Both metal and AC scanning features on our tools have interactive calibration, which means you can customize the sensitivity of the tool depending on how difficult your target is to locate. If the target is deep within the wall, you want to calibrate the tool to make it as sensitive as possible so it will successfully find it. However, if the target is larger or closer to the surface, the maximum sensitivity will return a huge target “zone” around the actual location, and you can follow the steps below to narrow the search and locate the object you’re looking for.
For maximum sensitivity when searching for metal or AC, calibrate the tool in the air. Switch the tool to metal scanning or AC mode (depending which one you’re looking for), hold it away from the wall, turn the tool on and wait for the calibration to complete, and then put it against the wall and start scanning.
When you approach a metal object or live AC wire, the number of bars on the display will increase, and if the reading is particularly strong, there will be an audio tone and the SpotLite® Pointing System will light up. (Fig. 1) This does not necessarily mean you’re right over the target; if the tool is overly sensitive, it could detect the object from several inches away. Mark the point where you first got the strongest reading (indicated by the most bars on the screen or the tool’s alert system), then continue moving the tool across the wall in the same direction until the alert goes off or the bars diminish. Reverse direction until you get a strong reading or an alert again, and mark that second spot.
What you now have are two marks indicating the edges of a “zone” around your target. The metal or AC object is between the two marks, but if you want to get more precise, you can re-calibrate the tool to narrow down the location.
Place the tool on the wall, over one of the marks you made, and turn it on. (Fig. 2) Now the tool has calibrated closer to the metal object or AC wire, so it’s going to be more selective in scanning, and therefore more accurate about the location. Repeating the same steps from the first scan, move the tool across the wall towards the center of the “zone”, mark where the tool turns on the alert, keep moving the tool, and mark again where the alert goes off. You will now have a second, smaller target zone, with the metal object or AC wire in the middle. (Fig. 3)
You can repeat the steps above as many times as you’d like to narrow down the location. The closer the tool is calibrated to a metal or AC object, the more selective (more accurate) it will be in finding it.