California Low Voltage Practice cheat sheet

NFPA 70E establishes arc flash PPE categories; Category 0 requires untreated cotton, Category 4 requires a 40 cal/cm² arc-rated suit.

OSHA 1910.147 requires lockout/tagout for energy sources; verify zero energy state with a tester rated for the circuit voltage.

NEC Article 90(C) mandates that equipment be listed and labeled by a qualified testing laboratory such as UL, ETL, or CSA.

Working space in front of low-voltage equipment per NEC 110.26: 36 in for 0–150 V to ground, 42 in for 151–600 V, unless conditions require greater depth.

The NEC is adopted in California through Title 24, Part 3; local amendments may be stricter but not less safe than the state code.

Temporary power and extension cords must be protected by GFCI when used outdoors or in wet locations per California OSHA (Title 8, Section 2395).

A Class 2 circuit is limited to 100 VA and 30 V RMS; Class 3 is limited to 100 VA but may operate up to 150 V RMS.

Bonding jumpers around water meters and gas piping must be sized per NEC Table 250.102(C)(1) based on the largest ungrounded conductor.

NEC Article 725 governs Class 2 and Class 3 remote-control and signaling circuits; Class 2 cables include CL2P, CL2R, and CL2X.

NEC Article 800 governs communications circuits; CM, CMR, CMP, and CMX ratings correspond to general, riser, plenum, and limited-use applications.

Plenum-rated cable (CMP) must be used in air-handling spaces unless enclosed in conduit per NEC 300.22(C).

Cable support intervals: horizontal CAT cable every 4–5 ft, vertical cable every 3–5 ft, and within 12 in of boxes or enclosures.

Minimum bend radius for 4-pair UTP is four times the cable diameter during installation and one times the diameter after installation.

Fill capacity for a conduit is 40% for three or more cables and 53% for a single cable, per NEC Chapter 9, Table 1.

Separation between communications cable and Class 1 power conductors: at least 2 in for unshielded cable, unless a barrier is used per NEC 800.133.

Innerduct fill for fiber optic cable should not exceed 50% of the innerduct cross-sectional area to allow pulling without excess tension.

TIA-568 defines horizontal cable maximum length at 90 m (295 ft) plus 10 m (33 ft) of patch cords for a 100 m channel.

TIA-569 specifies pathway and space requirements, including minimum 1 in conduit for backbone and 2 in for horizontal riser sleeves.

TIA-606 labeling requires a unique identifier for each cable, termination point, and patch panel port; labels must be machine-printed.

TIA-570 covers residential cabling; a minimum of one outlet per room and two at the kitchen is a common design baseline.

Permanent link test limits exclude patch cords; channel test limits include them; both are defined in TIA-568.2-D.

Attenuation-to-crosstalk ratio (ACR) is calculated as insertion loss subtracted from near-end crosstalk (NEXT) in dB at each frequency.

Fiber optic loss budget = sum of connector losses (0.3–0.75 dB each), splice losses (0.1–0.3 dB each), and fiber attenuation (3.0 dB/km at 850 nm, 1.0 dB/km at 1310 nm).

NFPA 72 requires manual pull stations within 5 ft of each exit door and no more than 200 ft of travel distance on each floor.

Smoke detector spacing: 30 ft maximum between detectors on smooth ceilings; 15 ft from walls; 21 ft for 10 ft ceiling heights per NFPA 72 A.17.7.

Notification appliance circuits (NAC) must produce 15 dBA above ambient or 5 dBA above a maximum 105 dBA, whichever is greater, at 10 ft.

Class A circuits survive a single open; Class B circuits do not; both are defined in NFPA 72 Chapter 12.

California Title 19 requires smoke alarms in each sleeping room, outside each sleeping area, and on each story including basements.

Fire alarm control panels must be listed to UL 864 and installed per NFPA 72; monitoring must comply with UL 827.

Survivable fire alarm cable must be CI-rated and installed per NEC 760.176; riser cable must be FPLR, plenum FPLP, and general FPL.

Access control fail-safe locks unlock on power loss (used for egress); fail-secure locks remain locked on power loss (used for high-security).

Request-to-exit devices must release the door within 15 seconds per NFPA 101 and California Building Code Chapter 10.

CCTV camera resolution: 1080p is 1920×1080 pixels; 4K is 3840×2160; lens focal length determines field of view, not resolution.

PoE IEEE 802.3af supplies up to 15.4 W per port; 802.3at (PoE+) supplies up to 25.5 W; 802.3bt supplies up to 60 W or 100 W.

Balanced twisted-pair cable for access control readers uses Wiegand or OSDP; OSDP is the modern encrypted replacement for Wiegand.

Video storage calculation: GB per day = (bitrate in Mbps × 86,400) ÷ 8,000, then multiply by retention days and number of cameras.

Door position switches (DPS) are normally closed reed switches that open when the door is opened, signaling an alarm condition.

Speaker line loss: 25 V systems lose more power over distance than 70 V systems; use 70 V or 100 V for long runs.

Impedance matching: total speaker load in watts must not exceed amplifier rated wattage; 70.7 V constant-voltage systems use transformer taps.

HDMI 2.0 supports 18 Gbps and 4K at 60 Hz; HDMI 2.1 supports 48 Gbps and 8K at 60 Hz or 4K at 120 Hz.

RS-485 is a differential serial bus supporting up to 32 unit loads and 1,200 m (4,000 ft) at lower baud rates.

Balanced audio uses three conductors (hot, cold, ground) and rejects common-mode noise; unbalanced uses two conductors and is limited to short runs.

Control system relay outputs are typically dry contacts rated 1–2 A; inductive loads require suppression diodes or RC snubbers.

NEC 250.52 lists acceptable grounding electrodes; a ground rod must be at least 8 ft long and 5/8 in diameter, and must be bonded to the building grounding electrode system.

The grounding electrode conductor for a service is sized per NEC Table 250.66; for low-voltage systems, the equipment grounding conductor is sized per Table 250.122.

A single-point ground is required for communications systems to avoid ground loops; bond the telecommunications ground bar to the building ground with a minimum 6 AWG conductor.

Surge protective devices (SPD) are classified by location: Type 1 at service entrance, Type 2 at distribution panels, Type 3 at point of use.

SPD ratings include MCOV (maximum continuous operating voltage), clamping voltage, and surge current capacity in kA per mode.

Bonding of cable shields and conduits should occur at one end only to prevent circulating currents, unless a grounding kit is specified for both ends.

Category cable certification tests include wire map, length, insertion loss, NEXT, PS-NEXT, ACR, PS-ACR, return loss, and propagation delay.

Fiber optic testing uses an OLTS for loss and a OTDR for fault location; reference method per TIA-526-14 for multimode and TIA-526-7 for single-mode.

Continuity testing of fire alarm circuits must verify end-of-line resistor values and supervision per NFPA 72 Chapter 14.

As-built documentation must include cable schedules, panel schedules, test results, and device addresses; retain for the life of the system.

Troubleshooting open circuits: use a time-domain reflectometer (TDR) to locate the distance to the fault based on velocity of propagation.

Ground resistance testing uses the fall-of-potential method (three-point) or clamp-on meter; a reading of 25 ohms or less is the NEC target for a single rod.

California contractor licensing is governed by the Contractors State License Board (CSLB); low-voltage work typically requires a C-7 or C-10 license.

The California Building Standards Code (Title 24) includes Part 3 (Electrical), Part 4 (Mechanical), Part 5 (Plumbing), and Part 9 (Fire).

A permit is required for installation of low-voltage wiring in commercial buildings; residential low-voltage work may be exempt if under $500 and not part of a larger project.

California Labor Code Section 108 requires that only licensed contractors perform work; unlicensed contracting is a misdemeanor.

California Public Utilities Commission (CPUC) General Order 95 governs overhead line clearances; GO 128 governs underground construction.

The California Fire Code (Title 24, Part 9) adopts NFPA 1 and requires fire alarm permits from the local fire authority having jurisdiction (AHJ).

Workers' compensation insurance is required for all California contractors with employees; a $15,000 bond is required for a contractor license.