Questions and Answers
Multiple Class 2 or Class 3 power supplies can be wired in parallel with each other.
False
Coaxial cable connecting a video camera to a monitor is an example of integral wiring.
False
Class 1 circuits typically operate from greater voltage and current levels than those of Class 2 or 3 Circuits.
True
Class 1 circuits that are not functionally associated must be separated from power conductors by a solid and firmly fixed barrier.
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Insulation requirements for Class 1 conductors 18 and 16 AWG must be suitable for 600 V.
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Class 3 conductor may be smaller than 18 AWG.
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Class 3 power supplies may operate up to a maximum of 1000VA.
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Instrumentation tray cable can be used as a substitute for Class 3 wiring.
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If an equipment failure were to introduce a direct life or fire hazard, the circuit must be reclassified as Class 1.
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All Class 2 conductors may be strapped or attached to the exterior of a conduit.
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Class 2 circuits may be installed in the same enclosure or cable with conductors of Class circuits provided:
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Power sources for Class 2 or Class 3 circuits may be derived from:
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A power limited Class 1 circuit may operate at a maximum of:
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Pipe fill is required for which of the following circuits?
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The overcurrent protection device for Class 1 circuits may be rated to:
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Signaling circuits include:
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Class 2 circuit conductors shall be insulated to a maximum of:
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Class 2 or Class 3 conductors may be run in the same raceway with Class 1 circuits provided:
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Class 2 or Class 3 conductors may be installed within enclosures including electric light and power circuits provided:
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Exterior run Class 2 and Class 3 circuits must maintain a minimum separation of blank from Class 1 electric light and power circuits.
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In elevators, power limited circuits must be installed:
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Class AC power supplies between 30V through 150V may operate at a maximum of:
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Class 2 or Class 3 audio circuit conductors, in accordance with section 640.9 of the NEC, occupy the same cable or raceway with other Class 2 or Class 3 remote control or signaling circuits.
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A power limited Class 3 power supply must never exceed:
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The rating on power limited tray cable should be rated for blank V and not less than blank AWG.
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Study Notes
Class Circuits Overview
- Multiple Class 2 or Class 3 power supplies cannot be wired in parallel.
- Insufficient insulation is necessary for Class 3 conductors; they must not be smaller than 18 AWG.
- Class 1 circuits typically operate at higher voltage and current levels compared to Class 2 or 3.
Class Circuit Requirements
- Class 1 circuits need separation from power conductors via a solid and fixed barrier.
- Class 1 conductors of 18 and 16 AWG must be suitable for 600V insulation.
- If a circuit failure poses direct life or fire hazards, it must be reclassified as Class 1.
Installation Guidelines
- Class 2 circuits can only be installed with Class 1 circuits if they are functionally associated.
- Class 2 conductors can be strapped to conduits, but not all Class 2 conductors can.
- Class 2 or 3 conductors may run alongside Class 1 conductors with a minimum of 2-inch separation.
Circuit Specifications
- Class 2 circuit conductors should be insulated for a maximum of 150V.
- The overcurrent protection device for Class 1 circuits can be rated up to 167% of the power supply rating.
- Power limited Class 1 circuits can operate at 30V maximum with 1000VA.
Electrical Standards
- Power limited Class 3 supplies cannot exceed 300V and 100VA.
- Class AC power supplies between 30V and 150V are limited to a maximum of 5mA.
- Power limited tray cables must be rated for 300V and at least 22 AWG.
Special Conditions
- In elevators, power limited circuits should be installed inside rigid metal or nonmetallic conduits.
- Audio circuits require pipe fill across various setups, ensuring proper protections.
- Class 2 and 3 audio circuit conductors cannot occupy the same cable or raceway as other remote control or signaling circuits.
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Description
Explore the key differences and requirements for Class 1, Class 2, and Class 3 electrical circuits in this comprehensive quiz. Understand the specifications regarding insulation, conductor sizes, and installation guidelines essential for safe wiring practices. Test your knowledge of electrical circuit classifications today!
