NEC 240.86 / high-rise office Specification
What it means on the job
The high-rise commercial office specification explicitly prohibits series rating of overcurrent protective devices. All existing panels being re-utilized must use fully rated breakers — meaning each individual breaker must have an interrupting rating equal to or exceeding the available fault current at the panel (22kAIC in this case). Series rating is prohibited because in a multi-tenant high-rise, a fault that exceeds a branch breaker's interrupting rating could cause catastrophic breaker failure, arc flash, and damage to adjacent tenants' electrical systems. The branch breaker must be replaced with one rated at minimum 22kAIC.
Tested in 2 CraftIQ puzzles
- whats-wronghigh-rise office Office TI: Voltage Drop on Branch Circuit
- code-checkhigh-rise office Office TI: Series-Rated Breaker in Existing Panel
Related NEC sections
NEC 210.8(B)(7)
All 125V, 15A and 20A receptacles installed within 6 feet of a sink edge in commercial occupancies require GFCI protection. Break room sinks in commercial offices are treated the same as kitchen sinks for GFCI purposes.
NEC 230.24(B)
Service drop conductors over areas accessible to vehicular traffic must maintain a minimum clearance of 18 feet. Over residential driveways, the minimum is 12 feet. 8 feet is dangerously low.
NEC 230.95
NEC 230.95 requires ground-fault protection for equipment (GFPE) on services rated 1,000A or more at 480V. In a high-rise electrical riser, a ground fault without GFPE can cause an arcing fault that escalates into a fire within the riser shaft, potentially disabling power to multiple floors before being detected.
NEC 250.102
Flexible metal conduit in this size/length is not a reliable ground path; an equipment bonding jumper or an EGC must be run to bond the motor.
NEC 250.118 / 250.122 / 406.4(C)
Even though UF cable includes a grounding conductor, if individual conductors are run in conduit underground, an equipment grounding conductor of a recognized type must be included and sized with the circuit so the receptacle has an effective ground-fault current path.
NEC 250.118 / 410.44
Suspended ceiling support wires and grid members are not listed as equipment grounding conductors. A separate equipment grounding conductor or grounding path must be provided for all lighting fixtures.
CraftIQ explanations are original educational commentary written in trade language and verified against the cited standards. Always confirm requirements against the code edition adopted by your jurisdiction — this is training material, not a substitute for the code book or your AHJ.