Changes to Service Conductor Sizing in the 2023 NEC Section 230.42

[jar546]

Changes to Service Conductor Sizing in the 2023 NEC: An Overview of Section 230.42​

The 2023 National Electrical Code (NEC) introduced important updates to Section 230.42, specifically regarding the minimum size and ampacity of service-entrance conductors. These updates include the addition of two new subsections, A(1) and A(2), focusing on continuous and noncontinuous loads, and the application of adjustment factors. Here's a detailed look at these changes and their implications.

(A) General Requirements​

Service-entrance conductors must have an ampacity not less than the maximum load to be served. The conductors should be sized based on the largest value obtained from either A(1) or A(2). The loads are determined according to Part III, IV, or V of Article 220, as applicable, and the ampacity is derived from Section 310.14, ensuring compliance with 110.14(C). Additionally, the maximum current rating of busways must align with the value for which the busway has been listed or labeled. This ensures that all service-entrance conductors are adequately sized to handle the expected electrical load, providing a safe and reliable electrical system.

(A)(1) Continuous and Noncontinuous Loads​

This subsection stipulates that when service-entrance conductors supply continuous loads or a mix of continuous and noncontinuous loads, the minimum conductor size must have an ampacity that is not less than the sum of noncontinuous loads plus 125% of continuous loads. This calculation ensures that the service-entrance conductors can handle sustained loads effectively.

Exceptions:

1. Grounded conductors not connected to an overcurrent device can be sized at 100% of the sum of continuous and noncontinuous loads.
2. If the service-entrance conductors terminate in an overcurrent device where both the device and its assembly are listed for operation at 100% of their rating, then the sum of noncontinuous and continuous loads can be used.

These exceptions provide flexibility in specific scenarios, allowing for more efficient conductor sizing while maintaining safety standards.

(A)(2) Application of Adjustment or Correction Factors​

This new section mandates that the minimum service-entrance conductor size must have an ampacity no less than the maximum load to be served after applying any necessary adjustment or correction factors. These factors account for conditions such as ambient temperature and conductor bundling, ensuring that the conductor can safely carry the required load under various environmental and installation conditions.

(B) Specific Installations​

In addition to the general requirements outlined in 230.42(A), subsection (B) specifies that the minimum ampacity for ungrounded conductors in particular installations must not be less than the rating of the service disconnecting means specified in 230.79(A) through (D). This ensures that the conductors are appropriately sized for the specific service disconnecting means used in the installation.

(C) Grounded Conductors​

Grounded conductors must be sized no smaller than the minimum size required by 250.24(D). This requirement ensures that grounded conductors are adequately sized to handle fault currents and maintain the integrity of the electrical system.

 

[wwhitney]

There was no change to the text of 230.42 in the 2023 NEC. The only change was to the formatting and section headings.

Cheers, Wayne

 

[ICE]

There was no change to the text of 230.42 in the 2023 NEC. The only change was to the formatting and section headings.

Cheers, Wayne

I'm sorry Jeff but I had to smile when I read this. Oh Hell smile? I LOL.
You know if your friends can't laugh ... you can't either.

 

[jar546]

I'm sorry Jeff but I had to smile when I read this. Oh Hell smile? I LOL.
You know if your friends can't laugh ... you can't either.

Neither of you understands what I am trying to do.

 

[ICE]

Neither of you understands what I am trying to do.

Perhaps not but I know what you did.

 

[wwhitney]

Neither of you understands what I am trying to do.

I'm not making a commentary on what you are trying to do, just offering a correction to the OP.

Cheers, Wayne