This is the core requirement. For instance, a 10 mm² Class 2 copper conductor must not exceed a resistance of 1.83 Ω/km .

"I need the standard," Elias muttered to his junior engineer, Sarah. "I need to know exactly how the resistance is calculated for this class of conductor. I think they’ve undersized the stranding."

: Includes formulas and factors (Annex B) to correct resistance measurements for different ambient temperatures. iTeh Standards Where to Find IEC 60228 PDF Downloads

The standard requires that cables and accessories be marked with relevant information, including:

A single wire used for fixed installations where rigidity is acceptable. It offers the lowest resistance and cost.