Two Minute Drill Raceways and Boxes 2017 Ted

Two Minute Drill: Raceways and Boxes 2017 ©Ted “Smitty” Smith 2008, 2011, 2014, 2017

Instructions This speed drill is designed to help you practice calculations. The slides will transition in three and one half minutes instead of two minutes. Attempt to answer the questions and then when the slide show completes, Check your answer. When you reach the end of the drill all of the slides will be repeated without the timer so you will have time to check and verify your answers at that time. Click on the left mouse button to begin.

BOX FILL REMINDERS Junction Boxes with Conductors 6 AWG or Smaller • USE 314. 16(B) The steps to the calculation are laid out step by step in the NEC Use the volume allowances found in Table 314. 16(B) and apply them as required 1. Count all the conductors entering the box and any conductor passing through the box Any conductor that passes through the box and has a loop that is 12” is or greater has to be counted as two conductors because later on it could be cut to make two conductors 2. Does the box have any internal cable clamps If it does, count 1 volume allowance for each TYPE of internal cable clamp based on the largest conductor in the box 3. Does the box have any fixture studs or fixture hickeys If it does, count 1 volume allowance for each type in the box based on the largest conductor in the box 4. Does the box have any devices If it does, count 2 volume allowance for each yoke based on the largest conductor connected to the device. 5. Now count 1 volume allowance for the equipment grounds based on the largest equipment ground in the box. These conductors do not carry current so it doesn’t matter how many you have. You only count 1 volume allowance. Important Things to Remember • • • Any box that has a barrier installed for the purposes of separating systems or to meet code requirements. Each space separated by the barrier shall be calculated as if it was a separate box. – Also the barrier has to be taken into account as space used in both spaces on either side of it. If it is not marked with its volume allowance, it is calculated at ½” if metal and 1” if non-metallic. IF A BOX CONTAINS A CONDUCTOR WHICH IS 4 AWG OR LARGER. The box fill rules of 314. 16(B) do not apply. – These boxes must be calculated using the Pull Box rules in 314. 28 – Based on the raceways sizes entering the box – Straight Pulls • Must be at least 8 times the largest raceway entering the box – Angle or U Pull • Must be 6 times the largest conductor on one side then add the raceway sizes of all the other conduits on the same side. • Do this for any side that has raceways entering it. • Raceways have to be installed in rows. So it there is more than one row raceways entering a side, then you only account for the row which gives you the highest result Any time two conduits in a box encircle the same conductor, the two conduits must be at least 6 times the largest diameter of the raceways apart.

Examples for Pull Boxes and Junction Boxes Containing Conductors Sized 4 AWG or Larger

Raceway Calculations Table 4 • • Be sure to use the correct table for the type of raceway you are using Be sure to use the correct column – 60% if the raceway is a nipple (24” or shorter) – 40% if the raceway contains more than 2 conductors – 31% of the raceway contains only two conductors – 53% if the raceway contains only 1 conductor Table 5 • • Be sure to use the area of the conductor, not the diameter Be sure to use the correct insulation Only use Table 5 A if you are sizing for Compact Aluminum Conductors Notice the * at the end of the Table – Rubber insulated conductors can be ordered with a nylon outer covering to help them pull through raceways. – If the conductors you are using have the outer covering then use the values for RHH, RHW or RHW-2 that do not have an * – If they do not have an outer covering use the values with the *

Metric versus Imperial Don’t let this throw you off if the question is asked using Metric designators. The code book specifically tells us to not covert measurements. This is because the code book uses two different methods to do conversion depending on the application. SO……the code book gives us the conversions for us. Every measurement in the NEC is listed in both Metric (Standard) and Imperial ( What we Americans call Standard. ) • When doing the calculation simply use the values that are listed. – If the question is asking for the Trade Size then use the Imperial values on Table 5 and the Imperial Values on Table 4 – If the question is asking for the Metric Designator then use the Metric values on Table 5 and the Metric Values on Table 4

• Step 1: Determine the area used by the conductors. Wireways, Gutters, ETC Often times questions about wireway and gutter fill throw people off on the test. These calculations are actually fairly simple once you learn the process. The following articles use the formula to the right: Auxiliary Gutters 366. 22 20% Cellular Concrete Floor Raceways 372. 22 40% Cellular Metal Floor Raceways 374. 22 40% Metal Wireways 376. 22 20% Nonmetallic Wireways 378. 22 20% – Use the values in Table 5 for the size and insulation of the conductors. – Get the total of all the conductors • Step 2: Divide the total in step 1 by. 20 (20%) or. 40(40%) depending on the applicable Article to the right. • Step 3: The answer to two will be the minimum area gutter or wireway you will need. • Find the area of your box – Multiply the width by the length

A 3 ½” Round Pancake box which is ½” deep and has four NM knockouts and internal cable clamps may contain a maximum of ________ 12 AWG ungrounded and grounded conductors if the box will contain one equipment grounding conductor? The box is marked by the manufacturer with a volume allowance of 3. 8 cu inches. A. 0 B. 1 C. 2 D. 3 Question 1

Answer Question 1 Copyright 2005 Ted "Smitty" Smith A. 0 314. 16(A)

What is the maximum number of 12 AWG conductors which can be spliced in a 1 ¼” LR Condulet if the Condulet is marked with a volume allowance of 14. 6 Cubic Inches? A. 3 B. 4 C. 5 D. 6 Question 2

D. 9 Answer Question 2 314. 16(C) Copyright 2005 Ted "Smitty" Smith

Question 3 What is the minimum sized metal wireway which may be used if it is to contain (20) 500 k. CMIL Compressed aluminum THHN conductors and (1) 3/0 THHN copper conductor and (3) 2/0 Compressed Aluminum THHN conductors? A. 24” x 12” x 4 feet B. 8” x 10” x 2 feet C. 8” x 18 “ D. 10” x 36”

C. 8” x 10” x 2 feet 366. 22 80” Answer 3 20 x.

Determine the minimum cross sectional area required for a cellular metal floor raceway which will be used to house (36) 10 AWG THHN conductors and (19) 8 THHN AWG conductors and (5) 6 AWG THHN conductors? A. 8. 54 inches B. 17 inches C. 33 inches D. 28 cubic inches Question 4

A. 8. 54 inches Answer 4 374. 22 Total wire volume 1. 7085/. 20=8.

Question 5 What is the minimum cellular concrete floor raceway cross sectional area required if the following conductors are to be installed: (12) 500 k. CMIL RHH without outer covering (4) 250 k. CMIL RHH without outer covering (1) 1/0 RHH without outer covering A. 20” B. 18” C. 16” D. 14”

Answer 5 372. 22 A. 20” Copyright 2005 Ted "Smitty" Smith

What is the minimum metric designator HDPE conduit which can be used for a conduit which is 24 feet in length and will contain the following conductors: 16 (12) THHN 10 AWG 8 (4) THW 6 AWG 9 (1) THHN 12 AWG A. 1 ½” B. 2” C. 3” D. 4” Question 6

Answer 6 Tables 4 and 5 C. 3” Copyright 2005 Ted "Smitty" Smith

Question 7 A 1” EMT contains (6) 12 AWG THHN conductors, (4) 10 AWG THW conductors and (1) 12 AWG THWN conductor. How many 12 AWG THWN conductors may be added to the conduit? A. 4 B. 7 C. 8 D. 11

Answer 7 D. 11 Tables 4 and 5 Copyright 2005 Ted "Smitty" Smith

Question 8 A two gang device box will contain two single switches. A permanent device barrier will be installed between the switches because they are switching two different phases of 277 V lighting circuits. Each side of the barrier will contain a single pole switch and a 12/3 MC cable with ground. The barrier is nonmetallic and no volume allowance is marked on the barrier. What is the minimum volume required for each side of the barrier? A. 12. 87 B. 16. 2 C. 20 D. 22. 5

Answer 8 A. 12. 87 314. 16(B)(15) Copyright 2005 Ted "Smitty" Smith

Question 9 Conduits which enclose the same conductor and enter a pull box as an angle pull, shall be located so that not less than ________ distance is between the conduit entries. A. 4 times the largest conduit trade size B. 6 times the largest conduit trade size C. One half the largest conduit trade size D. One third the largest conduit trade size

Answer 9 B. 6 Times 314. 28 Copyright 2005 Ted "Smitty" Smith

Question 10 Non-combustible surfaces which are broken or incomplete around boxes employing a flush type cover or faceplate shall be repaired so there will be no gaps or open spaces greater than ________ inches at the edge of the box. A. 1/8 inch B. ¼ inch C. ½ inch D. ¾ inch

Answer 10 A. 1/8 inch 314. 21 Copyright 2005 Ted "Smitty" Smith

Question 11 Determine the MAXIMUM number of size 300 kcmil RHW copper conductors, without outer covering, permitted to be installed in an 18 inch long, trade size 4”, electrical metallic tubing. A. 14 B. 15 C. 16 D. 17

Answer 11 C. 16 Table 4 and Table 5 Copyright 2005 Ted "Smitty" Smith

Question 12 A junction box contains THHN conductors which are feeding 208 V three phase circuits, 120 V single phase circuits and 480 V three phase circuits. Is this an acceptable installation according the NEC? A. Yes B. No

Answer 12 Yes 300. 3(C)(1) Copyright 2005 Ted "Smitty" Smith

Question 13 A single gang FS box with single cover will have two ½” raceways entering the box from opposite sides. The box will contain four (4) THNN size 12 AWG conductors and three (3) THHN size 12 equipment grounding conductors and one duplex receptacle. Is this an acceptable installation according the NEC? A. Yes B. No

The total fill is 15. 75 and a FS single cover is only 13.

Question 14 How many 12/2 AWG with ground, nonmetallic sheathed cables, are permitted to be installed in a device box having a total volume of 18 cubic inches where a duplex receptacle outlet is in the box? A. 1 B. 2 C. 3 D. 4

Answer 14 B. 2 314. 16(B)(15) Copyright 2005 Ted "Smitty" Smith Table 314. 16(B)

Question 15 A metal wireway is to contain the following listed copper conductors: Eight (8) size 500 kcmil THWN Twenty four (24) size 2 AWG THWN Which one of the following listed wireways is the MINIMUM size to house the conductors? A. 10” x 10” B. 6” x 6” C. 8” x 8” D. 12” x 12”

C. 8” x 8” Answer 15 376. 22(A) Copyright 2005 Ted "Smitty" Smith

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