The 2023 NEC pushed several 2020-era rules further. Surge protection, first mandatory for dwelling units in 2020, now extends to multifamily buildings, dormitories, guest rooms and suites, and nursing and assisted-living facilities; the devices must be Type 1 or Type 2, so a plug-in surge strip no longer satisfies the requirement anywhere it applies. GFCI protection was extended too, including new coverage for buffet-style serving areas. In a broader structural change, key definitions — like "transformer," which appears throughout the code — were formally added to Article 100 for the first time.

If your prep is still built on the 2020 code, this is exactly the gap that costs candidates points: the expanded surge protection scope and newer GFCI requirements are new material, not extensions of something you'd already recognize. The R-series is the newest, most current edition tested in the ICC electrical program, and it's the direction more jurisdictions are moving toward.

MCL's R-series prep is built exclusively on the 2023 NEC, so what you're studying is what's being tested today, not last cycle's rules.