Grounding Exam (12/20/99)
 

Title _________________________________         Years in the Industry: ________

Current Flow

1.     Electrons leaving a power supply are trying to get to “Ground” (the earth).

(a)   True                        (b) False

Electrons Take the Least Resistive Path

2.     Electrons take the path of least resistive. Example: A person (resistance of 1000 ohms) in contact with an energized metal object will be somewhat protected, if the energized meal object is grounded to the earth having a resistance of 20 – 25 ohms.

(a) True                        (b) False        

Equipotential Plane Reduces Touch Potential

3.     An existing metal light pole is supplied with 2-wire UF cable without an equipment grounding conductor (safety ground). This installation can be made safer by reducing the touch potential by establishes an equalized potential at the base of the pole by bonding the metal pole to the earth with a ground rod having a resistance not over 25 ohms.

(a)   True                        (b) False        

 

Earth Grounding Reduces Touch Potential

4.     An existing 2-wire ungrounded-type receptacle in an outlet box that has no equipment ground and it is replaced with a 3-wire grounding-type receptacle. Since there is no ground in the outlet box, the grounding terminal of the receptacle was bonded to a ground rod with a resistance of 25 ohms. Even though the installation does not meet all of the NEC requirements, the installation is still safe.

(a)   True                        (b) False

Earth Grounding Reduces Touch Potential

5.     The grounding electrode on the secondary of a low voltage (under 600 volts) transformer is intended to help remove (open protection device) dangerous voltage imposed on the metal parts of the electrical system from a secondary line-to-ground fault.

(a) True                        (b) False

Earth Ground (Ground Rod) Protects Outdoor Lighting Fixtures

6.     Ground rods installed at light poles in parking lots are intended to protect the lighting fixture (lamps/ballast) from lightning damage.

(a)   True                        (b) False        

Isolated Ground Reduces Noise

7.     To improve the performance of sensitive electronic equipment, an isolated grounding conductor from the electronic equipment can be connected to an electrically isolated electrode. Note: There is no electrical connection between the isolated electrode for the electronic equipment and building’s electrical system.

(a) True                        (b) False

Isolated Ground Reduces Noise

8.     An isolated ground receptacle more effective in reducing electrical noise if the receptacle’s grounding contacts terminate at the panelboard instead of the metal outlet for the receptacle.

(a)   True                        (b) False

 

Neutral-to-Ground Voltage

9.     The voltage between the neutral and ground at a receptacle is 5 volts when a 12 ampere load is on, and the voltage is only 2 volts when the load is not on. Steps should be taken to reduce this difference of potential.

(a) True                        (b) False        

Neutral Current Shock

10.  The electric shock for a person in series with a neutral is more severe then the shock from a hot wire. Another way of saying this is, “the shock from a neutral is worst than the shock from the hot wires.”

(a) True                        (b) False

Neutral Current Shock

11.  A person in series with a neutral conductor (carrying 1 ampere) will not receive an electric shock as serious as the shock from a circuit where the neutral conductor is carrying 16 amperes. Also, if the load on the neutral is electric discharge (fluorescent lighting) the shock will be more sever then if the load were resistive (incandescent).

(a)   True                        (b) False

Neutral Used For Grounding

12.  An existing 2-wire receptacle in an outlet box that has no equipment ground is replaced with a 3-wire receptacle and the grounding terminal of the new receptacle is jumped to the neutral terminal. This installation does not meet the NEC, but it’s safer than not grounding the receptacle.

(a) True                        (b) False

Equipment Ground for GFCI Device

13.  An equipment grounding conductor (safety ground) provides the low impedance path necessary for the proper operation of a GFCI protection device.

(a)   True                        (b) False

 

Equipment Ground for GFCI Device

14.  The test/reset button of GFCI receptacle will not always operate properly if the GFCI receptacle has no equipment ground.

(a)   True                        (b) False

GFCI Protection from Line-to-Neutral Fault

15.  Sever electric shock or death cannot occur if a person touches a hot and neutral wire at the same time of a GFCI protected circuit.

(a)   True                        (b) False

Grounding Separately Derived System – Section 250-20(d) and 240-30

16.  A permanently installed generator supplies a transfer switch, which “does not open the neutral”. The generator is considered a separately derived system and it must have a neutral-to-ground bond and it must be grounded to the nearest available grounding electrode.

(a) True                      (b) False        

Grounding Separately Building – Section 250-32

17.  A grounding electrode is not required at the remote building or structure if the feeder to that building contains a properly sized equipment grounding conductor (safety ground).

(a) True                        (b) False        

  Go to top of page
Newsletter Registration   |   Stay Connected:
 

888.NEC.CODE (632.2633) 3604 PARKWAY BLVD, STE 3, LEESBURG FL 34748  

Tell a Friend About This Site

  NEC® and National Electrical Code® are registered trade marks
of the National Fire Protection Association (NFPA).
  ©Copyright 2011 Mike Holt Enterprises, Inc.