300.19 Supporting Conductors in Vertical Raceways
Exception: Steel wire armor cable shall be supported at the top of the riser with a cable support that clamps the steel wire armor. A safety device shall be permitted at the lower end of the riser to hold the cable in the event there is slippage of the cable in the wire-armored cable support. Additional wedge-type supports shall be permitted to relieve the strain on the equipment terminals caused by expansion of the cable under load.
Table 300.19(A) Spacings for Conductor Supports
|Conductor Size||Support of Conductors in Vertical Raceways||Conductors|
|Aluminum or Copper-Clad Aluminum||Copper|
|18 AWG through 8 AWG||Not greater than||30||100||30||100|
|6 AWG through 1/0 AWG||Not greater than||60||200||30||100|
|2/0 AWG through 4/0 AWG||Not greater than||55||180||25||80|
|Over 4/0 AWG through 350 kcmil||Not greater than||41||135||18||60|
|Over 350 kcmil through 500 kcmil||Not greater than||36||120||15||50|
|Over 500 kcmil through 750 kcmil||Not greater than||28||95||12||40|
|Over 750 kcmil||Not greater than||26||85||11||35|
- Clamping devices constructed of or employing insulating wedges inserted in the ends of the raceways. Where clamping of insulation does not adequately support the cable, the conductor also shall be clamped.
- Inserting boxes at the required intervals in which insulating supports are installed and secured in an approved manner to withstand the weight of the conductors attached thereto, the boxes being provided with covers.
- In junction boxes, deflecting the cables not less than 90 degrees and carrying them horizontally to a distance not less than twice the diameter of the cable, the cables being carried on two or more insulating supports and additionally secured thereto by tie wires, if desired. Where this method is used, cables shall be supported at intervals not greater than 20 percent of the support spacing in Table 300.19(A).
- Other approved means.