For the chemistry experiment what safety precautions are required, because I can't think of any.
Is 'electric current' a precaution?
There isn't a lot of safety precautions for the chemistry experiment. In the actual experiment, you may say you need to handle the metal nails carefully as it can cause an injury. You can also make sure the voltmeter (I recommend using an analog voltmeter) is safe to use. You may also mention that you have to wear gloves, goggles and a labcoat. It's quite a safe experiment comparing to the other mandatory chemistry experiments in any JC Science book.
Also, 'electric current' is not a precaution (because a precaution is an action done in advance to avoid problems or danger). However, it is something you have to take caution with.