19
0100037-J0 Rev C
Table B — Cable size equivalents (AWG to Metric)
Cable size
(see notes 1 and 2)
Circular mils
Square millimeters
Equivalent metric
cable
0000 AWG (or 4/0)
211600
107.2
120
313 MCM (or kcmil)
313600
159
150 or 185
350 MCM (or kcmil)
350000
177.36
185
373 MCM (or kcmil)
373700
189
185 or 240
500 MCM (or kcmil)
500000
253.36
300
535 MCM (or kcmil)
535300
271
300
750 MCM (or kcmil)
750000
380.00
400
777 MCM (or kcmil)
777700
394
400
7.1.2 Recommended Torque Values
Table C lists the recommended torque values for connection to the power system with the following hardware:
• Clear hole connections (nut and bolt)
• PEM studs
• PEM threaded inserts
• Thread formed connections (in copper bus bar)
Grade 5 rated hardware is required for these torque values.
Table C — Recommended torque values
1/4"
8.8 ft-lbs
3/8"
32.5 ft-lbs
1/2"
73 ft-lbs
7.2 Grounding
This power system is suitable for installation as part of a Common Bonding Network (CBN) and is intended to be
used in a DC-C configuration (common DC return).
Connect the isolated power system battery return bus (BRB) to the building master ground bus (MGB), or floor
ground bus (FGB) in a larger building. This acts as a system reference and as a low impedance path to the ground
for surges, transients, noise, etc. The MGB or FGB must have a direct low impedance path to the building grounding
system.
The cable from the power system to the MGB or FGB must be sized to provide sufficient ampacity to clear the larg-
est fuse or breaker on the power system, excluding the battery protection fuse or circuit breaker. 750 MCM is rec-
ommended. This is the minimum requirement. Other factors including the length of the cable and special grounding
requirements of the load must also be factored in. The insulated cable must be equipped with two-hole crimp type
lugs and must not have any tight bends or kinks.
Table D — Typical ground reference conductor selection
Power system ampacity
Ground reference conductor size
< 30A
#10
30 – 100A
#6 to #2
100 – 400A
0000
400 – 800A
350 MCM
> 800A
750 MCM
The power system frame must also be connected to the MGB or FGB for personnel safety and to meet many tele-
com grounding requirements. Each rack must have its own frame or site ground connection.
