Tool Sheath

Tool Sheath
Electrical: Power Supply to Dishwasher has no ground wire?

I am replacing my dishwasher. The dishwasher power supply, between the box under the counter and the dishwasher, is within a flexible armored sheath. When I disconnected the power from the old dishwasher, I noticed that there was no ground wire. Before I go to the hardware store, I thought I'd ask if anyone knew if I can just buy the correct dishwasher power supply with three wires, connect in the existing box under the cabinet and move on or if this is a more serious complication. When done, I want the installation to be safe, with the three expected wires though the sheath all the way to the dishwasher.

For what it is worth, I have the knowledge and tools to safely replace dimmer switches, etc., but I don't do anything "behind the walls". If this can be done at the box under the sink, I am in business.

The armored cable (sheath) is the ground.

The Real Avid Turkey Tool and Toter Sheath (Short Version)