Quick Answer
For DC breakers in solar setups, use wiring that can handle the high currents and voltage drops associated with photovoltaic (PV) systems. THHN (Thermoplastic-Insulated Hybrid Nylon) or THWN (Thermoplastic-Insulated Wire with Nylon Jacket) wire is commonly used for DC wiring due to its durability and resistance to high temperatures.
Choosing the Right DC Breaker Wire Size
When selecting wire for DC breakers, it’s essential to consider the system’s maximum DC current output. The wire size must be large enough to handle this current without overheating or suffering damage. As a general rule, use wire with a minimum ampacity rating of 125% of the DC breaker’s current rating. For example, if you have a 20A DC breaker, use 25A-rated wire.
DC Breaker Wire Gage and Ampacity
To ensure safe operation, consider the wire gage (AWG) in addition to ampacity. A lower gage number indicates a larger wire diameter and greater current-carrying capacity. For example, a 4/0 AWG wire has a larger diameter than a 6 AWG wire, allowing it to handle higher currents. When in doubt, consult the wire manufacturer’s specifications and the National Electric Code (NEC) for guidance on sizing DC wire for solar setups.
Solar Breaker Sizing and Wire Selection
When sizing DC breakers and selecting wire for solar setups, consider the system’s total DC power output. This includes the sum of all PV modules, controllers, and loads. A common mistake is undersizing the DC breaker or wire, which can lead to overheating, system damage, or even a fire. To avoid these risks, calculate the system’s maximum DC current output and choose wire with a sufficient ampacity rating.
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