Would 3 negative 20 minute routine eeg rule out epilepsy?

Once you get to 3 you would have little to support the epilepsy label. However, seizures are sometimes subtle and a video EEG done in sleep/wake states may be used to catch events that may be elusive. The basic fact is you can have an abnormal EEG and not have epilepsy & you might have a normal EEG & still have events. The doc with all the information is in the best position to decide on a label.

Diagnosis of epilepsy is a clinical conclusion supported often, but not always, by an abnormal EEG. 3, 20 minute EEG's confirm little if anything, and do not capture variations in cerebral activity in most cases. Ambulatory studies over 72-96 hrs are far more accurate, and inpatient video studies are the "gold standard". Suggest you seek second opinion.