North Carolina Low Voltage Practice flashcards
North Carolina Low Voltage Practice · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Class 2 circuit
- A power-limited circuit per NEC Article 725 that operates at 30 V or less and 100 VA or less, or as listed in Table 725.121, used for signaling and control.
- Plenum-rated cable
- Cable listed for installation in ducts, plenums, and air-handling spaces. Examples include CMP, CL2P, FPLP, and CATVP. It has low smoke and flame spread characteristics.
- Cable support interval
- Horizontal communications cable must be supported at intervals not exceeding 4.5 ft and within 12 in of boxes, per NEC Article 800 installation requirements.
- Abandoned cable rule
- NEC requires removal of accessible abandoned communications, Class 2/3, and optical fiber cables unless they are tagged for future use.
- Ohm's law
- The relationship E = I x R, where E is voltage in volts, I is current in amperes, and R is resistance in ohms. The basis for all circuit calculations.
- Power formula
- P = E x I, where P is power in watts, E is voltage, and I is current. Equivalent forms are P = I²R and P = E²/R.
- Voltage drop formula
- For single-phase circuits, VD = 2 x K x I x L / CM, where K is 12.9 for copper, L is length in feet, and CM is circular mils.
- Circular mils
- A unit of conductor area equal to the square of the diameter in mils (thousandths of an inch). 12 AWG copper has 6,530 circular mils.
- Article 725
- The NEC article covering Class 1, Class 2, and Class 3 remote-control, signaling, and power-limited circuits, including wiring methods and cable listings.
- Article 760
- The NEC article covering fire alarm systems, including non-power-limited (NPLFA) and power-limited (PLFA) fire alarm circuits and cable types FPL, FPLR, and FPLP.
- Article 800
- The NEC article covering communications circuits, including cable types CMP, CMR, CM, CMG, and CMX, and their permitted substitutions in buildings.
- Article 820
- The NEC article covering community antenna television and radio distribution systems, including coaxial cable types CATVP, CATVR, CATV, and CATVX.
- NC low voltage license
- A special restricted electrical license issued by the NC State Board of Examiners of Electrical Contractors, authorizing low voltage work up to 50 volts.
- Communications bonding conductor
- A conductor of at least 14 AWG copper, listed, and run as short and straight as practicable, bonding communications cable shields to the building grounding electrode system.
- Grounding electrode system
- The set of electrodes required by NEC 250.50, including metal water pipe, building frame, concrete-encased electrode, ground rod, and plate electrodes.
- Equipment grounding conductor
- A conductor sized per Table 250.122 that provides a low-impedance path from equipment enclosures back to the source, enabling overcurrent devices to clear faults.
- System bonding jumper
- The connection between the grounded conductor and the equipment grounding conductor at a separately derived system, installed at the source or first disconnecting means.
- Class A circuit
- A fire alarm signaling circuit that survives a single open or ground fault by providing a return path to the panel, maintaining operation of all devices.
- Class B circuit
- A fire alarm signaling circuit that does not survive an open; a break disables devices beyond the break, so it is used where reduced reliability is acceptable.
- Smoke detector spacing
- On a smooth ceiling, spot-type smoke detectors are spaced no more than 30 ft apart and within 15 ft of walls, and at least 3 ft from air diffusers.
- NAC voltage drop
- Notification appliance circuit calculation ensuring that the appliance at the end of the circuit receives at least its rated minimum operating voltage under alarm conditions.
- Fire alarm battery sizing
- Secondary supply must power the system for 24 hours of standby plus 5 minutes of alarm for commercial systems, or 24 hours plus 15 minutes for voice evacuation.
- TIA-568 channel length
- The maximum horizontal channel is 100 m, consisting of up to 90 m of permanent link plus 10 m of patch cords at the work area and cross-connect.
- Cat 6A cable
- Balanced twisted-pair cable rated to 500 MHz, supporting 10GBASE-T to 100 m. It typically requires larger conductors and more careful installation than Cat 6.
- OM3 fiber
- A laser-optimized 50/125 µm multimode fiber with 2000 MHz·km bandwidth at 850 nm, supporting 10GBASE-SR to about 300 m and 40GBASE-SR4 to 100 m.
- T568A versus T568B
- Two pinout standards for RJ-45 connectors that differ in the assignment of pairs 2 and 3 (green and orange). Either is acceptable if used consistently throughout a project.
- NC license classes
- Limited (up to 600 V), Intermediate (up to 600 V, unlimited), Unlimited (any voltage), and Special Restricted Low Voltage (up to 50 V) issued by the NC Board.
- Notice to Lien Agent
- A NC-required notice filed on projects over $30,000 by subcontractors and suppliers to preserve mechanics' lien rights on improved real property.
- Continuing education requirement
- NC electrical licensees must complete annual continuing education hours to renew their license; verify the current hour requirement with the NC State Board.
- Multimeter CAT rating
- A safety category rating for test instruments: CAT II for portable equipment, CAT III for distribution circuits, and CAT IV for service entrance measurements.
- Lockout/tagout
- A procedure requiring verification of de-energization, application of a lock and tag, and confirmation of zero energy before servicing equipment, per OSHA 1910.147.
- Ladder 4-to-1 rule
- For every 4 ft of working height, the ladder base is set 1 ft from the wall. Maintain three points of contact and do not stand on the top two rungs.