Would any harm be done if toddler chewed on copper wire that wasn't attached to electricity ? i' m not positive it happened. just found one in garage.

Depends : Vast majority of swallowed objects pass through the gastrointestinal tract without problem.Elongated sharp objects, {needles, eating utensils, bobby pins, or razor blades}more likely to lodge at areas of narrowing or impinge at regions of anatomic angulation. A lot depends on configuration and size of wire. Most opaque foreign bodies apparent on radiograph.Some removed by surgery or endoscopy.

Copper: Copper is necessary for blood cell production and wound repair. They even put it in vitamins! too much can be neurotoxic, but it's unlikely he could consume much by chewing on a wire.

The wire...: , itself is probably harmless, but that the question came up is a marker for hazardous objects (of which a garage is usually full) are accessible to a child. The best thing to do right now is to keep the toddler out of places such objects are kept in.