INSTALLATION
1
To prevent malfunction or shortened life, protect
the switch from construction grit and metal chips.
Mounting:
Two
Outline and Mounting Diagrams
are
furnished; one for enclosed switches, the other for open–
type switches. Select the appropriate diagram and mount
the RC Switch (in any position). All mounting details
and instructions are shown on the diagram.
RC Switches on subpanels must be mounted with
supplied insulator bushings and insulator pieces.
Be sure the insulator pieces are behind the switch
and use the insulator bushings under the hardware.
Figure 1. Required insulator bushings and backing
insulators for RC Switches mounted on subpanels.
Service Connections:
For panelboard mounting, the
extended bus plates provide both the mechanical support
and the electrical connection. Switches on subpanels are
furnished with solderless lugs for copper or aluminum wire.
Outline and Mounting Diagram
lists wire sizes accepted.
Remove surface oxides from wires by cleaning with a wire
brush. When aluminum conductor is used, apply joint
compound to conductor. Tighten conductor and carefully
wipe away excess compound. Maintain proper electrical
clearance between live metal parts and grounded metal.
Control Line Connections:
Control circuit connections
designated
L
,
O
,
C
are supplied with clamp type
terminals. These terminals accept wire sizes #14–10
AWG Cu. Simply insert appropriate control wires and
tighten terminal clamp screws. See the
Wiring Diagram
.
Tighten all electrical connections; refer to the
torque specified on the label on the RC Switch.
Table A lists the maximum distances and minimum wire
sizes that can be run between a control station and one
ASCO 920 switch.
Table A – Line Run
Min.
Wire Size
Maximum Distance (feet)
1
for these AC Control Voltages
Wire Size
AWG
120 V
208 V
240 V
277 V
14
12
10
750
1200
2000
1650
2600
4200
2760
4300
6900
3950
6350
10000
1
For ambient temperatures to 40
˚
C.
Do not exceed these distances
for proper switch operation.
Line run can be extended by use of Auxiliary Control
Relays. See page 3.
Table B provides the ASCO 920 coil inrush current and
minimum control circuit fuse sizes.
Table B – Inrush Current / Minimum Fuse
Amps
Inrush Current / Fuse (amps)
2
for these AC Control Voltages
Amps
120 V
208 V
240 V
277 V
480 V
Inrush
11.3
5.15
6.4
7
7
Fuse
3
1.5
1.5
1.5
3
2
Fuse value listed will also protect ASCO 920
against abnormal operating conditions.
MAINTENANCE
Annual preventive maintenance will insure high
reliability and long life for the ASCO 920 RC Switch.
Keep the Switch clean.
De–energize all sources, then
brush and vacuum away any excessive dust accumulation
.
Maintain Switch Lubrication.
Under normal service,
relubrication is not required. Renew factory lubrication
if switch is subjected to severe dust or abnormal
operating conditions, and if the coil is replaced. Only use
Lubrication Kit 625549; do not use oil or any other type
of lubricant
.
Inspect Main Current–Carrying Contac
ts.
De–energize all sources, then remove cover to check
contact condition. Discoloration or slight pitting does
not affect contact efficiency. Replace the contacts when
they become pitted, excessively worn, or appear to be
overheated.
The arc chutes are held in place by the cover.
If the arc chutes are removed, be sure they are
put back in place with “top” visable. Make sure
the cover is fully seated before tightening the
cover screws. (Do not over–tighten).
