Re: Zapp for 1-2 hours ?

On the Dr. Clark Research Association website, there is a recommendation in cancer prevention 3 week protocol to zap 6-8 hours per day in plate zapping.

We often use a set of frequencies from 36 minutes straight, for example, at 2-6 minutes, or even 22 minutes per frequency up to 6 hours or more, depending on the protocol/treatment used http://www.frequencyresearch.org

In short, there IS no limit, though some will want to watch for herxemier reactions, skin reactions (move the electrodes or tens pads, etc. if that becomes an issue or back off in your use some, etc.), etc. The Terminator, for example, can be and is worn by many for 24 hours a day for 3 weeks to 3 months at a time, etc. etc.
If you are using a low power battery operated zapper, you probably don't have much to worry about anyway... however, if you are using a high power frequency generator, frequencies in the LOW ranges used for very long CAN cause burns, particularly if you place the electrodes or tens pads on thin areas of skin.