CODE HUNTER — Voltage, 2014 NEC

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1680

To play this game, you need a sharp eye, a quick mind and a 2014 National Electrical Code book. (Fill-in-the-blank questions are looking for the exact word(s) used in the NEC.)

1) “Equipment that controls dc voltage or dc current, or both, and that is used to charge a battery or other energy storage device” is the definition of a(n):

  1. A) Inverter
  2. B) Generator
  3. C) Transformer
  4. D) Charge controller

2) Low-voltage cables connecting to oil-filled units that are not completely sealed, such as transformers, condensers, oil coolers, and high-voltage switches, shall have insulation of the __________ type.

  1. A) Shielded
  2. B) Oil-resistant
  3. C) Wet location
  4. D) Thermoplastic

3) Throughout this Code, the voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the __________ voltage of a circuit to which it is connected.

  1. A) RMS
  2. B) Actual
  3. C) Nominal
  4. D) Measured

4) Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of __________ amperes at a supply voltage of 1000 volts or less.

  1. A) 800
  2. B) 1200
  3. C) 2000
  4. D) 4000

5) The voltage developed between the portable or mobile equipment frame and ground by the flow of maximum ground-fault current shall not exceed __________ volts.

  1. A) 5
  2. B) 30
  3. C) 60
  4. D) 100

6) Conductors having __________ insulation and operating at different voltage levels shall not occupy the same enclosure, cable, or raceway.

  1. A) Thermoset
  2. B) Nonshielded
  3. C) Silicone rubber
  4. D) Flame-retardant

7) In addition to the uses permitted elsewhere in 392.10, nonmetallic __________ shall be permitted in corrosive areas and in areas requiring voltage isolation.

  1. A) Cable
  2. B) Tubing
  3. C) Conduit
  4. D) Cable tray

8) Type MV cables are rated 2001 volts and higher, and are allowed to be used on power systems rated up to and including 65,000 volts, nominal.

  1. A) True
  2. B) False

9) A Low-Voltage Suspended Ceiling Power Distribution System is defined as: “A system that serves as a support for a finished ceiling surface and consists of a busbar and busbar support system to distribute power to utilization equipment supplied by a Class 2 power supply.”

  1. A) True
  2. B) False

10) As long as they are on the same premise, receptacles connected to circuits that have different voltages, frequencies, or types of current (ac or dc) may be designed to accept interchangeable attachment plugs.

  1. A) True
  2. B) False

Bonus Question

[WpProQuiz 6]

Answers

1) D, Charge controller. This new and improved definition moved from Article 690 to Article 100 in the 2014 NEC. The language stayed the same with the exception of the addition of the phrase “or other energy storage device” at the end of the definition.

2). B, Oil-resistant. This requirement is found in 517.78(B), which applies to X-ray equipment guarding and grounding in health care facilities. According to the UL Wire and Cable Marking Guide, oil-resistant type cables are marked as follows:  A product evaluated for 60°C oil resistance is marked ”OIL RESISTANT I”, ”OIL RES I”, ”OIL RESISTANT” or “PRI.” A product evaluated for 75°C oil resistance is marked ”OIL RESISTANT II”, ”OIL RES II”, or “PRII.”

3) C, Nominal. This language is found in 110.4, and the definition of nominal voltage is: Voltage, Nominal. A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). There were numerous public inputs for the 2017 NEC requesting changes to the use of “nominal” and “actual” voltage. The code-making panel decisions can be read by going to nfpa.org/70 and downloading the “Public Inputs with Responses” file, found under the “Next Edition” tab in the middle of the page.

4) C, 2000. This allowance for buildings or structures supplied by a feeder(s) or branch circuit(s) is found in 225.30(C). Typically, a building or structure is allowed to be fed by only one circuit, but there are numerous exceptions for special conditions, special occupancies, capacity requirements, different characteristics of supply, and documented switching procedures.

5) D, 100. This requirement is found in 250.188(C). The voltage threshold for systems supplying portable or mobile equipment was changed from 600 volts to 1000 volts in the 2014 NEC, but the 100-volt limitation on the maximum ground-fault current remained unchanged.

6) B, Nonshielded. This language is found in 300.3(C)(2) and applies to conductors used in systems operating at over 1000 volts. This voltage threshold was also changed from 600 volts in the 2011 NEC to 1000 volts in the 2014 NEC.

7) D, Cable tray. In 392.10(D), nonmetallic cable tray is specifically allowed for use in corrosive areas and those areas requiring voltage isolation. Nonmetallic cable trays are often used in harsh environments like offshore oil and gas applications.

8) B, False. While there are cables manufactured for use in higher voltage systems, 328.10 states that Type MV cable is permitted on power systems rated up to and including 35,000 volts. Type MV cables are listed to UL 1072, and may be single- or multi-conductor, with aluminum or copper conductors.

9) A, True. Article 393 for Low-Voltage Suspended Ceiling Power Distribution Systems is a new article added in the 2014 NEC. The definition is found in 393.2, and the systems are intended for use in indoor dry locations at a maximum voltage of 30 volts ac or 60 volts dc.

10) B, False. 406.4(F) Noninterchangeable Types requires that receptacles used on circuits with differing characteristics must be designed to accept only a specific type of attachment plug intended for the voltage, frequency and type of current (ac or dc) on that circuit. This prevents equipment evaluated for a specific type of supply from being used on a system not intended for that equipment. An example would be using a 120 volt appliance on a 240 volt system, which could create a hazard. Standard receptacle configuration tables are available at NEMA.org.