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If end voltage must be at least 16 V, result in is:
Within device range for many appliances
Definition: Many 24 V appliances list 16-33 V; verify specific device listings.
Reducing drops is best done by:
Shorter runs or larger wire or distributed supplies
Definition: Drop is proportional to length and resistance; reduce either.
Two equal sound sources at 82 "dBA" combine to about:
85 "dBA"
Definition: Doubling equal sources adds roughly 3 dB.
A corridor 10 feet wide commonly uses spot smoke detectors spaced about:
41 ft
Definition: Corridor channeling permits about forty one feet on center; confirm with device listings.
Battery standby 0.35 A for 24 h equals:
4.2 Ah
Definition: 0.35 times 24 equals 8.4 Ah - wait, check math in next item.
Correction to: 0.35 A for 24 h actually equals:
8.4 Ah
Definition: 0.35 times 24 equals 8.4 amp hours; use this value for sizing.
Add 2.5 A alarm for 5 minutes equals how many Ah?
0.21 Ah
Definition: 5 minutes is 1 slash 12 hour. 2.5 times 1 slash 12 equals 0.208 Ah, rounded to 0.21.
Total from and before margin is:
8.61 Ah
Definition: 8.4 plus 0.21 equals 8.61 Ah.
Applying 20 percent margin to 8.61 Ah requires at least:
10.3 Ah
Definition: 8.61 times 1.2 is about 10.33 Ah.
Speaker taps totaling 56 W on a 50 W amp indicates:
Overload risk and potential clipping
Definition: Exceeding rated watts risks clipping and poor intelligibility.
Upsizing from 18 "AWG" to 14 "AWG":
Decreases resistance and drop
Definition: Thicker wire lowers resistance per foot.
Two 12 V 7 Ah batteries in series provide:
24 V 7 Ah
Definition: Series adds voltage; amp hours stay the same.
If corridor detectors are too close to supply diffusers, likely effect is:
Delayed or no alarm due to dilution
Definition: Air currents can push smoke away from the sensor head.
A heat detector in a 120 F ambient that is rated 135 F:
May false alarm or desensitize; select a higher rating
Definition: Choose ratings at least 25 F above the highest expected ambient.
Beam detector alignment should be confirmed with:
Manufacturer’s alignment aids and obscuration tests
Definition: Follow the listed alignment and test procedures.
A "NAC" wire loop of 4 ohms with 2.0 A load drops:
8.0 V
Definition: 2.0 times 4 equals 8.0 volts drop.
End voltage in from a 24 V panel is:
16 V
Definition: 24 minus 8 equals 16 volts at the end.
If device minimum is 16 V, the result is:
Meets the minimum threshold
Definition: At the threshold; consider margin for battery and cold conditions.
A missing device on the "SLC" after ceiling work suggests:
Open wiring or removed/failed device
Definition: Construction can damage cabling or remove devices; inspect the segment.
Unsynced strobes from two supplies in one room require:
A listed synchronization method or compatible supplies
Definition: Sync when visible together to avoid confusion.
Duct detector not responding to smoke likely means:
Reversed or blocked sampling tube or inadequate pressure
Definition: Verify tube direction and differential pressure.
Door holders stay energized during alarm likely indicates:
Unsupervised power feed not dropped by alarm
Definition: Door holders should release on alarm or power loss.
Elevator recall not initiating on lobby smoke is commonly due to:
Detector not mapped to recall logic or wrong input type
Definition: Ensure programming matches the sequence matrix.
Frequent false alarms near showers usually mean:
Steam adversely affecting nearby smoke detectors
Definition: Relocate or switch technology to reduce nuisance.
A ground fault that appears intermittently is often caused by:
Moisture intrusion or damaged insulation contacting ground
Definition: Moisture or insulation cuts can intermittently touch ground.