Impairments, Deficiencies and Troubleshooting
NFPA 72-2022 §10.3, §10.21 and Ch. 12 · NFPA 72-2022 §14.2.2 and §14.4.2 · NFPA 72-2022 Table 14.4.3.2 and Ch. 17 · NFPA 70-2020 Art. 760 and Ch. 9 Table 8 · Outline tasks 2.2.2
What NICET expects at Level II (task 2.2.2)
Task 2.2.2, Correct impairments/deficiencies, sits inside Maintenance (25–35% of the 110-question exam). At Level I you recognized a fault and replaced a device under supervision. At Level II you are the person sent on the trouble call: you read the panel history, decide which circuit and which fault type you are chasing, measure, split the circuit, repair it with listed and compatible parts, decide which testing the repair triggers, and make sure the right people are told. Expect two- and three-step scenarios (a symptom, a measurement, a decision) plus short calculations: Ohm's law, wire resistance from NEC Chapter 9 Table 8, and a percentage of devices. Only NFPA 72-2022, NFPA 70-2020, and IBC-2021 are allowed in the test center, so NFPA 101 and IFC rules show up mainly as traps.
Impairments, deficiencies, and observations
| Situation | What NFPA 72-2022 requires | Section |
|---|---|---|
| System or part of it is impaired | Notify the owner or designated representative | §10.21.1 |
| Impairment record | Kept by the owner or representative for 1 year from the date the impairment is corrected | §10.21.2 |
| Required monitoring terminated | The supervising station reports it to the AHJ | §10.21.3 |
| Out of service more than 8 hours | The service provider reports it to the AHJ | §10.21.4 |
| Mitigating measures (fire watch, patrols) | Implemented for the impairment period where the AHJ requires them | §10.21.5 |
| Impairment ends | Owner or representative and the AHJ are notified | §10.21.6 |
| Automatic function removed from service, no manual or other compensating means | That portion of the system is impaired | §14.2.2.2 |
| Deficiency not corrected at the end of the visit; equipment in a recall program | Owner informed in writing (within 24 h for the deficiency) | §14.2.2.3 |
| Observation (suggested improvement) | May be communicated; the owner need not act | §14.2.2.4 |
Trap: the 4 hours in 24 hours fire-watch trigger comes from NFPA 101 (and codes that adopt it), not from NFPA 72. The NFPA 72 number is 8 hours, and it is a report to the AHJ by the service provider. Mitigation is whatever the AHJ requires.
Troubleshooting method and fault signatures
- Read the panel and its history: signal type, point, and time pattern (the same hour every day points to HVAC or a schedule).
- Notify the owner and the supervising station before you disable or lift anything.
- Lift the circuit at the panel before you use an ohmmeter or megohmmeter. Measure conductor to conductor, each conductor to ground, and stray voltage.
- Split the circuit: if the trouble stays, the fault is in the part still connected; if it clears, the fault is in the part you removed.
- Repair with listed, compatible parts, perform the reacceptance testing, restore every point, notify, and document.
| Symptom | Usual cause | Key point |
|---|---|---|
| OL between conductors | Open conductor, loose terminal, missing EOL | Class B loses everything beyond the open; Class A keeps operating |
| 0 Ω between conductors | Short | Conventional IDC reads alarm; NAC and SLC read trouble |
| Ground-fault trouble | Conductor touching metal or water | Annunciated within 200 s (§12.6.1); split the circuit |
| More than 1 V stray voltage | Cross-connection or induced voltage from power wiring | Table 14.4.3.2 (conductors, metallic) |
| Duplicate address, wrong type | Two devices share an address, or the wrong device was installed | Readdress and update the database, labels, and records |
| Intermittent far-end troubles on an SLC | Wire length or capacitance beyond the manufacturer's limit, noise, high-resistance joint | Compare with the manufacturer's published limits |
| Low voltage at the last appliance | Voltage drop or a bad splice | Compare measured drop with calculated drop |
| Loop resistance far above the calculated value | Smaller wire than drawn, or a bad joint | Short the far end, divide the reading by 2 × length to get Ω per 1000 ft, and compare with Table 8 |
| Ground indication on one conductor only | Control unit ground detection defective | Item 3(3): a ground on any conductor must be indicated |
| Waterflow alarm later than 90 s | Retard set too long | Reduce the retard, retest through the inspector's test connection (Ch. 17) |
| Alarm verification longer than 60 s | Setting above the limit (§23.8.5.4) | Reduce it and verify the delay and response (item 26(1)) |
| Annunciator lights the wrong point | Mapping or label error | Item 11: correct, retest each point, update records |
| DACT on one path only (installed after the 2013 edition) | Missing second means of transmission | Item 4(2); the exception is for older DACTs on a supervised line |
Class A and Class X pathways survive a single open; Class X with isolators also survives a short. Class B does not. Two opens in a Class A loop strand the devices between the breaks. The EOL goes at the last device, not in the panel, and a T-tap on a Class B IDC leaves the branch unsupervised.
Calculations to do quickly
- Ohm's law: R = V ÷ I. Voltage drop = I × round-trip resistance.
- Table 8, copper, uncoated, solid (Ω per 1000 ft): 18 AWG 7.77 · 16 AWG 4.89 · 14 AWG 3.07 · 12 AWG 1.93 · 10 AWG 1.21. Round trip = 2 × one-way length.
- Distance to a hard short (one way) = measured Ω ÷ (2 × Ω per ft).
- Wire size from a loop reading (far end shorted): Ω per 1000 ft = reading ÷ (2 × one-way kft); match it to Table 8.
- Circuit integrity test: open a connection at not less than 10% of devices on each circuit; round up.
- Resistor bands: orange-white-red = 3.9 kΩ; yellow-violet-red = 4.7 kΩ; yellow-violet-orange = 47 kΩ.
- Heat detector rating: maximum expected ceiling temperature + 20°F, then pick the class.
Unwanted alarms: fix the cause without reducing protection
| Cause | Correction |
|---|---|
| Dust, dirt, drift (analog value far above neighbors) | Clean, verify sensitivity is in the listed and marked range, replace if not (§14.4.4.3) |
| Steam, cooking aerosols | Relocate or change detector type with designer and AHJ agreement |
| Air velocity above the detector's listing | Relocate, or use a model listed for the conditions (Ch. 17) |
| Electrical noise (VFDs) | Separate the wiring, use the specified cable, ground shields at the panel only |
Replacement, compatibility, and reacceptance
- §10.3: equipment must be listed for its purpose, and devices powered from an IDC or SLC must be compatible with the control unit. A listing on the head alone does not prove head, base, and panel compatibility.
- §14.4.2: test whatever you added, replaced, or changed. A like-for-like replacement needs only the replaced device tested (A.14.4.2). A site-specific software change needs 100% of what is affected plus 10% of the unaffected initiating devices (maximum 50), and a revised record of completion.
- If the repair changes what the system does, the drawings, device list, and point labels must change too.
- Batteries: replace a VRLA unit that deviates 30% (conductance) or 40% (resistance or impedance) from its baseline. The annex (A.14.4.3.2) adds that when one unit of a series string fails after 2 to 3 years, it is desirable to replace both so they float together; the exception is a unit that fails in the first year.
Communicating and documenting
Tell the owner before and after. Tell the supervising station before you test or disable and after you restore. Write down what you found, what you measured, what you changed, which points were disabled, and when each was restored. Put deficiencies you could not fix in writing to the owner within 24 hours.
Finding it in your printed books
- Index terms: Impairments, Deficiency, Observation, Reacceptance testing, Ground fault, Class A, Digital alarm communicator, Stray voltage.
- Tab §10.21, §10.3, §12.3, §12.6, §14.2.2, §14.4.2, Table 14.4.3.2, Table 17.6.2.1, and §26.6.4. The first digits of a section number are its chapter.
- In NFPA 70 tab Article 760 (760.41, 760.121, 760.136) and Chapter 9 Table 8. An asterisk (*) means Annex A explains the section (A.14.4.2).
Tip: when two answers both sound right, choose the one that fixes the cause, keeps the protection the design requires, and notifies the right people.
What to tab in your books
| Section | Why |
|---|---|
| NFPA 72 §10.21 | Impairments: owner, supervising station, AHJ at more than 8 h, mitigation per AHJ, end-of-impairment notice, 1-year record |
| NFPA 72 §10.3 | Equipment listed for purpose; compatibility of devices on IDC and SLC with the control unit |
| NFPA 72 §10.6 | Power supplies: primary branch circuit, secondary battery, charger |
| NFPA 72 §12.3 | Pathway classes A, B, X: behavior with open, ground, and short |
| NFPA 72 §12.6 | Monitoring for integrity: open and ground annunciated within 200 s |
| NFPA 72 §14.2.2 | Impairments, deficiencies (written notice within 24 h), recalls, observations |
| NFPA 72 §14.4.2 and A.14.4.2 | Reacceptance testing after added, deleted, or changed devices, hardware, and software |
| NFPA 72 Table 14.4.3.2 item 2 | Control unit functions after hardware repair |
| NFPA 72 Table 14.4.3.2 item 9 and A.14.4.3.2 | Batteries and charger tests, including the 13.26 V float check on 12 V VRLA; annex advice to replace both units of a failing series string |
| NFPA 72 Table 14.4.3.2 items 3(3), 4(2), 11, 26(1) | Ground detection, DACT two means of transmission, annunciators, alarm verification delay |
| NFPA 72 Table 14.4.3.2 item 15 | Conductors: stray voltage 1 V, ground, short, loop resistance, 10% open-connection test |
| NFPA 72 §14.4.4.3 | Smoke detector sensitivity: out of range means clean or replace |
| NFPA 72 §17.6.2 and Table 17.6.2.1 | Heat detector rating at least 20°F above maximum ceiling temperature; classes |
| NFPA 72 §17.7 | Smoke detector location and environment (air velocity, temperature, humidity) |
| NFPA 72 §26.6.4 | DACT: line seizure, two means of transmission, 4-minute trouble indication |
| NFPA 70 §760.41(B) and §760.121(B) | FACU branch circuit: red identification, no GFCI or AFCI, restricted access |
| NFPA 70 §760.136 | Separation of power-limited fire alarm conductors from power conductors |
| NFPA 70 Ch. 9 Table 8 | Conductor DC resistance per 1000 ft for troubleshooting calculations |
Chapter vocabulary
- Impairment
- A condition in which a system, a part of it, or a function is out of service.
- Deficiency
- A condition that must be corrected; if not corrected during the visit, the owner is told in writing within 24 hours.
- Observation
- A suggested improvement that is neither an impairment nor a deficiency; the owner need not act.
- Mitigating measures
- Steps during an impairment, such as a fire watch, that the AHJ may require.
- Reacceptance testing
- Testing required after devices, wiring, hardware, or software are added, deleted, or changed.
- Half-splitting
- Opening a circuit at a midpoint to learn which half holds the fault.
- Stray voltage
- Unwanted voltage between conductors or to ground, limited to 1 V ac/dc unless the manufacturer allows more.
- Hard short
- A direct, near-zero-ohm connection between two conductors.
- Round-trip resistance
- Resistance of the outgoing plus return conductors, used to calculate voltage drop.
- Voltage drop
- Loss of voltage along a conductor, equal to current times round-trip resistance.
- Duplicate address
- Two addressable devices on one SLC set to the same address.
- Fault isolator
- SLC device that isolates a shorted segment so the rest of the circuit keeps operating.
- Class A / X pathway
- Redundant pathway that tolerates a single open; Class X also tolerates a short.
- EOL resistor
- Resistor at the last device that lets the panel supervise a Class B circuit.
- Analog value
- Numeric reading a detector sends the panel; a value far above its neighbors suggests contamination.
- Unwanted alarm
- An alarm not caused by a potentially hazardous condition: malicious, nuisance, unintentional, or unknown.
- Line seizure
- DACT ability to take over a telephone line from other equipment to send a signal.
- Compatibility listing
- Manufacturer and listing laboratory approval of a specific device with a specific control unit.
- Fire watch
- Trained personnel patrolling a building whose fire alarm is out of service.
- Loop resistance test
- Measurement of a circuit pair with the far end shorted; the reading is compared with the manufacturer's limit and with the resistance calculated from the wire size and length.
- Retard (waterflow)
- Delay built into a waterflow switch to ride out pressure surges; the alarm must still be initiated within 90 seconds of the flow.
26 practice questions cover this chapter, each with an explanation and the code section. Get lifetime access or try the free practice exam.
More Level II study guides
- 10-week study plan
- Power, Loading and Circuits
- Detector and Notification Layout
- Control Functions, Interfaces and Commissioning
- Periodic Testing and Records
- Impairments, Deficiencies and Troubleshooting
- IBC 2021 and Building Context
- Work Plans, Contracts and Coordination
- Level II tabbing guide for your printed code books
- Strategy with printed code books
- Key numbers (NFPA 72 · NEC · OSHA)
- Formulas and conversions
- Fire alarm glossary for the NICET exams