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370-16. Number of Conductors In Outlet, Device, and Junction Boxes, and Conduit Bodies. Boxes and conduit bodics shall be of sulficient size to provide fi'ee space Ibr all enclosed conductors. In no case shall the volwne ofUle box, as calculatcd in (a) below, be less than the fill calculation as calculated in (b) below. The minimwn vnhulle for conduit bodies shall be as calculatcd in (c) below, The provisions of this section shall not apply to tenllinal housings supplied with motors. See Section 430-12. Boxes and conduit bodics enclosing conduclors, size NO.4 or larger, shall also comply willI the provisions of Section 37U-28. (a) Box Volume Calculations. The volwlle of a wiring enclosure (box) shall be the total volwne of the assembled sections, and, where used, the space provided by plaster rings, domed covers, extension rings, etc., that are marked with their volwne in cubic inches or are made from boxes the dimensiolls of which are listed in Table 370-16(a). (1) Standard Boxes. The volumes of standard boxes that are not marked with a cubic inch capacity shall be as given in Table 370-16(a). (2) Other Boxes. Boxcs }()O cubic inch (1640 cu in.) or less, other than those described in Table 370-16(a), and nomnetallic boxes shall be durably and legibly marked by tIle manufacturcr wiUI Uleir cubic inch capacity. Boxes desclibed in Table 370-16(a) Ulat have a larger cubic inch capacity Ulan is designated in the table shall be pennit1ed to have Uleir cubic inch capacity marked as required by this section. (b) Box FII1 Calculations. The volumes in paragraphs (1) through (5) bclow, as applicable, shall be added together. No allowance shall be required for small fittings such as locknuts and bushings. (1) Conductor Fill. Each conductor that originates outside Ule box and tenninates or is spliced within the box shall be counted once, and each conductor that passes through the box without splice or tennination shall be cowlted once. The conductor fiU, in cubic inches, shall be computed using Table 370-16(b). A conductor, no part of which leaves the box, shall not be cowlted. Exception: Where an equipment grounding conducto7' or not overfour.flxture wires smaller than No. J 4, or both, enter a boxfi'Om a domedflXture or similar canopy and terminate within that box, it shall be permitted to omit these conductors.from the calculatiom. (2) Clamp Fill. Where one or more intclllal cable clamps, whether factory or field supplied, are present in the box, a single volwne allowance in accordance with Table 370-16(b) shall be made based on the largest conductor present in the box. No allowance shall be required Ibr a cable connector with its clamping mechanism outside the box. (3) Support Fitting! Fill. Where one or more flXlw'e studs or hickeys are present in the box, a single volwne allowance in accordance with Table 370-16(b) shall be made for each type of lilting based on the largest conductor present in the hox. (4) Device or Equipment Fill. For each yoke or strap containing one or more devices or equipment, a double volwne allowance in accordance with Table 37U-16(b) shall be made for each yoke or strap based on Ule largest conductor cOJ\llected to a devicc(s) or cquipmcnt supported by that yoke or strap. (5) Equipment Grounding Conductor Fill. Where one or more equipment grounding conductors enters a box, a single volwnc allowance in accordance willt Tablc 370-16(b) shall be made bascd on the largest equipment growl<lina conductor present in the box. Where An Additional set of equipment g1'OIInding conductol'8, as pennitted by Section 250-74, Exception No.4, is presenl in Ule box, an additional vohuue allowance sball be made based on the largest cquiplllcnl grounding conductor in I1le additional set. (c) Conduit Bodies. Conduit bodies endosing No.6 conductors or smaller other Ihan short radius conduit bodies as dcscribed in Section 370- 5 shall have a cross-scctional area not less I1lan twice Ule cross-sectional area oftlte largest conduit or tubing to which it is allached. The maximwn number of conductors pennitted shall be the maximwn nwnber pcnnilled by Table 1 of Chapler 9 for the conduit to which it is attached. Conduit bodies shall not cont.-un spliccs, taps, or devices unlcss thcy al.c durably and legibly marked by I1le manufacturer wiUI UICir cubic inch ca)lacity. The maximum number of conductors shaU be computed using the same procedure for similar conductors in otIler than standard boxes. Conduit bodies shaD be supportcd in a rigid and secure manner. Box Dimension. Inches Trade Size or Type ~ K 1 1/4 Round or Oct,,, gon.L1 ~ K 1 1/2 Round or Octagona.! 4 K 2 1/ 8 Round or Octagonal ~ x 1 1/4 Square 4 K 1 1/2 Square 4 K 2 1/8 Square 4 11/16 x 1 1/4 Square 4 1l/1l' x I 1/7 Sqllnr0 4 11/16 x 2 1/8 Square 3 K ;,> " 1 1/2 Device 3 K 2 K 2 Device 3 X 2 x 7 1/4 Device 3 x Z K 2 1/2 Vevic:e 3 x 2 x 2 3/4 Device 3 K 2 K 3 1/2 Device 4 x 7. ] /8 x I 1/ 7. Dav 1 c'- 4 x 2 1/8 K 1 1/8 Dovico 4 x 2 ]/8 x 2 1/8 Uevice 3 3/4 x 2 x 2 1/2 MIl!'lollry B"',/G"ng 3 3/4 K 2 x 3 1/2 MIl!'lonry lIox/Gang '.::--MinilOuIII Jnternal Uepth 1 3/4 Single Cover/Gillig FD--Minimum Interna.! Depth 7 3/B Single Cover/Gang FS--MinilllulII Internal Depth I 3/4 Huitiple Cover IGang J'"j)--.Mi.nilllum internal I>ppth- 2 3/8 Mult.i.pl" Cover/Gang Maximum Numh~r of Conductors. Min. cu. In. No. No. No. No. No. No. No. Cap. 18 16 14 12 10 8 6 i ;; ~;; - _u_-iJ- --'T --- EJ.5 10 8 21.5 14 12 18.0 12 10 21.0 14 12 30.3 20 17 25.5 17 14 79. ') ] I} 16 42.0 28 24 "7. ') ') 4 10.0 6 5 ]0.5 "7 6 ]2.5 8 "7 ILO 9 8 ]8.0 12 10 10.3 6 <; 13.0 A 7 ]4.5 9 8 fi--5--S~~ 1 6 653 10 9 8 7 4 9 8 1 6 3 10 9 8 7 4 15 13 12 10 6 12 11 10 B 5 14 13 11 C) 5 21 10 16 14 8 3 332 1 ') 4 432 ~ ~ 432 6 ') 5 4 2 7 654 2 98163 r-) 4 4 3 2 6 c, ') 4 2 16') 4 2 14.0 9 !J " 6 ') 2 21.0 14 12 10 C) 8 7 13.5 9 "7 6 9 ') 2 18.0 12 10 9 B 7 6 3 1 A. 0 1/' 10 9 A 7 6 3 24. 0 16 13 12 10 9 B