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Conductor and Conduit Sizing
152315 Rev C 2–11
Conductor and Conduit Sizing
All wiring methods and materials shall be in accordance with the National
Electrical Code ANSI/NFPA 70. When sizing conductors and conduits interfacing
to the PV100S, both shall be in accordance with the National Electric Code
ANSI/NFPA 70, as well as all state and local code requirements.
Large gauge wire must conform to the minimum bend radius dependent upon the
wire gauge (refer to the National Electric Code, Article 373-6B (Ninth Edition).
The following provides information on sizing the conductors and conduits for the
system.
To calculate the proper conduit size:
1. Determine the required cable ampacity.
2. Determine the conduit length between the inverter and the transformer.
3. Determine the proper size for the cable according to the allowable ampacities
indicated by NEC Table 310.16 (Ninth Edition).
4. Determine the proper size for the conduit.
The following is an example of the steps outlined above. Assumptions were made
in this example which may not match your application, and the resulting design
may not comply with all code requirements. Consult a licensed electrician on
recommendations for specific installations.
Step 1. Determine the required cable ampacity.
AC Phase Cables from Inverter to Transformer:
100 kW / 208 Vac / 1.732 = 277.5 A
rms
(full load current)
277.5 x 125% = 347 A (required ampacity)
Step 2. Determine the conduit length between inverter and transformer.
• If the conduit length between the inverter and the transformer is less than
24 inches, then the cable can be sized using the NEC Table 310.16
(in Raceway) (Ninth Edition).
• If the conduit length is greater than 24 inches, then the cable must be sized
using NEC Table 310.16 (in Raceway) (Ninth Edition) and by using the
adjustment factors in NEC TAble 310-15(b)(2)(a).
CAUTION: Equipment Damage
Be careful to keep the wire bundles away from any sharp edges which may damage wire
insulation over time.