Article 326
Integrated Gas Spacer Cable: Type IGS
Part I. General
- Scope. This article covers the use, installation, and construction specifications for integrated gas spacer cable, Type IGS.
- Definition.
Integrated Gas Spacer Cable, Type IGS. A factory assembly of one or more conductors, each individually insulated and enclosed in a loose fit, nonmetallic flexible conduit as an inte‐ grated gas spacer cable rated 0 through 600 volts.
Part II. Installation
326.10 Uses Permitted. Type IGS cable shall be permitted for use underground, including direct burial in the earth, as the following:
- Service-entrance conductors
- Feeder or branch-circuit conductors
- Service conductors, underground
326.12 Uses Not Permitted. Type IGS cable shall not be used as interior wiring or be exposed in contact with buildings.
326.24 Bending Radius. Where the coilable nonmetallic conduit and cable are bent for installation purposes or are flexed or bent during shipment or installation, the radius of the curve of the inner edge measured to the inside of the bend shall not be less than specified in Table 326.24.
326.26 Bends. A run of Type IGS cable between pull boxes or terminations shall not contain more than the equivalent of four quarter bends (360 degrees total), including those bends located immediately at the pull box or terminations.
326.40 Fittings. Terminations and splices for Type IGS cable shall be identified as a type that is suitable for maintaining the gas pressure within the conduit. A valve and cap shall be provi‐ ded for each length of the cable and conduit to check the gas pressure or to inject gas into the conduit.
326.80 Ampacity. The ampacity of Type IGS cable shall not exceed the values shown in Table 326.80.
Part III. Construction Specifications
326.104 Conductors. The conductors shall be solid aluminum rods, laid parallel, consisting of one to nineteen 12.7 mm (1∕2 in.) diameter rods. The minimum conductor size shall be 250 kcmil, and the maximum size shall be 4750 kcmil.
Table 326.24 Minimum Radii of Bends
| Metric Designator | Trade Size | mm | in. | |
| 53 | 2 | 600 | 24 | |
| 78 | 3 | 900 | 35 | |
| 103 | 4 | 1150 | 45 |
Conduit Size Minimum Radii
ARTICLE 328 — MEDIUM VOLTAGE CABLE: TYPE MV 328.30