Article 328
Medium Voltage Cable: Type MV
Table 326.80 Ampacity of Type IGS Cable
| Size (kcmil) | Amperes | Size (kcmil) | Amperes |
| 250 | 119 | 2500 | 376 |
| 500 | 168 | 3000 | 412 |
| 750 | 206 | 3250 | 429 |
| 1000 | 238 | 3500 | 445 |
| 1250 | 266 | 3750 | 461 |
| 1500 | 292 | 4000 | 476 |
| 1750 | 315 | 4250 | 491 |
| 2000 | 336 | 4500 | 505 |
| 2250 | 357 | 4750 | 519 |
326.112 Insulation. The insulation shall be dry kraft paper tapes and a pressurized sulfur hexafluoride gas (SF6), both approved for electrical use. The nominal gas pressure shall be 138 kPa gauge (20 lb/in.2 gauge). The thickness of the paper spacer shall be as specified in Table 326.112.
326.116 Conduit. The conduit shall be a medium density polyethylene identified as suitable for use with natural gas rated pipe in metric designator 53, 78, or 103 (trade size 2, 3, or 4). The percent fill dimensions for the conduit are shown in Table 326.116.
The size of the conduit permitted for each conductor size shall be calculated for a percent fill not to exceed those found in Table 1, Chapter 9.
326.120 Marking. The cable shall be marked in accordance with 310.120(A), 310.120(B)(1), and 310.120(D).
Table 326.112 Paper Spacer Thickness
| Thickness | |||
| Size (kcmil) | mm | in. | |
| 250–1000 | 1.02 | 0.040 | |
| 1250–4750 | 1.52 | 0.060 |
Table 326.116 Conduit Dimensions
Part I. General
- Scope. This article covers the use, installation, and construction specifications for medium voltage cable, Type MV.
- Definition.
Medium Voltage Cable, Type MV. A single or multiconductor solid dielectric insulated cable rated 2001 volts or higher.
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328.6 Listing Requirements. Type MV cables and associated fittings shall be listed.
Part II. Installation
328.10 Uses Permitted. Type MV cable shall be permitted for use on power systems rated up to and including 35,000 volts, nominal, as follows:
- In wet or dry locations.
- In raceways.
- In cable trays, where identified for the use, in accordance with 392.10, 392.20(B), (C), and (D), 392.22(C), 392.30(B)(1), 392.46, 392.56, and 392.60. Type MV cable that has an overall metallic sheath or armor, complies with the requirements for Type MC cable, and is identi‐ fied as “MV or MC” shall be permitted to be installed in cable trays in accordance with 392.10(B)(2).
- Direct buried in accordance with 300.50.
- In messenger-supported wiring in accordance with Part II of Article 396.
- As exposed runs in accordance with 300.37. Type MV cable that has an overall metallic sheath or armor, complies with the requirements for Type MC cable, and is identified as “MV or MC” shall be permitted to be instal‐ led as exposed runs of metal-clad cable in accordance with 300.37.
Informational Note: The “Uses Permitted” is not an all-inclusive list.
328.12 Uses Not Permitted. Type MV cable shall not be used where exposed to direct sunlight, unless identified for the use.
328.14 Installation. Type MV cable shall be installed, termina‐ ted, and tested by qualified persons.
Informational Note: Information about accepted industry prac‐ tices and installation procedures for medium-voltage cable are described in ANSI/NECA/NCSCB 600-2014, Standard for Instal‐ ling and Maintaining Medium-Voltage Cable and in IEEE 576-2000,
Conduit Size
Actual Outside Diameter
Actual Inside Diameter
Recommended Practice for Installation, Termination, and Testing of Insulated Power Cables as Used in Industrial and Commercial Applica‐ tions .
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| Metric Designator | Trade Size | mm | in. | mm | in. | |
| 53 | 2 | 60 | 2.375 | 49.46 | 1.947 | |
| 78 | 3 | 89 | 3.500 | 73.30 | 2.886 | |
| 103 | 4 | 114 | 4.500 | 94.23 | 3.710 |
328.30 Support. Type MV cable terminated in equipment or installed in pull boxes or vaults shall be secured and supported by metallic or nonmetallic supports suitable to withstand the weight by cable ties listed and identified for securement and support, or other approved means, at intervals not exceeding
1.5 m (5 ft) from terminations or a maximum of 1.8 m (6 ft) between supports.
328.80 ARTICLE 330 — METAL-CLAD CABLE: TYPE MC
328.80 Ampacity. The ampacity of Type MV cable shall be determined in accordance with 310.60. The ampacity of Type MV cable installed in cable tray shall be determined in accordance with 392.80(B).
Part III. Construction Specifications
328.100 Construction. Type MV cables shall have copper, aluminum, or copper-clad aluminum conductors and shall comply with Table 310.104(C) and Table 310.104(D) or Table 310.104(E).