What is NM-B Wire and What Size Do You Need: 14/2 & 12/2 Explained

NM wire is simply electrical wire wire with an outermost sheathing made of Non-Mettalic PVC. It is commonly referred to as Romex® or SLiPWire®. Both of these are just brands of NM (Non Metallic sheathed) wire that belong to companies Southire and Cerrowire respectively, but many more companies sell NM type wire, including Hulk Tech Hardware. The B in NM-B stands for a heat rating of 194°F, which ensures the internal wires can operate without overheating.

Choosing the correct NM-B wire for your project is essential for safety and code compliance. If you’re working on home wiring, the two most common sizes you’ll encounter are 14/2 and 12/2 NM-B wire. This guide explains what these numbers mean, when to use each type, and how to ensure your circuits meet local building requirements.

What Does 14/2 or 12/2 Mean?

The first number refers to the gauge (thickness) of the wire:

• 14 AWG is thinner and handles less current.

• 12 AWG is thicker and supports more current.

The “/2” indicates the wire includes two insulated conductors (black and white) plus a bare ground wire inside the cable sheath:

• Black wire (hot): Carries power to your outlet or fixture.

• White wire (neutral): Completes the circuit by carrying current back to the panel.

• Bare copper (ground): Safely discharges stray electricity, preventing shocks.

*Read this guide to learn more about NM wire that includes three insulated conductors, such as Hulk Tech’s 12/3 and 14/3 Easy Pull NM-B wire.

When to Use 14/2 NM-B Wire

• Gauge: 14 AWG

• Max Amperage: 15 amps

• Use Cases:

  • Bedroom outlets

  • Living room lighting circuits

  • Hallways and other light-duty areas

This wire is ideal for circuits that don’t draw a lot of current. It requires a 15-amp breaker to prevent overload.

Note: Never use 14/2 wire for circuits that could exceed 15 amps, such as kitchens or bathrooms, as it can overheat and create a fire hazard.

When to Use 12/2 NM-B Wire

• Gauge: 12 AWG

• Max Amperage: 20 amps

• Use Cases:

  • Kitchens (for appliances like microwaves and coffee makers)

  • Bathrooms (where hairdryers and other high-power devices are used)

  • Garages or workshops (for tools)

Since 12/2 wire can handle higher loads, it’s required by code for circuits with 20-amp breakers. These circuits are essential in areas where appliances or tools might draw more power.

Key Differences Between 14/2 and 12/2 NM-B Wire

• Current Capacity: 14/2 supports up to 15 amps, while 12/2 supports 20 amps.

• Breaker Requirement: Pair 14/2 with a 15-amp breaker and 12/2 with a 20-amp breaker.

• Wire Thickness: 12/2 is thicker, making it suitable for high-demand areas like kitchens, bathrooms, and garages.

• Code Compliance: Local building codes may require 12/2 wire in kitchens and bathrooms to meet higher power needs.

Conclusion

Choosing the right Hulk Tech wire size is crucial to ensure safety and efficiency. Use 14/2 NM-B wire for lighting circuits or outlets in light-use areas like bedrooms and living rooms. For kitchens, bathrooms, and garages, 12/2 NM-B wire will safely handle higher loads. Always follow local electrical codes and consult a licensed electrician if you’re unsure about your installation.

Disclaimer:
This blog post is intended for informational purposes only and should not be considered professional advice. Electrical work can be dangerous if not performed correctly. Always consult national and local building codes to ensure compliance with regulations. We strongly recommend working with or seeking advice from a licensed electrician or electrical professional to ensure your project is installed safely and meets all applicable standards. Use this information at your own risk.