Brian Way
Brian Way
Brian Way

The DCT419 is an affordable scanner capable of detecting and distinguishing between various items found in walls. It can find wood (studs and blocking), non-ferrous metals (such as copper pipes, aluminum, and de-energized wire), plastic (such as PVC, electrical boxes and low voltage wire) and ferrous metals (such as steel studs, cast pipes, nail plates & screws). It can also determine whether or not the wire it finds is live.

Tools of the Trade wanted to test the new scanner so they came to me, because my company specializes in the installation of millwork and cabinets. We do a lot of work in hospitals and commercial environments where there are more than the usual number of things you don’t want to hit hidden in walls. Over the years we’ve installed thousands of cabinets, and during that time we’ve hit our share of water lines and one C02 line I know of.

The tool arrived at the beginning of February and we’ve been using it for over a month. The DCT419 will scan up to 9.8 feet across a wall through drywall, plywood, OSB, tile, and even concrete—to a maximum depth of 3 inches. I’ve had success using to scan through a combination of surfaces such drywall/plywood, tile/plywood, tile/drywall, and wood lath plaster.

This was actually my second time testing a DeWalt scanner. The first was with an earlier model (DCT418) that was pulled when this model (DCT419) came out at the beginning of 2015. They look like the same tool but they’re not. The hardware is more or less the same but the new model has a better software interface, is more user-friendly, and does a much better job distinguishing between materials.

The DCT419 works well but it’s important to understand it’s not like Superman’s X-ray vision; it doesn’t allow you to see through the wall. It tells you the type of materials hidden inside a wall, and it’s up to you based on your experience and what you know of the wall to decide what those materials are. The scanner might tell you there’s ferrous metal behind the drywall; you have to decide if it’s a nail or screw, electrical conduit, black pipe, or something else. Ditto for plastic—which could be a drain pipe, Romex, PEX pipe, or something else made from plastic.

Scanning the wall is a matter of completing the following steps:

The scanner is showing wood behind this tile backsplash—almost certainly a stud. It will show double studs if that’s what’s there.
The scanner is showing wood behind this tile backsplash—almost certainly a stud. It will show double studs if that’s what’s there.
The scanner senses the presence of wood and some magnetic material—most likely a stud with a nail in it. Move the scanner up or down a couple of inches and the magnet icon (the U for horseshoe shaped magnet) will probably go away.
The scanner senses the presence of wood and some magnetic material—most likely a stud with a nail in it. Move the scanner up or down a couple of inches and the magnet icon (the U for horseshoe shaped magnet) will probably go away.

Turn the scanner on and set it to the construction type: wood stud, steel stud, or concrete. Setting the tool to these types does not limit you to scanning those materials; it just allows for a more accurate pre-map scan.

Pre-scan by sliding the unit across the wall in one direction (without lifting it off the surface). The scanner will let you know if you go too fast or slow. During the pre-scan the computer “figures out” what’s wall, what’s wall with something behind it, and what that something is.

At the end of the pre-scan reverse direction and slide the unit (it rolls on wheels) back across the wall. As you move the unit, graphical images representing the material behind the wall at that location will appear on the color LCD screen. It’s important to perform multiple scans at different heights because we’ve all encountered pipes, wires, and ductwork that does not run the full height of the wall. You may miss these items if you only scan at one elevation.

Pros:
-The storage case is fantastic. As usual, a highly durable DeWalt case made to withstand all jobsite conditions.
-The DCT419S1 is an all-inclusive kit. It comes with the scanner, the case, battery and charger. Even if you don’t own other DeWalt tools with a DCB120 12 volt battery, it is all included at a retail price of $399.
-Extremely comfortable and ergonomic 1 handed use.
-It’s a money-saver; miss one pipe or wire you might otherwise have hit and you’ve saved the price of the tool.

Cons:
-The minimum assumed spacing between materials is 4 inches. For example, if there’s a metal duct in the bay of a wood stud wall the scanner only picks up the ferrous duct work. It misses the studs because the need to “avoid” hitting metal “takes priority” over detecting wood. It’s how the algorithms are set in the software; 4 inches seems to be the industry standard.

The scanner is showing plastic—which I happen to know is a drain pipe. But icon would be the same for any type of plastic, including low-voltage wire or Romex that is not live. The lightning bolt icon is lit, so there is also voltage present in the area.
The scanner is showing plastic—which I happen to know is a drain pipe. But icon would be the same for any type of plastic, including low-voltage wire or Romex that is not live. The lightning bolt icon is lit, so there is also voltage present in the area.
The scanner is showing non-ferrous metal, which I happen to know is a 1/2-inch copper pipe. But it could also be some other non-ferrous metal. It doesn’t normally detect shielded copper (inside Romex or conduit) but will if the wire is thick enough—like a very heavy cable.
The scanner is showing non-ferrous metal, which I happen to know is a 1/2-inch copper pipe. But it could also be some other non-ferrous metal. It doesn’t normally detect shielded copper (inside Romex or conduit) but will if the wire is thick enough—like a very heavy cable.

-The lightning bolt icon changes from gray to yellow when it senses electricity. I’m usually so focused on reading the main part of the

screen that it’s easy to miss seeing the change in the change in the electric symbol. It would help if the unit were to emit an audible sound when electricity is present (as laser detectors do when they are close to a laser level’s beam).
-The device is not 100% accurate all of the time; it’s a computer and there are occasional glitches. This is why it’s important to take multiple readings at different heights, and both vertically and horizontally across the wall. Do this and the odds are in favor of your finding everything that’s in the wall.

Bottom Line
The DCT419 does exactly what it’s supposed to do. I’ve used scanners that are 2-3 times the price of this one, and while their capabilities may be greater, they’re too complicated—requiring you to memorize a bunch of codes or pull out the manual to decipher them. I like how easy it is to use the DeWalt scanner: You can almost open the box, turn it on, and start using it. If you’re one of those people who can’t bring himself to study the owner’s manual, you could probably get by with a quick read of the overview pamphlet. It will detect wood, ferrous and non-ferrous metal, plastic, and electrical current. For me, it’s worth having this tool just to avoid hitting non-ferrous metal, such as the copper water pipes and gas lines hidden in the walls of the buildings where we install cabinets. If we miss one we might otherwise have hit, the tool is paid for.

For those of you who are interested in some of the geekier details of the detector, I took one apart, photographed it, and wrote a story about what I found.

DeWalt DCT419S1 Scanner Specs
Power source: 12V MAX battery
Display: 3.5-inch color LCD; 320 x 240 resolution
Scanning range: up to 9.8 feet across the wall
Wall surfaces scanned through: drywall, plywood, concrete, and ceramic tile
Embedded materials detected: wood, ferrous metal, non-ferrous metal, plastic, and unshielded live electric
Maximum sensing depth: 1.5 inches (wood); 3 inches (ferrous metal, non-ferrous metal, plastic, unshielded live electric)
Minimum assumed spacing between embedded material: 4 inches
Positional accuracy: +/- 1/2 inch
Languages: English, Spanish, French
Country of origin: Built in the USA with Global Materials
Includes: DCT419 scanner, one 12V MAX battery, charger, kit box
Street price: $400-$490