1 Box and Conduit Fill Calculations2 3 Volume required per conductor4 5 6 Conduit fill - Box sizing Table (a) : Number o...
Description
Box & conduit Fill Calculations
Box and Conduit Fill Calculations
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Volume required per conductor
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Conduit fill - Box sizing Table 314.16(a) : Number of conductors in box 600v, nominal or less
CONDUCTORS: 1.
Conductors originating outside box, terminating in box count as 1 conductor
2.
Conductors originating outside box, spliced in box counts as 1 conductor
3.
A conductor entering a box, spliced to a conductor leaving box counts as 2 conductors
4.
Conductors passing through box without splices or terminations count as 1 conductor
5.
A conductor of which no part leaves the box shall not be counted Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Conduit fill - Box sizing
2005 NEC Change
Looped conductors now count as 2 conductors
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
EQUIPMENT GROUNDING CONDUCTOR:
1.
One, two or more bare, insulated or covered system grounding conductors all count the same size, count as 1 conductor
2.
One, two or more bare, insulated or covered system grounding conductors of various sizes, count as one conductor based upon largest equipment grounding conductor
3.
A separate ‘ISOLATED’ equipment grounding conductor counts as 1 conductor in addition to system grounding conductor. Count as size of ‘ISOLATED’ grounding conductor or largest if various sizes.
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
CLAMPS: 1. Clamps installed inside box by factory count as 1 conductor 2. Clamps installed in box in the field count as 1 conductor (Conductor size based on largest conductor in box)
SUPPORT FITTINGS: 1. Fixture studs count as 1 conductor 2. Fixture hickeys count as 1 conductor (Conductor size based on largest conductor in box)
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
DEVICE(S) IN BOX: 1.
Yoke or strap with switch, counts as 2 conductors
2.
Yoke or strap with duplex receptacle counts as 2 conductors
3.
Yoke or strap with triplex receptacle counts as 2 conductors
4.
Yoke or strap with switch & light on same yoke or strap counts as 2 conductors
5.
Yoke with any combination of three devices on same yoke or strap counts as 2 conductors
(Conductor size based on LARGEST conductor connected to device or equipment)
2 - #8 @3.00 Cu Fix Stud @3.00 Cu in 4 - #12 @2.25 Cu in Total
= = = =
6 Cu in 3 Cu in 9 Cu in 18 Cu in
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations #8 AWG #14 Bare EGC #12 AWG
#18 AWG fixture wire #10 AWG #18 = 1.5 cu in x 2 #14 = 2.0 cu in x 1 #12 = 2.25 cu in x 4 #10 = 2.50 cu in x 2 #8 = 3.00 cu in x 2 Fix Stud = #8 = 3.00 cu in
= = = = = =
3.00 cu in 2.00 cu in 9.00 cu in 5.00 cu in 6.00 cu in 3.00 cu in
Total Box volume required = 28,00 cu in Copyright 1999-2007 Dan Dudley
Dome Canopy Terminations in Canopy Cover To Fixture To Fan
Do not count for Box Fill Calculations Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Counting with a device 2 - #8 AWG
2 - #12 AWG Largest conductor allowed = #10 NEC 110.14(A) 2 - #12 AWG
2 - #8 @3.00 cu in = 6 cu in 4 - #12 @2.25 cu in = 9 cu in Yoke @2.25 cu in = 4.5 cu in Total Volume Required = 19.5 cu in Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Conduit Fill Calculations
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Major Fraction Change
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
What size EMT is needed for 3 - 2/0 AWG THW Cu conductors and 4 - 4/0 AWG THHN Cu conductors ?
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
What size EMT is needed for 3 - 2/0 AWG THW Cu conductors and 4 - 4/0 AWG THHN Cu conductors ? Table 5 – Cross-Sectional Area of Individual Conductors 2/0 AWG THW Cu
=
.2624 X 3
4/0 AWG THHN Cu
=
.3237 X 4 =
1.2984
=
2.0820
Total Square Inches for Conductors
=
.7872
Table 4 – 40% fill column for “Over 2 wires”. 2.0820 Sq.In.
Requires a 2 ½ inch EMT Conduit
40% fill for 2 ½ inch EMT =
2.343 Sq. In.
Answer = 2 ½ Inch EMT Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
What size IMC is required for 6 - 12 AWG RHH Cu conductors without outer covering and 4 -14 AWG RHH Cu Conductors with outer covering ?
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
What size IMC is required for 6 - 12 AWG RHH Cu conductors without outer covering and 4 -14 AWG RHH Cu Conductors with outer covering ? Table 5 – Cross-Sectional Area of Individual Conductors 14 AWG RHH Cu With Outer Covering
=
.0293 X 4
=
.1172
12 AWG RHH Cu Without Outer Covering
=
.0260 X 6 =
.1560
=
.2732
Total Square Inches for Conductors Table 4 – 40% fill column for “Over 2 wires”. .2732 Sq.In.
Requires a 1 inch IMC Conduit
40% fill for 1 inch IMC
=
.384 Sq. In.
Answer = 1 Inch IMC Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Box & Conduit Fill Exam 10 Questions 30 Minutes
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Box fill Answers 1. (b) 10.75 cu in
314.16(b) 3 - #12’s @ 2.25 cu in = 6.75 cu in 2 - #14’s @ 2.00 cu in = 4.00 cu in 10.75 cu in
2. (b) 2 conductors
314.16 (b)
3. (b) 4
Table 314.16(a)
4. (d) 17.5 cu in
Table 314.16(b) #10 = 2.5 cu in 7 - #10’s x 2.5 cu in = 17.5 cu in
5. (a) 0.0181 in2
Table 5 (note * notations by insulations) * ONLY APPLIES TO RHH,RHW,RHW-2
Copyright 1999-2007 Dan Dudley
Box & conduit Fill Calculations
Box fill Answers 6. (d)
39.75 cu in
Table 314.16(b) #8 = 3.00 cu in #12 = 2.25 cu in Clamps -
#8 = 3.00 cu in
7 - #8 @ 3.00 cu in = 21.00 cu in 1 - #8 @ 3.00 cu in = 3.00 cu in 7 - #12 @ 2.25 cu in = 15.75 cu in 39.75 cu in
