T-Taps, Shared Raceway, and a Passed Rough-In
During a site walk on a six-story, 180,000 sq ft speculative office fit-out, you find the following on the fire alarm: the signaling line circuit is installed as a single Class B trunk with T-taps serving each tenant floor, although the sealed drawings specify Class A SLC. On two floors the SLC and notification circuits share a 4 in. EMT raceway with 277 V lighting conductors, with no barrier. The SLC shield drain wire is terminated on the ground bar at both the panel and the last device. Three splices are wire-nutted in junction boxes that now sit above a fully finished hard-lid corridor ceiling. The electrical rough-in inspection has passed, and the GC wants a substantial completion sign-off for the floors this week.
1. List the deficiencies in order of risk and cite the governing requirement for each.
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Shared raceway with 277 V lighting - highest risk. Power-limited fire alarm conductors cannot occupy the same raceway, box, or enclosure as electric light or power conductors (NEC Art. 760 separation rules, and the panel's power-limited listing). This is a shock and fault hazard, an insulation problem, and an EMI source; as installed the circuit is arguably no longer power-limited. It must be physically separated, not "fixed" with a field-installed barrier absent the designer's approval and the AHJ's acceptance.
Class B trunk with T-taps where the sealed design shows Class A. T-taps are permitted on Class B addressable circuits, so this is not a standard violation - it is a design-conformance failure. A single open still takes out every tap downstream, which is exactly what the Class A design was bought to prevent. Red-tag until the designer accepts the deviation in writing.
Wire-nut splices in boxes above a hard-lid ceiling. Junction boxes must remain accessible (NEC 314.29).
Shield drain grounded at both ends. Ground loop, nuisance ground faults; bond at one end per the manufacturer.
2. The GC says the electrical inspection passed and wants you to accept the floors. What do you do?
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A passed rough-in is not a fire alarm acceptance test, and it does not cure a separation defect or a design deviation. Do not sign.
Issue a written deficiency report - photographs, floor, grid reference, and quantity for every shared-raceway segment, every T-tap, and every inaccessible box - to the GC and the designer of record. Notify the AHJ in writing about the shared raceway if the space is or will be occupied; that condition is a life-safety and electrical hazard, not a punch-list item.
Then set the correction path: the designer issues a revised detail or the contractor separates the circuits; splices get accessible boxes or the ceiling becomes accessible; shield grounding is corrected; affected SLC segments are re-tested after repair. Only after that do you schedule the acceptance test with the AHJ present, and only the AHJ's witness closes the item. Signing this week would make you the author of a certification you know to be false.