Operating instructions

Installation 11
1.2.1 Input And Output Power Connections
If the unit is furnished with input junction boxes, the input power connections are made to the
input power terminals located in the junction boxes. Input power cables, furnished with the input
junction boxes, are shipped unattached to the unit for connection between the junction boxes and
the lugs provided inside the unit.
If junction boxes are not furnished, the input power connections are made to the lugs provided
inside the unit.
Output power connections are made to the lugs provided inside the unit. See unit wiring diagrams
furnished with the unit.
The two input power feeds to the Static Switch should be from two independent sources to avoid a
common source failure. Further, to ensure proper operation of the Static Switch, the two input
sources must be the same nominal voltage level and phase rotation. For uninterrupted automatic
transfer, the two input sources should be synchronized within 15 degrees.
The Static Switch is designed for operation with 3- or 4-wire solidly grounded sources only. For 4-
wire operation, the common source neutral must be connected to the Static Switch. See Figure 7
for a typical one-line diagram. Refer to the unit wiring diagram.
The input and output power wire size should be based on the upstream overcurrent protection
device, observing the NEC and local codes. If the Static Switch is bolted to the Precision Power
Center, the intra-cabinet interconnecting wiring can be sized based on NEC Table 310-17.
The molded case switches contained in the Static Switch are typically non-automatic circuit
breakers that rely on the upstream and/or load overcurrent protection. Upstream overcurrent pro-
tection should be rated equal to or less than the rating of the Static Switch molded case breakers.
The Static Switch input and output power and ground lugs accommodate a wide range of wire
sizes:
!
WARNING
RISK OF ELECTRIC SHOCK
VERIFY THAT ALL INPUT POWER AND CONTROL CIRCUITS
ARE DE-ENERGIZED AND LOCKED OUT BEFORE MAKING
CONNECTIONS INSIDE UNIT.
!
WARNING
RISK OF UNIT DAMAGE
THE INPUT SOURCES TO THE STATIC SWITCH MUST BE
GROUNDED-WYE SOURCES. INPUT SOURCES OTHER THAN
SOLIDLY GROUNDED-WYE SOURCES MAY CAUSE DAMAGE TO
THE SWITCH.
Switch Size Power and Ground Lug Wire Range
100 amp #14 to #2/0 AWG
250 amp #4 AWG to 350 kcmil
400 amp (2)#4 AWG to (2) 350 kcmil
600 amp (2)#4 AWG to (2) 350 kcmil
800 amp (3) #2/0 AWG to (3) 500 kcmil power
(3) #4 AWG to (3) 350 kcmil ground
1200 amp (4) #2/0 AWG to (4) 500 kcmil power
(4) #4 AWG to (4) 350 kcmil ground