There are two major concerns for sizing DC wiring from the output of a power provide to its load. They’re ampacity (fancy time period for the quantity of Amps) and voltage-drop (bear in mind ohms legislation: V = I x R). Ampacity refers to a protected present carrying stage as specified by security organizations similar to Underwriters Laboratories and the Nationwide Hearth Prevention Affiliation, which publishes the Nationwide Electrical Code (NEC).
AWG stands for American Wire Gauge and defines the diameter and cross sectional space of the wire. The smaller the AWG quantity, the bigger the diameter, cross-sectional space, and present carrying capability of the wire. All the time use insulated wires with stable or stranded pure copper conductors (don’t use aluminum or copper-clad metal wires). The voltage-drop is just the quantity of voltage misplaced in a size of wire as a result of resistance of the conductor.
DC wires could also be sized for both ampacity or voltage drop relying on the wire size and conductor heating. Generally, ampacity concerns will drive wire choice for brief wire lengths (lower than 50 toes) and voltage drop will drive wire choice for longer lengths (better than 50 toes). Observe: In case you are utilizing the Distant Sense feature of the power provide, bear in mind to remain inside the most voltage drop throughout the cables that the Distant Sense is designed to compensate for, which may vary from 0.3V to 1.0V (examine the power provide’s user-manual for particulars).
The Nationwide Electrical Code desk 310.16 supplies ampacity values for numerous sizes, bundles, and insulation temperature rated wires. ALWAYS FOLLOW THE NEC RULES, LOCAL CODES, AND YOUR COMPANY’S PRACTICES WHEN SELECTING DC WIRING.
Desk 1 reveals the MINIMUM advisable wire sizes for various load currents. The use of bigger diameter wires (with a smaller AWG quantity) would scale back the voltage drop (and warmth generated) throughout the wires. The present rankings in Desk 1 are primarily based upon utilizing 90° C rated insulated wire. If utilizing a decrease temperature rated insulated wire (e.g., 60° C), the wire diameter would must be bigger. Seek advice from the next website for extra details about wire gauges: http://en.wikipedia.org/wiki/American_wire_gauge .
For instance, per Desk 1 under, a load present of 200 Amps would require a minimal of two # 2 AWG wires linked in parallel for every of the output connections (one pair or wires for the optimistic (+) and one pair for destructive (-) output connections to the load). Once more, bigger diameter wires would lower the voltage drops throughout these wires.