Page 777 - 2018_IRC

POWER AND LIGHTING DISTRIBUTION

interlocked metal tape-type MC cable that is E3908.8.3 Nonmetallic sheathed cable (Type NM). In
listed and identified as an equipment grounding addition to the insulated conductors, the cable shall have
conductor. an insulated, covered, or bare equipment grounding con-
6.3. The metallic sheath or the combined metallic ductor. Equipment grounding conductors shall be sized in
sheath and equipment grounding conductors of accordance with Table E3908.12. (334.108)
the smooth or corrugated tube-type MC cable E3908.9 Equipment fastened in place or connected by
that is listed and identified as an equipment permanent wiring methods. Noncurrent-carrying metal
grounding conductor. [250.118(10)] parts of equipment, raceways and other enclosures, where
7. Other electrically continuous metal raceways and auxil- required to be grounded, shall be grounded by one of the fol-
iary gutters. [250.118(13)] lowing methods: (250.134)
8. Surface metal raceways listed for grounding. 1. By any of the equipment grounding conductors permit-
[250.118(14)] ted by Sections E3908.8 through E3908.8.3.
E3908.8.1 Flexible metal conduit. Flexible metal conduit [250.134(A)]
shall be permitted as an equipment grounding conductor 2. By an equipment grounding conductor contained
where all of the following conditions are met: within the same raceway, cable or cord, or otherwise
run with the circuit conductors. Equipment grounding
1. The conduit is terminated in listed fittings. conductors shall be identified in accordance with Sec-
2. The circuit conductors contained in the conduit are tion E3407.2. [250.134(B)]
protected by overcurrent devices rated at 20 amperes E3908.10 Methods of equipment grounding. Fixtures and
or less. equipment shall be considered grounded where mechanically
3. The size of the conduit does not exceed trade size 1 / . connected to an equipment grounding conductor as specified
1
4
4. The combined length of flexible metal conduit and in Sections E3908.8 through E3908.8.3. Wire type equipment
flexible metallic tubing and liquid-tight flexible grounding conductors shall be sized in accordance with Sec-
metal conduit in the same ground return path does tion E3908.12. (250 Part VII)
not exceed 6 feet (1829 mm). E3908.11 Equipment grounding conductor installation.
Where an equipment grounding conductor consists of a race-
If used to connect equipment where flexibility is neces-
sary to minimize the transmission of vibration from equip- way, cable armor or cable sheath or where such conductor is a
ment or to provide flexibility for equipment that requires wire within a raceway or cable, it shall be installed in accor-
movement after installation, an equipment grounding con- dance with the provisions of this chapter and Chapters 34 and
ductor shall be installed. [250.118(5)] 38 using fittings for joints and terminations approved for
installation with the type of raceway or cable used. All con-
E3908.8.2 Liquid-tight flexible metal conduit. Liquid- nections, joints and fittings shall be made tight using suitable
tight flexible metal conduit shall be permitted as an equip- tools. (250.120)
ment grounding conductor where all of the following con-
ditions are met: E3908.12 Equipment grounding conductor size. Copper,
aluminum and copper-clad aluminum equipment grounding
1. The conduit is terminated in listed fittings. conductors of the wire type shall be not smaller than shown in
1
2. For trade sizes / through / (metric designator 12 Table E3908.12, but they shall not be required to be larger
3
2
8
through 16), the circuit conductors contained in the than the circuit conductors supplying the equipment. Where a
conduit are protected by overcurrent devices rated at raceway or a cable armor or sheath is used as the equipment
20 amperes or less. grounding conductor, as provided in Section E3908.8, it shall
3
1
3. For trade sizes / through 1 / (metric designator 21 comply with Section E3908.4. Where ungrounded conductors
are increased in size from the minimum size that has suffi-
4
4
through 35), the circuit conductors contained in the cient ampacity for the intended installation, wire type equip-
conduit are protected by overcurrent devices rated at ment grounding conductors shall be increased proportionally
not more than 60 amperes and there is no flexible according to the circular mil area of the ungrounded conduc-
metal conduit, flexible metallic tubing, or liquid- tors. [250.122(A) and (B)]
3
tight flexible metal conduit in trade sizes / inch or
8
1 / inch (9.5 mm through 12.7 mm) in the ground E3908.12.1 Multiple circuits. Where a single equipment
2
fault current path. grounding conductor is run with multiple circuits in the
same raceway or cable, it shall be sized for the largest
4. The combined length of flexible metal conduit and overcurrent device protecting conductors in the raceway or
flexible metallic tubing and liquid-tight flexible cable. [250.122(C)]
metal conduit in the same ground return path does
not exceed 6 feet (1829 mm). E3908.13 Continuity and attachment of equipment
grounding conductors to boxes. Where circuit conductors
If used to connect equipment where flexibility is neces- are spliced within a box or terminated on equipment within or
sary to minimize the transmission of vibration from equip- supported by a box, all equipment grounding conductors
ment or to provide flexibility for equipment that requires associated with any of those circuit conductors shall be con-
movement after installation, an equipment grounding con- nected within the box or to the box with devices suitable for
ductor shall be installed. [250.118(6)]
752 2018 INTERNATIONAL RESIDENTIAL CODE ®
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