See 300.1(C) for the metric designators and trade sizes. These are for identification purposes only and do not relate to actual dimensions.
344.22 Number of Conductors. The number of conduc- tors shall not exceed that permitted by the percentage fill specified in Table 1, Chapter 9.
Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.
344.24 Bends — How Made. Bends of RMC shall be so made that the conduit will not be damaged and so that the internal diameter of the conduit will not be effectively reduced. The radius of the curve of any field
bend to the centerline of the conduit shall not be less than indicated in Table 2, Chapter 9.
344.26 Bends — Number in One Run. There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes.
344.28 Reaming and Threading. All cut ends shall be reamed or otherwise finished to remove rough edges. Where conduit is threaded in the field, a standard cutting die with a 1 in 16 taper (%-in. taper per foot) shall be used.
FPN: See ANS1/ASME B. 1.20.1-1983, Standard for Pipe
Threads, General Purpose (Inch).
344.30 Securing and Supporting. RMC shall be installed as a complete system in accordance with 300.18 and shall be securely fastened in place and supported in accordance with 344.30(A) and (B) or permitted to be unsupported in accordance with 344.30(C).
(A) Securely Fastened. RMC shall be securely fastened within 900 mm (3 ft) of each outlet box, junction box, device box, cabinet, conduit body, or other conduit termination. Fastening shall be permitted to be increased to a distance of 1.5 m (5 ft) where structural members do not readily permit fastening within 900 mm (3 ft). Where approved, conduit shall not be required to be securely fastened within 900 mm (3 ft) of the service head for above-the-roof termination of a mast.
(B) Supports. RMC shall be supported in accordance with one of the following:
(1) Conduit shall be supported at intervals not exceeding
3 m (10 ft).
(2) The distance between supports for straight runs of con- duit shall be permitted in accordance with Table
344.30(B)(2), provided the conduit is made up with threaded couplings and such supports prevent transmission of stresses to termination where conduit is deflected between supports.
Table 344.30(B)(2) Supports for Rigid Metal Conduit
Maximum Distance
Between Rigid Metal
Conduit Size Conduit Supports
Metric
Designator Trade Size m ft
16-21 '/2-y4 3.0 10
27 i 3.7 12
35-41 l'/4-l'/2 4.3 14
53-63 2-2'/2 4.9 16
78 and 3 and larger 6.1 20
(3) Exposed vertical risers from industrial machinery or fixed equipment shall be permitted to be supported at intervals not exceeding 6 m (20 ft) if the conduit is made up with threaded couplings, the conduit is supported and securely fastened at the top and bottom of the riser, and no