PE Controls

Question 1

Black conductor color generally indicates what?

Answer 1

Line, load, and control circuits at line voltage

Question 2

Red conductor color generally indicates what?

Answer 2

AC control circuits less than line voltage

Question 3

Blue conductor color generally indicates what?

Answer 3

DC control circuits

Question 4

Yellow conductor color generally indicates what?

Answer 4

Interlock control circuits powered from external power supply

Question 5

Green conductor color generally indicates what?

Answer 5

Equipment ground conductor where insulated or covered

Question 6

Red color pushbuttons generally indicate what?

Answer 6

Emergency stop, Stop, Off

Question 7

Yellow color pushbuttons generally indicate what?

Answer 7

Return, Emergency return, Intervention – suppress abnormal conditions

Question 8

Green color pushbuttons generally indicate what?

Answer 8

Start, On

Question 9

Per NFPA 79 (Industrial Machinery), power circuit conductors shall not be smaller than what size conductor?

Answer 9

14 AWG

Question 10

Per NFPA 79 (Industrial Machinery), lighting and control circuits on machine and in raceways conductors shall not be smaller than what size conductor?

Answer 10

16 AWG

Question 11

Per NFPA 79 (Industrial Machinery), control circuit conductors shall not be smaller than what size conductor?

Answer 11

18 AWG

Question 12

Per NFPA 79 (Industrial Machinery), electronic and control conductors in raceways conductors shall not be smaller than what size conductor?

Answer 12

24 AWG

Question 13

What industry standard covers proper grounding techniques for loading stations where static electricity hazards may occur?

Answer 13

NFPA 77

Question 14

What are the recognized means by which lightning induced voltage surges occur in mains or data/telecommunications cables?

Answer 14

Resistive coupling, inductive coupling, capacitive coupling

Question 15

What industry standard covers proper grounding techniques for lightning protection?

Answer 15

NFPA 78

Question 16

What industry standard covers wire sizing and color codes in industrial machinery?

Answer 16

NFPA 79

Question 17

What industry standard covers various environmental enclosure ratings?

Answer 17

NEMA 250

Question 18

A 480 volt three phase 50 HP motor draws 65 amps and is 600 feet away. What is the voltage drop, and what size wire should we use for a 5% voltage drop?

Answer 18

24volts drop maximum; 33,774cm (area circular mils; cm = ((sqrt(3) * L * I * k) / Vd); #4 AWG; k is specific resistance (k = ((R * cm) / 1000)

Question 19

What is the voltage drop for AWG 18 stranded wire 565 feet one way in coated cable? Wire carries 20 mA of dc current. Note: Coated (wires are jacketed); uncoated (wires are not jacketed).

Answer 19

191mV ((Vd = ((2*L) / 1000) * I * R)

Question 20

What is the DC voltage drop formula?

Answer 20

Vd = ((2 * L) / 1000) * I * R)

Question 21

What is the AC single phase voltage drop formula?

Answer 21

Vd = (((2 * L) / 1000) * I * Ze); (Ze with p.f. = 100 is equal to dc = R)

Question 22

What is the AC three phase voltage drop formula?

Answer 22

Vd = (((sqrt(3) * L) / 1000) * I * Ze); (Ze with p.f. = 100 is equal to dc = R); (Note: ((2 * L) / 1000) * I * Ze * Cos30) = (((2 * L) / 1000) * I * Ze * (sqrt(3) / 2)) = (((sqrt(3) * L) / 1000) * I * Ze)