Sign Here: The Duct Detector Nobody Tested
During a periodic inspection and test of a six-year-old system, the technician records four findings. (1) The two 12 Ah batteries, installed five years ago, accept a load test but deliver only about 6.8 Ah before reaching the manufacturer's end voltage; the original design calculation required 7.6 Ah. (2) A duct smoke detector serving a rooftop unit is located above a hard-lid ceiling with no access panel; it was not tested. (3) A supervisory trouble on the duct detector circuit appears only when the RTU fan runs. (4) All other initiating devices tested normally. The building is occupied, and the owner tells the technician to sign the inspection form, note the duct detector for next year, and not to worry about the battery because "it still holds a charge." Access for the duct detector would require after-hours work in a tenant suite.
1. Evaluate the battery finding. What is required?
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The battery has failed and must be replaced before the inspection is closed out.
- The design requirement is 7.6 Ah (24 h standby plus the alarm period, with the safety factor). The measured delivered capacity is 6.8 Ah - about 89% of the requirement and roughly 57% of the 12 Ah nameplate.
- The relevant question is not "does it hold a charge" but "will it carry the connected load for the full standby period and then operate the notification appliances." At 6.8 Ah it cannot; the system would lose secondary power before the end of the required standby time.
- Age matters independently. At five years the battery is at or past the typical replacement interval for this class of sealed lead-acid battery, and capacity will continue to fall.
- Actions: replace with the correctly sized battery, verify the charger is rated for it, re-run the load test, and record the measured capacity and the new battery's date code in the inspection record. Report the deficiency to the owner in writing with the correction date - this is a critical deficiency, not a housekeeping note.
2. The duct detector could not be tested and shows a fan-related supervisory trouble. How does this affect the inspection and the form?
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The inspection is incomplete, and the form must say so.
- A device that was not tested cannot be reported as tested. Signing the form as though the system was fully inspected would be a false attestation, regardless of the owner's request.
- The fan-related supervisory trouble is itself a finding: it points to a wiring or termination problem that appears under vibration or airflow (loose termination, a conductor pinched at the unit, or a device that drops offline when the fan starts). That must be investigated and corrected - a supervisory signal that comes and goes with equipment operation is exactly the kind of latent fault the periodic test exists to find.
- The missing access panel is a code/listing problem in its own right: the duct detector must be accessible for service and test. Installing a listed access panel is a required correction, not a convenience.
- On the form: list the untested device, the intermittent supervisory condition, and the missing access as deficiencies; state that the inspection of those items was not completed; give a correction date; and notify the owner in writing. Do not certify the system as fully functional.
3. What is the correct response to the owner's pressure and to the impaired condition of the system?
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- Refuse to sign an inaccurate form. Offer the accurate version instead: everything tested is documented as passing, everything not tested is documented as not tested with a correction date. This protects the owner, the technician, and the company.
- Treat the condition as an impairment. A duct detector that is untested and in trouble, plus a failed battery, means the system is not fully functional. The owner must be notified in writing; depending on the occupancy and the local requirements, the AHJ may need notification and a fire watch or other mitigation may be required until repairs are complete.
- Set a practical schedule. After-hours access is a scheduling issue, not a reason to defer; the access panel installation and the duct detector test are scheduled work with a firm date. The battery is corrected immediately - it does not require tenant access.
- Follow up. Re-test the untested device and the intermittent circuit after correction, and issue a supplemental report. The record must show a closed loop: deficiency → notification → correction → retest.
- Escalate internally if pressured. A written instruction from a client to omit a required test does not change the technician's obligation; document the request and the response in the job file.