Professional electricians use a variety of testers to check a wide range of electrical functions in residential and commercial electrical wiring, and DIY homeowners will also find some of these tools useful. Learning to identify these testers, understanding their functions, and learning how to use them will greatly expand your expertise when it comes to working on electrical wiring.
Some testers are multi-function devices that can perform most, if not all, of the common electrical testing duties, while others are single-function devices that test for a single function. Various electrical testers can be used to check voltage levels in both AC and DC circuits, to test for amperage, continuity, short circuits and open circuits, polarity, and more.
Some of these terms are unfamiliar to most homeowners, but most important for a DIYer who plans to work on home wiring is knowing how to test for the presence of live voltage. Several of the devices described below fulfill that function.
Source: The Spruce