PR-90 / PR100-LAB Application Information

The PR-90 may not install properly in some older (20++ years) wattmeters. This is due to variation in meter stud spacing, meter stud position, and meter / side location tolerances.
To check your meter for compatibility, remove the back cover, and measure the center to center distance of the meter studs. The acceptable range is 1.45 to 1.55 inches (36.8 to 39.3mm). (see diagram)
Next, check the meter stud postion relative to the side opening holes. From the bottom edge of the studs to the top of the side opening, there should be 1.1 to 1.2 inches (27.9 to 30.4 mm). (see diagram)
If the measurements of stud spacing and stud position are not within the listed range, the
PR-90 board will not install without user inovation. Some users report of using “Z” bend
adapters, or ring lugs as an adapter. Another option is to use the PR-80 universal board,
and mount it using the four mounting holes, and wire it in as shown in the instructions.
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