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PEC: special occupancies and equipment: board exam questions with solutions

On the RME exam under Philippine Electrical Code, Parts 1 and 2. Try each question before you open its solution.

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RCD protection: someone touches a live wire · Wiring, fuses and breakers for an array: the 1.25 and 1.56 rules: the same circuits on a live bench, with meters you can move.

Questions

1. In a dwelling unit, which of the following receptacle locations requires ground-fault circuit-interrupter protection for personnel?

  1. Bathrooms
  2. Bedrooms
  3. Living rooms
  4. Hallways
Show the answer and solution

Answer: A. Bathrooms

GFCI protection is required for receptacles in dwelling-unit bathrooms, along with other wet or grounded locations such as outdoors, garages and kitchen countertops.

Reference: PEC 2017 Part 1, 2.10.1.8 (GFCI protection for personnel)

2. A Class A ground-fault circuit interrupter trips when the current to ground reaches approximately what range?

  1. 30 mA to 50 mA
  2. 4 mA to 6 mA
  3. 100 mA to 300 mA
  4. 0.5 A to 1 A
Show the answer and solution

Answer: B. 4 mA to 6 mA

The fine print note to the GFCI definition states that Class A GFCIs trip when the current to ground is 4 mA to 6 mA.

Reference: PEC 2017 Part 1, Art. 1.1 (Definitions: Ground-Fault Circuit Interrupter, FPN)

3. What is the main purpose of equipotential bonding of the metal parts, reinforcing steel and pool water around a swimming pool?

  1. To provide the grounding electrode for the building service
  2. To carry the normal current of the pool pump
  3. To reduce voltage gradients in the pool area so swimmers are not exposed to shock from potential differences
  4. To permit the omission of GFCI protection
Show the answer and solution

Answer: C. To reduce voltage gradients in the pool area so swimmers are not exposed to shock from potential differences

The equipotential bonding grid ties all conductive parts in and around the pool to the same potential, so no dangerous voltage differences exist between surfaces a wet person can touch.

Reference: PEC 2017 Part 1, Art. 6.80 (Swimming Pools, Fountains, and Similar Installations)

4. After failure of the normal supply, within what maximum time must power be available to an emergency system?

  1. 60 seconds
  2. 30 seconds
  3. 2 minutes
  4. 10 seconds
Show the answer and solution

Answer: D. 10 seconds

Emergency systems must have power available within the time required for the application but not more than 10 seconds.

Reference: PEC 2017 Part 1, Art. 7.0 (Emergency Systems)

5. How must the wiring of an emergency system generally be installed relative to other building wiring?

  1. Kept entirely independent, not sharing raceways, boxes or cabinets with other wiring except where specifically permitted
  2. Run in the same raceways as normal lighting circuits to save cost
  3. Installed only as exposed flexible cord
  4. Shared with optional standby circuits in the same raceways
Show the answer and solution

Answer: A. Kept entirely independent, not sharing raceways, boxes or cabinets with other wiring except where specifically permitted

Emergency circuit wiring must be kept independent of all other wiring and equipment, apart from specific permitted locations such as transfer equipment.

Reference: PEC 2017 Part 1, Art. 7.0 (Emergency Systems)

6. A PV source circuit consists of one string of modules with a rated short-circuit current of 9.0 A. Applying the PV code rule for maximum circuit current and then the continuous-current rule for conductor sizing, what minimum conductor ampacity is required (before temperature and fill adjustments)?

  1. 9.00 A
  2. 14.06 A
  3. 11.25 A
  4. 18.00 A
Show the answer and solution

Answer: B. 14.06 A

Maximum circuit current = 125% × Isc = 1.25 × 9.0 = 11.25 A. Conductors must carry 125% of that: 1.25 × 11.25 = 14.06 A (156% of Isc).

Reference: PEC 2017 Part 1, Art. 6.90 (Solar Photovoltaic Systems: circuit sizing and current)

7. In hazardous (classified) locations, a Class I location is one where the hazard comes from:

  1. Combustible dust
  2. Ignitible fibers or flyings
  3. Flammable gases, flammable liquid-produced vapors or combustible liquid-produced vapors
  4. Corrosive chemicals
Show the answer and solution

Answer: C. Flammable gases, flammable liquid-produced vapors or combustible liquid-produced vapors

Class I covers flammable gases or vapors, Class II combustible dust, and Class III ignitible fibers or flyings.

Reference: PEC 2017 Part 1, Art. 5.0 (Hazardous (Classified) Locations)

8. The maximum DC voltage of a PV source circuit is determined using the module open-circuit voltage corrected to which condition?

  1. The highest expected ambient temperature
  2. Standard test conditions only (25 °C)
  3. The module's maximum-power-point voltage at noon
  4. The lowest expected ambient temperature
Show the answer and solution

Answer: D. The lowest expected ambient temperature

Module open-circuit voltage rises as temperature falls, so the maximum system voltage is calculated at the lowest expected ambient temperature.

Reference: PEC 2017 Part 1, Art. 6.90 (Solar Photovoltaic Systems: maximum voltage)

Other topics in the same subjects

PEC Part 1: general requirements · PEC: wiring methods and materials · PEC: branch circuits, ampacity and protection · PEC: grounding and bonding

An independent, free reviewer: not affiliated with the PRC or the Boards. Subject weights and passing rules are from the PRC examination programs and the laws (RA 9292, RA 7920); check the current PRC program before you file. Code questions follow the Philippine Electrical Code 2017 Part 1; check them against your own copy of the Code.