990-91399A-001

Recommended Cable Sizes for UL

DANGER
hazard of electric shock, explosion, or arc flash
  • All wiring must comply with all applicable national and/or electrical codes.
  • The maximum allowable cable size is 500 kcmil.
  • Shrink sleeve must be fitted over cable lug crimped zone and must overlap with the cable insulation on all power cables.
Failure to follow these instructions will result in death or serious injury.

The maximum number of cable connections per busbar:

  • 4 on input/output/bypass busbars

  • 4 x 500 kcmil on input/output/bypass busbars

  • 4 x 500 kcmil or 8 x 300 kcmil on DC+/DC- busbars

  • 8 on N busbar

  • 16 on ground busbar

NOTE: Overcurrent protection is to be provided by others.

Cable sizes in this manual are based on Table 310.15 (B)(16) of the National Electrical Code (NEC) with the following assertions*:

  • 90 °C (194 °F) conductors (75 °C (167 °F) termination)

  • An ambient temperature of 30 °C (86 °F)

  • Use of copper or aluminum conductors

If the ambient temperature is greater than 30 °C (86 °F), larger conductors are to be selected in accordance with the correction factors of the NEC.

Equipment grounding conductors (EGC) are sized in accordance with the minimum requirements in NEC Article 250.122 and Table 250.122.

NOTE: 100% rated circuit breakers for UIB, UOB, MBB, SSIB. 100% rated breakers for battery breakers.

Copper

UPS rating 200 kW 250 kW 300 kW 350 kW 400 kW 450 kW 500 kW
Voltage (V) 480 480 480 480 480 480 480
Input phases (AWG/kcmil) 1 x 350 1 x 500 2 x 4/0 2 x 300 2 x 350 2 x 400 2 x 500
Input EGC (AWG/kcmil) 1 x 3 1 x 3 2 x 2 2 x 1 2 x 1/0 2 x 1/0 2 x 1/0
Bypass/output phases (AWG/kcmil) 1 x 250 1 x 350 1 x 500 2 x 4/0 2 x 250 2 x 300 3 x 350
Bypass EGC/output EGC (AWG/kcmil) 1 x 4 1 x 3 1 x 3 2 x 2 2 x 2 2 x 1 2 x 1/0
DC+/DC- (AWG/kcmil) 2 x 300 2 x 400 3 x 350 3 x 400 4 x 350 4 x 400 4 x 500
DC EGC (AWG/kcmil) 2 x 1 2 x 1/0 3 x 2/0 3 x 2/0 4 x 3/0 4 x 4/0 4 x 4/0

Aluminum

UPS rating 200 kW 250 kW 300 kW 350 kW 400 kW 450 kW 500 kW
Voltage (V) 480 480 480 480 480 480 480
Input phases (AWG/kcmil) 1 x 500 2 x 250 2 x 300 2 x 400 2 x 500 (3 x 300)* (3 x 400)*
Input EGC (AWG/kcmil) 1 x 1 2 x 1 2 x 1/0 2 x 2/0 2 x 3/0 3 x 3/0 3 x 3/0
Bypass/output phases (AWG/kcmil) 1 x 350 1 x 500 2 x 250 2 x 300 2 x 350 2 x 500 2 x 500
Bypass EGC/output EGC (AWG/kcmil) 1 x 2 1 x 1 2 x 1 2 x 1/0 2 x 1/0 2 x 2/0 2 x 3/0
DC+/DC- (AWG/kcmil) 2 x 500 3 x 300 3 x 500 4 x 350 4 x 500 5 x 400 5 x 500
DC EGC (AWG/kcmil) 1 x 2/0 3 x 3/0 3 x 4/0 4 x 4/0 4 x 250 5 x 350 5 x 350

Guidance for Organizing Input, Bypass, And Output Cables

NOTICE
Risk of equipment damage
To ensure correct load sharing in bypass operation in a parallel system:
  • All bypass cables must be the same length (within 10% deviation) for all UPSs.
  • All output cables must be the same length (within 10% deviation) for all UPSs.
  • All input cables must be the same length (within 10% deviation) for all UPSs (only required in single mains system).
Failure to follow these instructions can result in equipment damage.

The input, bypass, and output cables must be grouped in circuits. On raceways, use one of the two shown cable formations.

ECOnversion Limits for Parallel UPS Systems

ECOnversion requires a minimum load percentage on the UPS for parallel UPS systems. The minimum required load percentages depend on the power cable sizes.

NOTE: For installations using the recommended cable sizes, refer to the Standard ECOnversion Limits Based on Recommended Cable Sizes table for the minimum load percentages.

Standard ECOnversion Limits Based on Recommended Cable Sizes

UPS rating Minimum load %
200 kW 34%
250 kW 27%
300 kW 23%
350 kW 19%
400 kW 17%
450 kW 15%
500 kW 14%

The other prerequisites to use this table include:

  • The values are calculated based on the use of recommended cable sizes.

  • Installations with maximum two cables on each phase are supported.

  • The bypass and output cables must be the same length (within 10% deviation) for all UPSs.


NOTE: For certain installations such as installations with 80% breakers or where other installation methods have been applied to comply with the IEC standard, it is possible that non-recommended cable sizes will be used. For installations using non-recommended cable sizes, refer to the Standard ECOnversion Limits Based on Non-recommended Cable Sizes table for the voltage ratings percentages.

Standard ECOnversion Limits Based on Non-recommended Cable Sizes

UPS rating Minimum load %
200 kW 50%
250 kW 40%
300 kW 34%
350 kW 29%
400 kW 25%
450 kW 22%
500 kW 20%

The other prerequisites to use this table include:

  • The values are calculated based on the scenario of using non-recommended cable sizes.

  • Installations with three or four cables on each phase are supported.

  • The bypass and output cables must be the same length (within 10% deviation) for all UPSs.

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