This does not guarantee against shock in the even of frayed wiring or damage to the tool. Metal casing also can be lined with nonconductive material. Always calculate the existing and potential load of a circuit before you add on to it. The more carefully you plan your work and routing for circuits around finished walls and ceilings, the few repairs you'll have to do later. A panelboard directory, or circuit directory , is the formal name for your list of circuits.
Every electrician makes a directory when installing a service panel.