Connecticut Low Voltage Practice flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's Law

V = I × R. Voltage equals current times resistance. Used to calculate voltage drop, current draw, and resistance in low-voltage circuits.

Power formula

P = V × I = I²R = V²/R. Determines wattage, heat, and power supply sizing for low-voltage devices.

Series circuit

Components connected end-to-end; current is constant, voltage divides. Total resistance is the sum of individual resistances.

Parallel circuit

Components connected across the same voltage; voltage is constant, current divides. Total resistance is less than the smallest branch.

Voltage drop formula

VD = 2 × K × I × L / CM for single-phase. K=12.9 copper, 21.2 aluminum. Keep branch drop ≤3%, total ≤5%.

Class 2 circuit

NEC Article 725 power-limited circuit up to 100 VA and 30 V. Used for low-voltage control, signaling, and communications.

Plenum-rated cable

CMP cable listed for air-handling spaces. Required by NEC 300.22(C) in ducts and plenums to limit smoke and flame spread.

Bend radius

Minimum curve radius for cable; typically 4× diameter for UTP, 10× for coax/fiber. Exceeding causes attenuation and signal loss.

Cable separation

Low-voltage cables must be at least 2 in. (50 mm) from power conductors, or separated by a barrier, per NEC 725.136 and 800.133.

NEC Article 725

Covers Class 1, 2, and 3 remote-control, signaling, and power-limited circuits. Defines wiring methods and separation requirements.

NEC Article 760

Covers fire alarm systems. Defines NPLFA and PLFA circuits and requires listed FPL, FPLR, or FPLP cable.

NEC Article 800

Covers communications circuits (telephone, data). Requires separation from power and grounding/bonding of cable shields.

NEC Article 820

Covers community antenna television (CATV) and radio distribution systems. Requires bonding of coaxial cable shield to ground.

Connecticut L-1 license

Low-voltage electrical license allowing installation and service of fire alarm, security, data, and communications systems; no line-voltage work.

Connecticut CEU requirement

Licensed electricians must complete 7 hours of continuing education annually, including code update and safety hours. Verify with DCP.

Connecticut fire alarm permit

Required for fire alarm installation; issued by local AHJ under Connecticut Fire Safety Code and NFPA 72.

Smoke detector spacing

NFPA 72: 30 ft (9.1 m) on smooth ceilings up to 10 ft high; use 0.7× ceiling height for higher ceilings, minimum 30 ft.

NAC voltage drop

Notification appliance circuit voltage drop must not exceed 10% of rated voltage at the last appliance. Calculate using device current draw.

Class A vs Class B

Class A fire alarm circuit returns to panel and survives one open. Class B does not return; an open disables downstream devices.

Fire alarm battery sizing

Calculate standby (24 h) plus alarm (5 min) load per NFPA 72; add 20% derating for battery aging.

Access control fail-safe

Lock releases on power loss. Required for egress doors per NFPA 101; must interface with fire alarm for release on alarm.

PoE standards

IEEE 802.3af (15.4 W), 802.3at (30 W), 802.3bt (60/90 W). Used for IP cameras, access control, and VoIP phones over UTP.

Wiegand protocol

Access control communication standard using 26-bit or 34-bit format. Cable distance limited to 500 ft (150 m) with 22 AWG.

CCTV storage calculation

GB = bitrate (Mbps) × 3600 × hours × days / 8 / 1000. Determines hard drive size for video retention.

TIA-568 channel length

Maximum 100 m (328 ft) total: 90 m horizontal cable plus 10 m patch cords. Applies to twisted-pair Ethernet.

Fiber loss budget

Sum of connector loss (0.75 dB each), splice loss (0.3 dB), and fiber attenuation (0.35 dB/km SM; 3.5 dB/km OM). Must be below link budget.

HDBaseT

Audio/video extension standard over Cat cable up to 100 m. Transmits HDMI, Ethernet, power, and control.

TIA-607 bonding

Requires telecommunications bonding backbone (TBB) and grounding busbar (TGB) bonded to service ground with minimum 6 AWG copper.

Ground resistance

NEC 250.53 requires ≤25 ohms for a single electrode; add a second if higher. Telecom ground typically ≤5 ohms.

Lockout/tagout

OSHA 1910.147 procedure to isolate energy before work. Verify absence of voltage with a meter before touching conductors.

Connecticut contractor bond

Surety bond required for electrical contractor registration in Connecticut; amount varies by license type. Verify with DCP.

Division 27 and 28

MasterFormat divisions for Communications (27) and Electronic Safety and Security (28). Define low-voltage scope in construction documents.