Surface-Mount Electrical Box and Conduit Layout
Installing electrical boxes plumb and level, and carefully laying out and measuring bend locations for conduit, makes for clean installations.
When installing surface-mounted Electrical Metallic Tubing—a type of conduit—you want things to look neat. California electrician CJ Nielsen has some tips to make that happen.
First, use painter’s tape to lay out all box and bend locations. You can make any marks you need to on the tape to avoid marking up the wall. It aids in visualizing the layout, and also makes it easy to adjust or move the layout—just move the tape.
To aid in mounting new electrical boxes, dry-fit boxes to the wall, and use magnetic torpedo levels to help get them plumb and level. Mark through the fastener holes in the back of the box so you know where to drill for hollow-wall anchors.
After the holes for the hollow-wall anchors are drilled, you can remove the tape and mount the box.
To lay out bend locations, simply mark level and plumb lines over and up or down from the box knockouts you’re going to use. Most boxes have multiple knockouts that you can remove to install conduit fittings, which hold the conduit to the boxes. Again, start by putting tape in the general location of the bends before marking level and plumb lines. Where the lines intersect is the location of the back of your conduit bend.
Measure from these intersecting lines to the box knockouts. These are the measurements you’ll use to make your bends.
For even more information, check out this feature article, Crash Course in Conduit, in FHB #273.