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  • ⚡ Code Corner: 🔸 NEC 210.21(B)(3) – Receptacle Ratings for Branch Circuits

⚡ Code Corner: 🔸 NEC 210.21(B)(3) – Receptacle Ratings for Branch Circuits

Sharpen your knowledge with a quick dive into the NEC.

Author

Chris Martinez
July 17, 2025

📘 What NEC 210.21(B)(3) says:

This section covers what rating a receptacle must have when it's connected to a branch circuit — specifically when more than one receptacle is on a branch circuit.

For branch circuits with more than one receptacle (like standard duplexes), the receptacle's rating must not be less than the branch circuit's rating. But there are exceptions depending on the amperage of the circuit.

🔧 Why it matters:
Choosing the wrong receptacle rating can lead to:

  • Code violations that get flagged during inspection

  • Overheating or damage if the load exceeds the receptacle’s limit

  • Unnecessary cost from using higher-rated receptacles where not required

  • Confusion for apprentices or inspectors reading mismatched labels

Knowing when 15A receptacles are allowed on 20A circuits helps you stay compliant without overbuilding, especially in kitchens, living rooms, and commercial office spaces.

💡 Pro Tip:
Use duplex 15A receptacles on 20A kitchen appliance circuits — it’s code compliant as long as there’s more than one receptacle.

🧠 Code Quiz

NEC 210.21(B)(3) – Receptacle Ratings for Branch Circuits

📘 Scenario:
You're wiring a commercial office space with 20A general-purpose branch circuits. The electrician installs multiple 15A duplex receptacles on one of the circuits.

❓Question:
Is this installation compliant with NEC 210.21(B)(3)?

💭 Think it through:
Does the code ever allow 15A receptacles on a 20A circuit? What condition must be met?

✅ Answer: Yes, it's compliant — as long as there is more than one receptacle on the circuit.
This is directly allowed by NEC 210.21(B)(3).

📖 Reference:

“A single receptacle on an individual branch circuit shall have an ampere rating not less than that of the branch circuit. Where connected to a branch circuit supplying two or more receptacles... each receptacle shall have an ampere rating not less than the rating listed in Table 210.21(B)(3).”
→ Table 210.21(B)(3) shows that 15A receptacles are allowed on 20A circuits when there are two or more on the same branch.