Never work on live electric circuits or electric service panels. Remove circuit breakers by moving the switch handle to the OFF position and pushing on the handle away from the middle of the panel. Strip outer sheathing on the cable, then insert the cable into the box through one of the knock-out openings. First, connect the ground green wire, followed by the neutral white wire. Update the panel directory to reflect the addition of the new circuit breaker and new positions of old circuit breaker if any needed to be moved. They should be marked on the mountings.
Place the blade of a screwdriver at the inside-most ring and strike sharply with pliers or hammer.
How to Connect the Power Cord for an Electric Range
Install a strain-relief clamp to secure the cord to the back of the range. Its purpose is to grip the cord so that the wire connections can't come loose accidentally. However, you must configure the range wiring so the case ground is tied to the neutral terminal. Strip the outer jacket.