Service Fundamentals: One Service per Building, the Disconnect, and the 2026 Outdoor Rule
Article 230 is the most-cited article on the Residential Wireman exam (16 of 80 items sit in this subject area) and it carries the single most important 2026 change for houses. Learn the structure: Article 230 runs in the same order the power does — overhead/underground conductors → service-entrance conductors → service equipment → disconnect → overcurrent protection.
NFPA 70 National Electrical Code, 2026 edition · Reviewed 2026-09-19
Article 230 is the most-cited article on the Residential Wireman exam (16 of 80 items sit in this subject area) and it carries the single most important 2026 change for houses. Learn the structure: Article 230 runs in the same order the power does — overhead/underground conductors → service-entrance conductors → service equipment → disconnect → overcurrent protection.
1. Vocabulary that the questions hinge on (Article 100)
- Service conductors — from the service point to the service disconnecting means.
- Service drop — the utility's overhead conductors to the service point. Overhead service conductors — the premises overhead conductors from the service point to the first point of connection to the service-entrance conductors. Same split underground: service lateral (utility) vs underground service conductors (premises).
- Service-entrance conductors — from the service point (or the terminal of the overhead / underground service conductors) to the service disconnect.
- Service equipment — the disconnect(s), overcurrent device(s) and accessories intended to be the main control and cutoff of the supply.
This is where the public part ends.
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