Code Change Summary: A new provision in Section 690.4(G) now permits PV current and voltage calculations to be rounded to the nearest whole number.

SME commentary: The 2026 NEC^® introduces a new allowance in Section 690.4(G) that brings clarity to a common point of uncertainty in photovoltaic design calculations. The new text permits calculations to be rounded to the nearest whole number, with decimal fractions smaller than 0.5 dropped. This language mirrors an existing rule in 220.5(B), which allows branch-circuit, feeder, and service load calculations to use similar rounding practices. By adopting parallel treatment for PV circuits, the Code aligns these sections and removes ambiguity that previously required designers to infer that the 220.5(B) rule might apply outside of Article 220.

This new rule applies specifically to calculations in Article 690, but similar changes occurred in 705 and 706. These articles address PV systems, interconnected power production sources, and energy storage systems, each of which uses current and voltage values that often include decimal fractions arising from module ratings, temperature coefficients, and adjustment or correction factors. Without direction from the Code, field practice varied on when or whether rounding was appropriate. The new language eliminates that inconsistency.

For PV system calculations, this allowance applies to both current and voltage values. The placement of the new rule directly in 690.4 (addressing general requirements for the article itself) ensures that the provision is easily recognized and correctly applied during design and review of maximum circuit current, maximum voltage, and the ratings of wiring methods and equipment.

The substantiation for this change explained that there has never been a standard approach for handling fractional values for PV circuits. Typical PV circuits are not branch circuits or feeders, so the Article 220 rule did not strictly apply. PV module ratings often include several decimal places due to manufacturing tolerances and standardized test conditions. Voltage calculations in particular may produce decimal values affected by temperature multipliers, and those digits brought confusion in the past regarding rounding up or down without clear code language.

The final language clarifies that rounding to the nearest whole number is acceptable for any qualifying PV calculation. The CMP statement reinforces this by noting that the new text is modeled on the established rules in 220.5(B). This addition removes an uncertainty that many designers have navigated for years and results in more uniform application of current and voltage values throughout Articles 690, 705, and 706.

Below is a preview of the NEC^®. See the actual NEC^® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2026 NEC^® edition of NFPA 70.

2023 Code Language:

This code language did not exist.

2026 Code Language:

N 690.4(G) Fractions of an Ampere or Volt. Calculations shall be permitted to be rounded to the nearest whole number, with decimal fractions smaller than 0.5 dropped.