Warning: Do not perform this modification while the cable is connected to power. For your safety the cable needs to be unplugged.
Next, I connected the exposed ends of the extension cord the the removable relay block on the back of the Nerve Center. You'll find three connections for each block with can be used depending on the result you want. For our purposes, we wired one cable to the connection marked COM, and the other to the connection marked NO (Normally Open).