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The following are guidelines only and superseded by local regulations and codes of practice where
applicable:
• Take special care when determining the size of the neutral cable (grounded conductor), because
current circulating on the neutral cable may be greater than nominal current in the case of non-
linear loads. Refer to the values in Table 6.
• The grounding conductor should be sized according to the fault rating, cable lengths, type of pro-
tection, etc. The grounding cable connecting the UPS to the main ground system must follow the
most direct route possible.
• Consideration should be given to the use of paralleled smaller cables for heavy currents, as this
can ease installation considerably.
2.2.1
Power Cable Connection Procedure
The rectifier input, bypass, output and battery power cables (all require lug type terminations) are
connected to busbars situated in the I/O section as shown in Figures 7 through 9.
Equipment Ground
The equipment ground busbar is located in the I/O section as shown in Figure 7. The grounding con-
ductor must be connected to the ground busbar and bonded to each cabinet in the system.
All cabinets and cabling should be grounded in accordance with local regulations.
NOTE
Proper grounding reduces problems in systems caused by electromagnetic interference.
WARNING
!
Failure to follow adequate grounding procedures can result in electric shock hazard to
personnel, or the risk of fire, should a ground fault occur.
All operations described in this section must be performed by properly trained and qualified
electricians or technical personnel. If any difficulties are encountered, contact Liebert
Services. See the back page of this manual for contact information.
The grounding and neutral bonding arrangement must be in accordance with local and
national codes of practice.
Once the equipment has been positioned and secured, connect the power cables as described below
(refer to the appropriate cable connection drawing in 4.0 - Installation Drawings):
1. Verify that the UPS equipment is isolated from its external power source and all the UPS power
isolators are open. Check that these supplies are electrically isolated and post any necessary
warning signs to prevent their inadvertent operation.
2. Open exterior and interior panels on the front of the I/O.
3. Connect the ground and any necessary main bonding jumper to the equipment ground busbar
located in the I/O section.
4. Make power connections and tighten the connections to the proper torque according to one of the
two procedures below, depending on the type of installation:
Ensure correct phase rotation.
• Top Cable Entry (see Figure 8)
• Bottom Cable Entry (see Figure 9)
Top Cable Entry
When making the power connections for top cable entry, the recommended order of pulling
and installing cables is to start from the top connections to the bottom connections. The cables
must be routed around the fault braces (see Detail in Figure 8). This is to prevent the cables
from contacting other busbars. The recommended conduit layout is shown in Figure 7.
7
UPS Electrical Installation
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