Written test: 2013 WV SkillsUSA Industrial Motor Controls contest

[fmtjfw]

10 points per correct answer. 2 points for each correct NEC reference.

Correction 70-836 last col.
for ?Dimensions of Chap 9. Table 4?
read ?Dimensions of Chap 9. Table 5?

CB circuit breaker
CCC Current Carrying Conductor
CU Copper
FLA Full-load amperage
OCPD Overcurrent Protective Device

All wire THWN-2 insulation

(1) What size EMT conduit is required for 6 #8 and 10 #14 wires?
A ?
B ?
C 1
D 1-?
E 1-?
Code Ref [2]

(2) What is the maximum ampacity for a #8 copper hot wire in a conduit with a total of 6 #8 CCC and 10 #14 motor control wires with ? amp loads?
A 15
B 27.5
C 44
D 55
E 75
Code Ref [3] 725.51(B)(2)

(3) What is the smallest box that can be used as a pull box (with no splices or terminations) for 3 #8 and 5 #14 conductors?
A 4x4x1-?
B 4x4x1-?
C 4x4x2-1/8
D 3x3x3
E 6x6x6
Code Ref [3]

(4) What size CU bonding conductor(s) is required for a PVC conduit containing two 3-wire 60-amp
Circuits and five 2-wire 15-amp circuits?
A #14
B #12
C #10
D 2 #10 & 5 #14
E #6
Code Ref [4]

(5) How many CCC are in a conduit containing a grounding wire and two 4-wire 3-phase Y circuits feeding incandescent lights?
A 4
B 5
C 6
D 7
E 8
Code Ref [2]

(6) How many CCC are in a conduit containing a grounding wire and two 4-wire 3-phase Y circuits feeding computers?
A 4
B 5
C 6
D 7
E 8
Code Ref [2]

(7) What is the maximum simultaneous CCC in a conduit containing a grounding wire, three sets of 3-way travelers and a neutral all fed from a single-pole CB?
A 3
B 4
C 5
D 6
E 7
Code Ref [2]

(8) For purposes of calculations what is the FLA For a 3-phase 7-? HP 460 V motor?
A 40
B 20
C 19
D 11
E 9
Code Ref [1]

(9) What wire size is required for conductors feeding a motor with a full-load amperage of 15?
A #18
B #16
C #14
D #12
E #10
Code Ref [1]

(10) What overload relay trip setting is used for a motor with FLA of 15, service factor 1.0, & 60?C rise?
A 15 10
B 16.5
C 17.25
D 18.75
E 20
Code Ref [1]

(11) How many overloads are needed for a 3-phase motor fed from a corner-grounded Delta?
A 1
B 2
C 3
D 4
E 5
Code Ref [1]

12) What is the maximum instantaneous breaker ampacity for a FLA of 15 Amps (ignoring exceptions)?
A 15
B 40
C 80
D 120
E 125
Code Ref [2]

(13) What is the maximum Time-delay fuse ampacity for a FLA of 15 Amps (ignoring exceptions)?
A 15
B 20
C 25
D 26.25
E 30
Code Ref [4]

(14) What is the maximum OCPD size for protecting #14 CU motor control conductors in a conduit?
A 20
B 30
C 45
D 100
E 120
Code Ref [1]

(15) What enclosure type is rated for temporary Submersion?
A 3 10
B 3R
C 4X
D 6
E 12K
Code Ref [1]

 

[augie47]

Check This:
(1) C, (2) C, (3) B, (4) C {Bonding? }, (5) C, (6) E, (7) B, (8) D, (9) C, (10) C, (11) C, (12) B, (13) E,
(14) A, (15) D

Woud I pass ?

 

[fmtjfw]

Check This:
(1) C, (2) C, (3) B, (4) C {Bonding? }, (5) C, (6) E, (7) B, (8) D, (9) C, (10) C, (11) C, (12) B, (13) E,
(14) A, (15) D

Woud I pass ?

You would have gotten the best post-secondary score (non-traditional student) the highest we got was 89. You could have done better by filling in code references.

110 points for answers out of 150. 0 out of 60 for code references total possible points 210

Below is how we figured the answers for the questions you missed. You are welcome to point out any errors we made.

(3) To calculate the box size you need to calculate the allowance for each of the wires:
Wire Quantity Area Value
#8 6 3.00 18.00
#14 5 2.00 10.00
Total 28.00
This is from ?Table 314.16(A)?. Note that all conductors pass through the box without termination or
splicing so they are counted only once under ?310.16(B)(1)?. Now that we have the total allowance, the
next step is to find the smallest box that has a volume of 28 in.? and is in the list of possible answers.
We use ?Table 314.16(A)? for this.
Index entry; Boxes ? Fill calculations
Code Ref: 314.16(B)(1), Table 314.16(A), Table 314.16(B)

(9) ?430.22? states that the conductors have an ampacity of not less than 125% of FLA. FLA is 15 so
15*125% is 18.75.
Index entry: Motors ? Branch Circuits
Code Ref: 430.22

(12) ?430.52(C)(1)? and ?(3)? refer to ?Table 430.52? and instantaneous circuit breakers. Normal 3-
phase motors have a percentage factor of 800%. So 15*800% is 120. Note from ?430.52(C)(3)? these
breakers must be adjustable, so the standard circuit breaker sizes do not apply. [? credit for 125]
Index entry: Motors ? Branch Circuits ? Short-circuit & ground-fault protection
Code Ref: 430.52, Table 430.52

(14) ?Table 430.27(B)? ?Column C? applies to conductors extended beyond the enclosure. The
Ampacity for ?#14 CU? conductors is 45.
Index entry: Motors ? Control circuits
Code Ref: Table 430.27(B)

 

[augie47]

You would have gotten the best post-secondary score (non-traditional student) the highest we got was 89. You could have done better by filling in code references.

110 points for answers out of 150. 0 out of 60 for code references total possible points 210

Below is how we figured the answers for the questions you missed. You are welcome to point out any errors we made.

(3) To calculate the box size you need to calculate the allowance for each of the wires:
Wire Quantity Area Value
#8 6 3.00 18.00 I believe the question referenced (3) #8s passing thru (3) X 3=9 + 10 = 19
#14 5 2.00 10.00
Total 28.00
This is from “Table 314.16(A)”. Note that all conductors pass through the box without termination or
splicing so they are counted only once under “310.16(B)(1)”. Now that we have the total allowance, the
next step is to find the smallest box that has a volume of 28 in.? and is in the list of possible answers.
We use “Table 314.16(A)” for this.
Index entry; Boxes – Fill calculations
Code Ref: 314.16(B)(1), Table 314.16(A), Table 314.16(B)

(9) “430.22” states that the conductors have an ampacity of not less than 125% of FLA. FLA is 15 so
15*125% is 18.75. Ignoring termination rules #14 TGWN-2 has an ampacity of 25, 20 at 75 deg.
Index entry: Motors – Branch Circuits
Code Ref: 430.22

(12) “430.52(C)(1)” and “(3)” refer to “Table 430.52” and instantaneous circuit breakers. Normal 3-
phase motors have a percentage factor of 800%. So 15*800% is 120. Note from “430.52(C)(3)” these
breakers must be adjustable, so the standard circuit breaker sizes do not apply. [? credit for 125]
Index entry: Motors – Branch Circuits – Short-circuit & ground-fault protection Agree opps
Code Ref: 430.52, Table 430.52

(14) “Table 430.27(B)” “Column C” applies to conductors extended beyond the enclosure. The
Ampacity for “#14 CU” conductors is 45.
Index entry: Motors – Control circuits This one might be debatable. The question does not indicate if the conductors are protected by separate protection or the motor branch circuit protective device.
45 would be correct IF it's the motor protective device. If not, 310.15 is applicable.
240.4(G) overrules 240.4(D)(3) so #14 would have an allowable ampacity of 20 amps.
Code Ref: Table 430.27(B)

Not being obstinent, just showing a different view of the questions

 

[fmtjfw]

(9) ?430.22? states that the conductors have an ampacity of not less than 125% of FLA. FLA is 15 so
15*125% is 18.75. Ignoring termination rules #14 TGWN-2 has an ampacity of 25, 20 at 75 deg.
Index entry: Motors ? Branch Circuits
Code Ref: 430.22

(14) ?Table 430.27(B)? ?Column C? applies to conductors extended beyond the enclosure. The
Ampacity for ?#14 CU? conductors is 45.
Index entry: Motors ? Control circuits This one might be debatable. The question does not indicate if the conductors are protected by separate protection or the motor branch circuit protective device.
45 would be correct IF it's the motor protective device. If not, 310.15 is applicable.
240.4(G) overrules 240.4(D)(3) so #14 would have an allowable ampacity of 20 amps.
Code Ref: Table 430.27(B)

I've added motor branch to question 14 to remove that ambiguity.

I looked through 430 and was unable to find anything referenced by 240.4(G) that allowed increased ampacity over 240.4(D)(3) for #14. I found lots about increased OCPD values. I really want to know if I missed it in 430.

Thanks