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

What voltage ceiling appears in the CSLB's definition of the C-7 Low Voltage Systems classification?

• a.120 volts
• b.91 volts✓
• c.50 volts
• d.600 volts

The C-7 definition covers energy-limited communication and low voltage systems that do not exceed 91 volts. Fifty volts is a Cal/OSHA work-practice threshold, not the license limit; 120 volts is ordinary branch-circuit voltage; and 600 volts is the dividing line used in some safety rules, not the C-7 scope.Cal. Code Regs. tit. 16 §832.07 (C-7 classification, CSLB)

Which system does the CSLB's C-7 classification name as included work?

• a.Low voltage landscape lighting✓
• b.Fire sprinkler piping
• c.Fire alarm notification circuits
• d.277-volt lighting branch circuits

The C-7 definition lists low voltage landscape lighting among its examples. Fire alarm systems are specifically excluded from C-7; 277-volt lighting circuits exceed the 91-volt limit and are electrical work; and sprinkler piping is fire protection work.Cal. Code Regs. tit. 16 §832.07 (C-7 classification, CSLB)

A company installs and services fire alarm systems as a fire alarm company operator. Which agency must license it, according to the CSLB?

• a.The Contractors State License Board✓
• b.No license is needed for alarm work
• c.The Bureau of Security and Investigative Services
• d.The Federal Communications Commission

The CSLB states that fire alarm company operators must be licensed by the CSLB. The Bureau of Security and Investigative Services licenses security alarm company operators, the FCC regulates radio services rather than contractors, and fire alarm work is not license-exempt.CSLB, Before Applying for the Examination (licensing exemptions)

A person's only business is installing satellite antenna systems on homes. What does the CSLB say about licensing for that activity?

• a.Exempt, but must register with a state bureau✓
• b.Needs neither a license nor a registration
• c.Must hold a C-7 license for this work
• d.Must hold a C-10 license because antennas are electrical

The CSLB lists persons whose only activity is installing satellite antenna systems on residential structures as exempt, but they must be registered with the Bureau of Electronic and Appliance Repair. A C-7 or C-10 license is not required for that narrow activity, and registration is still required.CSLB, Before Applying for the Examination (licensing exemptions)

Under Cal/OSHA's Low-Voltage Electrical Safety Orders, what limits apply to the source of a Class 1 power-limited circuit?

• a.Not over 30 volts and 1,000 volt-amperes✓
• b.Not more than 91 volts and 100 volt-amperes
• c.Not more than 600 volts, power unlimited
• d.Not more than 50 volts and 500 volt-amperes

A Class 1 power-limited circuit is supplied from a source rated not more than 30 volts and 1,000 volt-amperes. Ninety-one volts is the C-7 license limit; 600 volts with unlimited power describes Class 1 remote-control and signaling circuits; and 50 volts with 500 VA is not a class limit in the safety orders.Cal. Code Regs. tit. 8 §2585.1 (Class 1, 2 and 3 circuits)

Using the federal criterion's rule of thumb, about how large should a telecommunications room be to serve 10,000 square feet?

• a.About 1,100 square feet
• b.About 11 square feet
• c.Approximately 110 square feet✓
• d.About 500 square feet

The criterion sizes rooms at about 1.1 percent of the area served, so 10,000 × 0.011 = 110 square feet — its example is a 10-by-11-foot room. Eleven square feet uses 0.11 percent, 1,100 square feet uses 11 percent, and 500 square feet matches no rule in the criterion.UFC 3-580-01 (2024), para. 2-3.1.2.2 (telecommunications room sizing)

An architect shows a lay-in suspended ceiling in the new telecommunications room. What does the federal criterion say?

• a.A suspended ceiling is required to hide cable tray
• b.A suspended ceiling is not to be installed in the room✓
• c.A suspended ceiling is required for fire separation
• d.A suspended ceiling is allowed if it is plenum rated

The criterion says not to install suspended ceilings in telecommunications spaces, keeping overhead tray and ladder rack accessible. It is not required to hide tray, a plenum rating does not change the rule, and fire separation comes from rated walls and firestopping, not a lay-in ceiling.UFC 3-580-01 (2024), para. 2-3.1.2.3 (floors, walls, ceilings)

What backboards does the federal criterion require in a telecommunications room?

• a.Pegboard on the wall behind the rack
• b.Fire-retardant plywood, two walls✓
• c.Painted drywall on one wall
• d.Untreated plywood on every wall

Backboards must be fire-retardant-treated wood bearing the manufacturer's stamp, covering at least two adjacent walls. Drywall is not a backboard, untreated plywood lacks the fire-retardant treatment, and pegboard is not specified for mounting communications equipment.UFC 3-580-01 (2024), para. 2-3.1.5.1 (plywood backboards)

Under the federal criterion, which situation does NOT allow non-continuous supports (J-hooks) as the pathway?

• a.A run over 50 feet through supports✓
• b.A short run from tray to a single outlet
• c.A run supported from building structure
• d.A run of 12 cables in a dry ceiling

The criterion does not permit non-continuous supports in spaces over 50 feet total length through the support system. A short drop from tray, a light load within the 20-cable limit, and supports attached to structure are all consistent with its rules.UFC 3-580-01 (2024), para. 2-3.2.3.3 (non-continuous cable supports)

What conduit fill does the federal criterion use as its optimal design ratio?

• a.25 percent
• b.40 percent✓
• c.80 percent
• d.60 percent

The criterion uses an optimal conduit fill ratio of 40 percent and never more than 50 percent. Twenty-five percent is its initial design fill for cable tray, and 60 and 80 percent both exceed the 50 percent maximum.UFC 3-580-01 (2024), para. 2-3.2.3.2 (conduit)

Communications cable and power conductors share a pole. Where does the safety order place the communications cable, where practicable?

• a.On the same crossarm as the power
• b.Below the power conductors✓
• c.Above the power conductors
• d.Inside the power conductors' conduit

Where practicable, communications wires and cables on poles are located below the electric light or power conductors, and they may not be attached to a crossarm that carries power conductors. Placing them above power, on the power crossarm, or in a power conduit all contradict the rule.Cal. Code Regs. tit. 8 §2587.3 (conductor location)

Which installation does the California Electrical Code state it does NOT cover?

• a.A contractor's data cabling in an office building
• b.Optical fiber cable in a hospital
• c.Class 2 thermostat wiring in a house
• d.A phone company's own equipment in its own utility vault✓

The code does not cover communications equipment under the exclusive control of communications utilities, located outdoors or in spaces used only for such installations. Premises data cabling, optical fiber cable and Class 2 wiring in buildings are within its scope, which includes signaling and communications conductors and optical fiber cables.California Electrical Code 2025, Art. 90.2(D) (installations not covered)

A raised-floor computer room needs relocatable floor boxes fed by flexible metal conduit. What length limit does the federal criterion set for each flexible run?

• a.100 feet
• b.50 feet
• c.6 feet
• d.20 feet✓

Flexible metal conduit is allowed only for relocatable floor boxes in a raised floor, limited to 20 feet per run. Six feet is not the stated limit, 50 feet is the J-hook run limit, and 100 feet is the maximum conduit run between pull boxes.UFC 3-580-01 (2024), para. 2-3.2.3.2 (flexible metal conduit)

A unique wall penetration has no UL-tested firestop system available from any manufacturer. What does the federal firestopping specification require?

• a.A fire-rated paint over the opening
• b.Any caulk the installer has on hand
• c.The manufacturer's engineering judgment✓
• d.Leaving the penetration open until a system is tested

Where no tested system is available, the specification requires the manufacturer's engineering judgment, derived from similar tested designs and submitted for approval before installation. Random caulk is not a tested or engineered system, an open penetration defeats the wall's rating, and paint does not firestop an opening.UFGS 07 84 00, Firestopping (submittals)

The plumbing designer routes a domestic water line over the new data racks. What does the federal criterion say?

• a.Piping is fine if a ceiling tile is below it
• b.Piping must not be routed over racks or cabinets✓
• c.Piping may run over racks if it is insulated
• d.Piping is fine if the racks are grounded

Utility piping must not be routed over communications racks, cabinets or electrical panels; where unavoidable, special protection such as double-wall piping or drip pans with leak detection is required. Insulation, a ceiling tile or grounding the racks do not keep a leak off the equipment.UFC 3-580-01 (2024), para. 2-3.1.3.4 (room climate control)

Predictive RF design software is not available for an office Wi-Fi layout. What coverage radius per access point does the federal criterion allow?

• a.No more than 10 feet
• b.No more than 43 feet✓
• c.No more than 100 meters
• d.No more than 295 feet

Without predictive software, the criterion limits each access point's coverage radius to 43 feet (13 meters) in an office environment. One hundred meters is a cable reach for PoE and HDBaseT, 10 feet is far too small, and 295 feet is the horizontal cable limit.UFC 3-580-01 (2024), para. 2-3.5.3 (wireless access points)

Metal-sheathed aerial telephone cable enters a building where it could contact power conductors. What does the safety order require for the sheath?

• a.Remove the sheath inside the building
• b.Bond it to the lightning rod down conductor
• c.Ground it, or use an insulating joint at entry✓
• d.Leave it floating so it cannot carry current

The metal sheath of aerial cables exposed to power contact must be grounded, or interrupted close to the building entrance by an insulating joint or equivalent device. A floating sheath can carry a fault into the building, lightning conductors must stay 6 feet away from communications cable, and stripping the sheath is not the required protection.Cal. Code Regs. tit. 8 §2587.5 (grounding)

A new building has two elevators. How many communications work area outlets does the federal criterion call for in the elevator machine room?

• a.Four, two per elevator
• b.One for the whole machine room
• c.None; elevators use their own phones
• d.At least two, one per elevator✓

The criterion provides a minimum of one work area outlet in the elevator machine room for each elevator, so two elevators need at least two. One for the room falls short, providing none ignores the requirement, and four is more than the stated minimum.UFC 3-580-01 (2024), para. 2-3.4.4.5 (elevators)