little. This will give the answer if the wrists or crossbody works and what level of current is present.