110.17 Servicing of equipment
Servicing is performed by qualified persons, following the manufacturer’s instructions and applicable standards, or as otherwise approved by the AHJ. Replacement parts come from the manufacturer, are designed by an engineer experienced with that equipment, or are approved by the AHJ.
110.18 Arcing parts
Parts that normally produce arcs, sparks, flames or molten metal are enclosed or separated and isolated from combustible material.
110.20–110.21 Reconditioned equipment and marking
Reconditioned equipment is permitted unless the NEC prohibits it for that equipment. Where listing is required, it is listed or field labeled as reconditioned. Equipment carries durable identification and its ratings; reconditioned equipment also shows who reconditioned it, the date, and that it was reconditioned.
110.22–110.23 Disconnects and current transformers
Each disconnecting means is legibly marked to show its purpose unless that is evident. Where more than one source exists, the marking also identifies the source unless the arrangement makes it evident. Unused current transformers associated with potentially energized circuits are short-circuited.
110.24 Available fault current
Service equipment at other than dwelling units is field marked with the available fault current and the date of the calculation. When a modification changes the available fault current, it is verified or recalculated and the marking updated.
110.25 Lockable disconnecting means
Where a disconnect must be lockable open, the locking provision stays in place with or without the lock installed.
Why it matters
Renovation work reuses existing equipment constantly. Ask who serviced it, whether the replacement parts are acceptable, whether the markings are still accurate, whether a new transformer, utility change or generator moved the fault current, and whether the disconnect can actually be locked open.
Where to show it
As applicable: the single-line diagram and panel schedules (source identification), equipment schedules noting reconditioned items, the fault-current table or study with its date, and specifications for labels and lockable disconnects.
Field tip
When equipment has been modified, do not assume the old label still tells the truth. Verify the condition, source identification, servicing history and available fault current before relying on existing markings. In Miami-Dade this is exactly the evidence an electrical building recertification asks for. Next: #025 — NEC 110.26 Working Space.
Code basis
NEC 2026 Article 110.17–110.25 education from the owner-provided Daily Code Talk. Confirm the locally adopted NEC edition and amendments. Not a fault-current study or a reconditioning approval.