Whether you charge unattended (97014 or G0283 for Medicare) or attended electrical stimulation (97032) depends upon how you provide the modality.
If the therapist simply sets up the modality (i.e., places the electrodes, determines the treatment parameters, turns the machine on/off, removes the electrodes), but otherwise leaves the patient during the treatment, then it is an unattended (untimed) modality code. If, however, the therapist sets up the modality and using a probe or the electrodes, provides stimulation in conjunction with having a patient perform movement (muscle contractions, ROM, exercises, gait training, etc.), then the modality is now an attended modality and is coded based on the time performing the procedure.
For example, providing electrical stimulation during the swing through phase of gait training to assist the patient with dorsiflexion to clear the toe. Another example would be a patient who had been in a long leg cast and was receiving stimulation to the quadriceps while being asked to perform terminal knee extension exercises. These types of attended stimulation modalities are often used to assist patients with muscles that are weak or do not function properly such as following a stroke or incomplete spinal cord injury.