The electrical service wire lugs are the part of the electrical service panel that--if touched--will almost certainly result in serious injury or death.
Note in the accompanying photos the two black heavy-gauge wires coming into the panel from the top of the box. These are the ends of the service wires that come into your house from the outside.
Avoid touching these wires or anything that these wires touch.
While it's often easy enough to be cautious of the things your hands touch, be especially careful of things that you hold. The detached service panel, screwdrivers, wire cutters, wire snippers, pliers--these things can potentially touch parts of the service wires and transmit an electric shock to you.

