Raceway and Box Calculations

Question 1

Primary references in the NEC for determining raceway size and conduit fill

Answer 1

Chapter 9 and Annex C

Question 2

Reference for when multiple conductors of the same size will be installed in a raceway

Answer 2

Annex C

Question 3

Reference for calculating raceway size based on different wires

Answer 3

Chapter 9

Question 4

Fill percentage of a raceway when one conductor is installed

Answer 4

53%

Question 5

Fill percentage of a raceway when two conductors are installed

Answer 5

31%

Question 6

Fill percentage of a raceway when three or more conductors are installed

Answer 6

40%

Question 7

Fill percentage of a nipple (>24”) long when conductors are installed

Answer 7

60%

Question 8

Wire jamming can occur when the ration of wire size to open space in a raceway is

Answer 8

2.80 and 3.20

Question 9

The maximum number of wires allowed into a metal wireway is limited to ____ % of the _____

Answer 9

20% of the cross sectional area

Question 10

Table for sizing boxes with wire sizes 6awg - 18awg

Answer 10

314.16(A)

Question 11

Table for determing volume required for wire sizes 6awg - 18awg

Answer 11

314.16(B)

Question 12

For box fill calculations, each conductor that is spliced is counted as

Answer 12

One

Question 13

For box fill calculations, each conductor that terminates is counted as

Answer 13

One

Question 14

For box fill calculations, each conductor that passes through the box without a 12” loop is counted as

Answer 14

One

Question 15

For box fill calculations, each conductor that passes through the box with a 12” loop is counted as

Answer 15

Two

Question 16

For box fill calculations, each conductor that originates in the box, and terminates in the box is counted as

Answer 16

Zero

Question 17

For box fill calculations, one or more clamps counts as ____ and is sized based on the ____

Answer 17

One

Largest conductor entering the box

Question 18

For box fill calculations, each luminaire hickey counts as ____ and is sized based on the ____

Answer 18

One

Largest conductor entering the box

Question 19

For box fill calculations, each yoke in the boxx counts as ___ and is based on the ___

Answer 19

Two

Largest conductor terminating on the device

Question 20

For box fill calculations, each multigang yoke count as ___ per gang, and is based on the ___

Answer 20

Two

Largest conductor terminating on the device

Question 21

For box fill calculations, all EGC’s entering a box count as ___ and is based on the ___

Answer 21

One

Largest EGC entering the box

Question 22

For box fill calculations, and isolated EGC counts as ___

Answer 22

One additional

Question 23

For box fill calculations involving wire sizes 4awg and larger, Table ____ must be used

Answer 23

314.28

Question 24

For straight pulls through a junction box, the size of the junction box must not be less than ___ times the size of the largest raceway entering the box

Answer 24

8

Question 25

For angle pulls through a junction box, the size of the junction box must not be less than ___ times the size of the largest raceway plus the sum of the trade sizes of the raceway(s) on the ___

Answer 25

6 Same row/side

Question 26

For U pulls through a junction box, the size of the junction box must not be less than ___ times the size of the largest raceway plus the sum of the trade sizes of the raceway(s) on the ___

Answer 26

6 Same row/side

Question 27

For splices pulls in a junction box, the size of the junction box must not be less than ___ times the size of the largest raceway plus the sum of the trade sizes of the raceway(s) on the ___

Answer 27

6 Same row/side