210.24(1) Summary of Branch-Circuit Requirements- Copper Conductors.
The Historical Stance
The evolution of the National Electrical Code (NEC) is evident with each iteration, addressing issues and gaps present in its previous editions. A vital component of this evolution is ensuring clarity in interpreting the Code and ensuring that electricians can safely and efficiently navigate its regulations. A pressing matter in recent times, especially noted among electricians, pertained to Section 110.5 Conductors and its implications.
Historically, Section 110.5 of the NEC has been quite definitive in its stance. If not otherwise specified, the conductor sizes mentioned in any section of the Code were applicable to copper conductors. But there’s a caveat: conductors designed to carry current were bound to be of copper, aluminum, or copper-clad aluminum. This posed a unique challenge. Copper conductors inherently allow a higher ampacity than their aluminum and copper-clad aluminum counterparts. The reason? The latter heats up more for the same current when compared to pure copper conductors.
New for the 2023 NEC, Table 210.24(2) now recognizes the branch circuit ratings of aluminum conductors, and the revised Tables include information for 10-ampere branch circuits.
2023 NEC - What has changed?
2020 NEC
In the 2020 NEC, there's a table called Table 210.24 that specifically deals with branch-circuit requirements for copper conductors. It's important to note that this table only provides information for copper conductors and doesn't offer guidance for aluminum or copper-clad aluminum conductors. However, the 2020 NEC does allow the use of aluminum and copper-clad aluminum conductors in branch circuits, as mentioned in Section 110.5.
If an electrician decides to use aluminum or copper-clad aluminum conductors in a branch circuit and follows the minimum ampacity and overcurrent protection values listed for copper conductors in Table 210.24, those aluminum or copper-clad aluminum conductors won't meet the minimum requirements.
Another thing to note is that Table 210.24 in the 2020 NEC exclusively focuses on copper conductor branch circuits with ratings of 15 amperes or higher. It doesn't include information about 10-ampere circuits. This omission is because the 2020 NEC didn't recognize 10-ampere branch circuits, especially those with 10-ampere overcurrent protection devices.
2023 NEC
In the 2023 NEC, Table 210.24 has undergone significant changes, splitting into two separate tables: Table 210.24(1) and Table 210.24(2). This alteration replaces the single table found in the previous Code cycle. Table 210.24(1) outlines the minimum requirements for branch circuits using copper conductors, while Table 210.24(2) details the minimum requirements for branch circuits employing aluminum and copper-clad aluminum conductors.
A notable update in the revised 2023 tables is the introduction of a 10A column in both tables. This signifies a change in the NEC's stance, as it now officially acknowledges 10-ampere branch circuits as valid, albeit with certain limitations, in the 2023 Code cycle. The 2023 Code provides guidance on 10-ampere branch circuits and permits their installation in various contexts. Sections 210.23(A)(1) and (A)(2) are examples of such guidance:
Section 210.23(A)(1) titled "Loads Permitted for 10-Ampere Branch Circuits" specifies that a 10-ampere branch circuit is allowed to supply power to one or more of the following:
- Lighting outlets.
- Dwelling unit exhaust fans on bathroom or laundry room lighting circuits.
- A gas fireplace unit supplied by an individual branch circuit.
Section 210.23(A)(2) titled "Loads Not Permitted for 10-Ampere Branch Circuits" clarifies that a 10-ampere branch circuit is not suitable for any of the following purposes:
- Receptacle outlets.
- Fixed appliances, except when specifically permitted for individual branch circuits.
- Garage door openers.
- Laundry equipment.
The 2023 Code in Action
The revisions in the 2023 NEC speak volumes about the intent to ensure clarity, safety, and efficiency in electrical installations. By differentiating between copper and aluminum conductor requirements and recognizing the 10-ampere branch circuits, the NEC has significantly reduced ambiguities. As the electrical world continues to evolve, so too does the NEC, ensuring that its regulations are in tandem with the needs and realities of the field. Electricians can now breathe a sigh of relief, having a Code that addresses their concerns head-on.