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In the previous issue, we started to look at the few ways Article 215 affects your calculations. We left off with the 125% rule presented in 215(A)(1). This same rule is presented in 215.3 for sizing overcurrent protection devices.
The other Article 215 requirements that could affect your calculations are in Subsection 215, which is divided into Point A (Under 600V) and Point B (Over 600V). Let’s look at what those are.
That second bullet point above is confusing to many people. If the feeder conductors and the service conductors are carrying the same load, wouldn’t they be sized at the same ampacity anyhow?
It might seem so at first glance. But you size feeder conductors per the requirements of 215.2 and service conductors per the requirements of Article 230 (different subsections depending on the type). These requirements can produce different results.