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3

69-0251—2

Fig. 4—Use screwdriver to pry out both
sections of knockout.

Fig. 5—Mounting screw and tab hold plate on
transformer.

IMPORTANT
MOUNT
TRANSFORMER
OTHER SIDE

M9163

TRANSFORMER

PLATE

1. Align the plate with the box to determine the proper

mounting holes. The mounting feet and secondary termi-
nals will be outside the box.

2. Remove the mounting hole knockouts if necessary.
3. Mount the plate on the outlet box using two screws

(obtained locally).

MOUNTING THROUGH OUTLET BOX
KNOCKOUT

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.

2. Tighten the clamp screw securely against the rim of

the knockout. Avoid damaging the leadwires with the
screwdriver.

WIRING

All wiring must comply with local codes and ordi-

nances. Disconnect power before making wiring connec-
tions to prevent electrical shock or equipment damage.

1. Make primary connections to the line voltage power

supply. On multitap models, be sure to use correct leads for
available power supply. See Fig. 6.

2. On multitap models, insulate the ends of the unused

leads using wire nuts or capping with a solderless connec-
tor.

3. Make secondary connections to 24 Vac control cir-

cuit.

To mount the plate at the laminations:

1. Remove the large rectangular knockout in the mount-

ing 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 may be mounted on 4 in. square

boxes, 2 x 4 in. rectangular boxes, and on 4 in. octagonal
boxes. See Fig. 4.

M9188

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.

Summary of Contents for AT120A, AT140A, AT150A, AT175A

Page 1: ...inals 50 VA AT175A 120 208 240 9 in leads 27 5 24 0 Screw terminals 75 VA Installation WHEN INSTALLING THIS PRODUCT 1 Read these instructions carefully Failure to follow them could damage the product or cause a hazardous condition 2 Check the ratings given in the instructions and on the product to make sure the product is suitable for your application 3 Installermustbeatrained experiencedservicete...

Page 2: ... leadwires through the round center hole in the plate 4 Fit the clamp and screw through the round hole 5 While holding the plate in place tighten the setscrew securely against the rim of the hole See Fig 3 Avoid damaging the leadwires with the screwdriver Fig 3 When screw is tightened clamp holds plate on transformer PLATE MOUNTED AT CLAMP ON PRIMARY END BELL MOUNTING PLATE MOUNTING PLATE PLATE MO...

Page 3: ...pment damage 1 Make primary connections to the line voltage power supply On multitap models be sure to use correct leads for available power supply See Fig 6 2 On multitap models insulate the ends of the unused leads using wire nuts or capping with a solderless connec tor 3 Make secondary connections to 24 Vac control cir cuit To mount the plate at the laminations 1 Removethelargerectangularknocko...

Page 4: ...easure voltage again If proper primary voltage is measured and sec ondary voltage is significantly less than the volt age shown on the regulation curves transformer winding is damaged Replace transformer and repeat checkout procedures If primary voltage is 0V assure power supply is connected properly or repair if necessary Repeat checkout procedures 5 Do not put system into operation unless correc...

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