According to NEC® 250.114(4)(g) Exception, which of the following can be used in lieu of grounding for portable tools in non-residential occupancies?

The correct answer is that isolation transformers can be used in lieu of grounding for portable tools in non-residential occupancies, according to NEC® 250.114(4)(g) Exception.

Isolation transformers serve an important safety purpose by providing a means of reducing the likelihood of electrical shock from portable tools. They achieve this by electrically isolating the tool from the supply voltage while still allowing it to function properly. This isolation prevents fault currents from traveling back to the tool chassis, thereby minimizing the risk of electric shock to users.

The context of the other options highlights different methods of electrical safety that are not specifically recognized by this NEC exception to substitute for grounding. Double insulation is a design feature in tools that adds an extra layer of insulation between the user and live parts but is not indicated as an alternative to grounding in this scenario. Metallic shielding offers physical protection but does not fulfill the grounding requirement. Drain wires are typically used for providing a low-resistance path to ground in shielded cables, but they do not fulfill the grounding alternative for portable tools specified in NEC 250.114.