CSLB C-7 Low Voltage Systems (Trade Exam) — All Questions

A link passes a simple continuity check but fails at high data rates. A split pair is suspected. Which instrument will reveal it?

• a.A light source and power meter
• b.A certification tester✓
• c.A continuity tester, run a second time
• d.A tone generator and probe

A split pair has correct pin-to-pin continuity, so only a certification tester measuring NEXT and the other performance parameters reveals it. A tone and probe identifies cables, repeating a continuity test gives the same misleading pass, and a light source and meter test fiber, not copper.UFGS 27 10 00 (2025), para. 3.11.1.3 (performance tests)

A link failed crosstalk after a technician re-terminated a jack. The pairs are untwisted about 1-1/2 inches at the jack. What is the fix?

• a.Replace the patch cord at the switch
• b.Add a longer jumper to the outlet
• c.Re-terminate with ≤1/2 in untwist✓
• d.Lower the switch port speed permanently

The specification limits untwist to 1/2 inch at the termination to keep cable geometry; 1-1/2 inches degrades crosstalk performance, so the jack is re-terminated correctly. A new patch cord or a longer jumper does not fix the jack, and lowering speed hides the defect rather than repairing it.UFGS 27 10 00 (2025), para. 3.4.2 (horizontal cable)

High-power PoE cameras on a bundle of 60 cables show rising errors in summer. What change addresses the cause?

• a.Wrap the bundle in insulation to stabilize it
• b.Unbundle the cables into loose basket tray✓
• c.Add more cable ties to tighten the bundle
• d.Replace the PoE switch with a faster one

Bundles heat under PoE; the criterion cites guidance that bundles should not exceed 24 cables and notes that unbundled cable in wire basket gets enough airflow, and cables may not exceed their temperature ratings. Tighter ties and insulation trap more heat, and a faster switch does not cool the cable.UFC 3-580-01 (2024), para. 2-3.3.5 (bundling)

A protector module on an aerial telephone circuit entering a building has failed after a storm. What is the correct repair?

• a.Replace it with a listed module✓
• b.Bypass it with a jumper wire
• c.Remove it so the line works without it
• d.Leave it failed until the next storm

A listed primary protector is required on each circuit run partly or entirely in aerial cable not confined within a block, so a failed module is replaced, not removed. Removing or jumpering it leaves the circuit unprotected, and waiting exposes the building to the next surge.Cal. Code Regs. tit. 8 §2587.2 (protective devices)

An outdoor camera's image is sharp by day but blurry at night. What is the most likely cause?

• a.The cable is Category 6A instead of 6
• b.Focus set in daylight✓
• c.The camera is set to 15 frames per second
• d.The camera is PoE powered

The criterion advises setting focus in low light with an auto-iris lens, because the iris opens at night and a daylight focus no longer holds. Frame rate, cable category and PoE power do not change optical focus.UFC 4-021-02 (2025), para. 5-2.3 (outdoor cameras)

A building automation system shows a room at 78°F while a calibrated thermometer reads 74°F. Which check from the federal controls specification addresses this?

• a.A Category 6A certification test
• b.A sensor accuracy check✓
• c.A BACnet broadcast management test
• d.An actuator full-stroke check

The specification includes a one-point accuracy check of each sensor; a 4-degree error calls for recalibrating or replacing the sensor. An actuator stroke check tests outputs, BBMD settings affect IP communication, and cable certification does not test sensor accuracy.UFGS 23 09 00, Instrumentation and Control for HVAC (performance verification)

Paging speaker conductors were pulled into a conduit with power-supply conductors, and the insulation of the speaker wire is lower-rated than the power wiring. What does the safety order require?

• a.A label on the conduit
• b.A 6-foot separation inside the conduit
• c.Nothing; sound wiring is exempt
• d.Equal insulation or a metal sheath✓

Conductors of different systems grouped in the same conduit must be insulated at least equivalent to the power-supply conductors, unless separated by a lead sheath or other continuous metallic covering. Sound wiring is not exempt, a label changes nothing electrically, and a 6-foot separation inside a conduit is impossible.Cal. Code Regs. tit. 8 §2564.6 (grouping of conductors)