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Wiring a home is about balancing ease of installation with safety and code compliance. In the residential world, the materials you choose are designed to be installed quickly within wood-framed walls while providing a lifetime of reliable power.

1. NM-B (Romex) - The Gold Standard

Non-Metallic Sheathed Cable (NM-B) is the primary choice for modern residential branch circuits. It consists of multiple insulated conductors wrapped in a flexible plastic jacket. Because it is lightweight and easy to "fish" through studs, it keeps labor costs significantly lower than conduit-based systems.

Pros: No conduit required, easy to strip, and highly affordable for 15A and 20A circuits.

2. Plastic (PVC) Boxes - Cost and Speed

In residential "New Work," blue or grey plastic boxes are the standard. They are non-conductive, meaning the box itself doesn't need to be grounded, and they often feature built-in cable clamps that save time during "rough-in."

Note: While plastic is the standard, steel boxes are still required in some jurisdictions (like Chicago) or when using surface-mount wiring in a garage or basement.

3. AFCI & GFCI Protection

Modern residential codes focus heavily on life safety. Arc-Fault Circuit Interrupters (AFCI) are now required in most living areas to prevent fires, while Ground-Fault (GFCI) protection is mandatory near water sources. Using high-quality devices here is the best way to prevent "nuisance tripping."

Commercial electrical work is built for durability and future-proofing. Unlike residential wiring, commercial systems are often exposed to physical stress, higher voltages, and the need for constant modifications as businesses grow and change.

1. EMT (Electrical Metallic Tubing) - The Backbone

EMT is the thin-walled steel conduit used in almost all commercial environments. Because it can be bent and coupled, it creates a "raceway" that allows wires to be pulled in or out later without opening walls. It also provides an excellent equipment grounding path.

2. THHN/THWN-2 - High-Performance Wire

In commercial conduit, we use individual THHN conductors rather than Romex. These wires feature a tough nylon jacket that resists heat, oil, and moisture. They are rated for $90^\circ C$ and are designed to be pulled through long runs of conduit with ease.

3. Metal Boxes and MC Cable

Steel boxes are the rule in commercial work. They offer fire resistance and structural strength. MC (Metal Clad) Cable is often used for "whips"—the final few feet from a junction box to a light fixture or piece of machinery—offering flexibility without sacrificing protection.

"A hallmark of a professional commercial job is the 'cleanliness' of the conduit bends. Properly supported EMT is not just a code requirement; it’s a sign of quality craftsmanship."