Electrical Wire

Select wire gauge based on the maximum current (amps) the circuit will carry and the allowable voltage drop; common residential gauges are 14 AWG for 15 A, 12 AWG for 20 A, and 10 AWG for 30 A. Choose conductor type (copper vs. aluminum) based on conductivity and application—copper has higher conductivity and is preferred for most interior wiring, while aluminum is lighter and used in some service and feeder applications—and ensure the wire insulation and rating match the application (e.g., THHN, NM-B, or UF for outdoor/buried runs)

Match the insulation type to the installation environment: THHN/THWN for conduit and higher temperature ratings, NM-B for dry interior residential walls, and UF for direct burial; check the voltage rating (commonly 300 V or 600 V for building wire) and temperature rating (typically 60°C, 75°C, or 90°C) to ensure compatibility with connectors and devices. Use wires with moisture- and sunlight-resistant jackets for outdoor or wet locations and confirm local code requirements for permitted insulation types

Measure the total run length from source to load and add extra for routing, terminations, and mistakes; multiply by the number of conductors in the run. To limit voltage drop keep the run length and current in mind—use larger gauge wire for long runs or high-current circuits, and consult voltage-drop tables or calculators to maintain drop under recommended levels (often 3% for branch circuits)

Look for wire marked with recognized safety listings or standards such as UL, CSA, or equivalent local certification marks, and ensure the wire type and installation method comply with the National Electrical Code (NEC) or your local electrical code. Verify conductor sizing, insulation type, and ambient temperature ratings meet code requirements for the intended application and that any building permits and inspections are obtained when required

Store spools on a dry, cool surface away from direct sunlight and chemicals; keep ends protected to prevent moisture ingress and physical damage. When handling, avoid sharp bends and kinks, do not drag wire over rough edges, and unspool in a way that prevents twisting or coil memory that can make installation difficult

Price varies with conductor material (copper is typically more expensive than aluminum), gauge (thicker wire costs more), insulation type and ratings, and spool length; budget options and small specialty leads can be under $50, while long runs, larger-gauge building wire, or industrial-grade cables can be in the $25 to $500 range depending on specifications. Consider total project length and required ratings when comparing costs, not just unit price

Hire a licensed electrician for any work involving service panels, new branch circuits, meter connections, or when local code or permits are required, and whenever you lack experience with wiring and testing safety-critical connections. Complex projects, high-voltage equipment, or installations that affect building code compliance should be performed or inspected by a qualified professional