Install Instructions
Table Of Contents
AT120A, AT140A, AT150A, AT175A UNIVERSAL TRANSFORMERS
3 69-0251—04
Fig. 3. When screw is tightened, clamp holds plate on 
transformer.
MOUNTING PLATE AT LAMINATIONS
1. Remove the large rectangular knockout in the 
mounting plate as shown in Fig. 4.
2. Hold the transformer so the clamp on the end bell 
faces you.
3. With the keyhole slots up, fit the mounting plate 
over the primary leadwires and end bell. Insert 
small tab at the bottom of the plate into the slot in 
the transformer mounting foot.
4. Insert the mounting screw (supplied) through the 
holes as shown in Fig. 5. Secure the plate to the 
transformer, but do not overtighten the screw.
MOUNTING TRANSFORMER AND PLATE ON OUTLET BOX
The mounting plate can be mounted on 4 in. square 
boxes, 2 x 4 in. rectangular boxes, and on 4 in. octagonal 
boxes. See Fig. 4.
1. Align the plate with the box to determine the cor-
rect mounting holes. The mounting feet and sec-
ondary terminals are outside the box.
2. Remove the mounting hole knockouts, if neces-
sary. Mount the plate on the outlet box using two 
screws (obtained locally).
Mounting Through Outlet Box Knockout 
Hole
The transformer can be mounted on an outlet box using 
the clamp on the primary end bell. The mounting plate is 
not used. To mount the transformer on an outlet box:
1. Turn the clamp screw almost all the way out.
2. From outside box, thread the primary leadwires 
through suitable 7/8 in. knockout. Fit the clamp 
and screw through the knockout. Do not mount the 
transformer through a plastic knockout.
3. Tighten the clamp screw securely against the rim 
of the knockout. Avoid damaging the leadwires 
with the screwdriver.
Fig. 4. Use screwdriver to pry out both sections of 
knockout.
Fig. 5. Mounting screw and tab hold plate on transformer.
M12126
M9188A
WITH RAISED PORTION OF KNOCKOUTS FACING YOU:
PRY UP TOP SECTION OF LARGE KNOCKOUT 
BY INSERTING SCREWDRIVER FIRST AT ONE 
SIDE OF SLOT AND THEN AT THE OTHER SIDE.
1.
THEN PRY UP BOTTOM SECTION OF KNOCKOUT.
2.
REMOVE BOTH SECTIONS OF KNOCKOUT WITH PLIERS.3.
SHADED AREAS REPRESENT KNOCKOUTS 
AND SCREW SLOTS USED WITH 2 X 4 INCH
 OR OCTAGONAL OUTLET BOXES.
IMPORTANT
MOUNT
TRANSFORMER
OTHER SIDE
M9163
TRANSFORMER
PLATE




