Case study · Hotel / Hospitality

Failing benchmark to
first-pass AHJ approval

AC Hotel Ann Arbor, a 7-floor hotel in Ann Arbor, Michigan, failed its public-safety benchmark grid test — legally triggering an ERCES. WZC took it to full code coverage, approved on the first inspection.

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First-pass AHJ approval7-floor hotel · 81,706 sq ftZero punchlist items

The project

Engineered to passthe first inspection

Benchmark: failed grid testAcceptance: first-pass approval

When AC Hotel Ann Arbor failed its public-safety benchmark grid test, the failure legally triggered an ERCES requirement. WZC ran the full process from there: predictive iBwave design and direct fire-marshal coordination, so the system on paper was the system the AHJ expected to see.

The installed system is a COMBA CriticalPoint Class A BDA feeding 54 ceiling dome antennas across 81,706 sq ft, backed by a 33.9-hour LiFePO4 battery system.

The acceptance grid test proved 95% general and 99% critical-area coverage with margin — earning first-pass AHJ approval with zero punchlist items.

All case studies
Technician installing an antenna on a building rooftop at sunset
COMBA CriticalPoint Class A BDA — antenna installation
0Ceiling dome antennas
81,706Sq ft covered
0General coverage
0Critical-area coverage
33.9hrBattery backup
0Punchlist items
  • Predictive iBwave design with fire-marshal coordination
  • COMBA CriticalPoint Class A BDA, 54 ceiling dome antennas
  • 33.9-hour LiFePO4 battery backup system
  • Acceptance grid test passed with margin — zero punchlist

Results

From failed benchmark to margin above code

0%25%50%75%100%GENERAL MIN 95%CRITICAL MIN 99%BENCHMARK GRID TESTFAIL — BELOW CODE, ERCES TRIGGEREDACCEPTANCE — GENERAL AREAS95%ACCEPTANCE — CRITICAL AREAS99%FIRST-PASS AHJ APPROVAL · 0 PUNCHLIST ITEMS · 54 DOME ANTENNAS · 33.9-HR BATTERY BACKUP
Acceptance grid-test results at AC Hotel Ann Arbor — 95% general and 99% critical-area coverage across 81,706 sq ft, approved on the first inspection.
Failed benchmark / critical minimumGeneral-area acceptance coverageCritical-area acceptance coverageIFC 510 general minimum

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