Is Romex cable in conduit rated for the AC side of an instalaltion that uses Enphase?
Or do I have to use THHN wire in conduit?
Comments
Romex is a generic term for type NM (Non Metallic Sheathing) cable with usually size 12 or 14 wire inside.
Type NM in usually only used in residential construction in dry locations. So, the only place it would be appropriate in solar installations is for an AC circuit running from a sub-roof junction box to a sub or service panel.
NEC
334.10 Uses Permitted.
Type NM, Type NMC, and Type NMS cables shall be permitted to be used in the following:
(1) One- and two-family dwellings.
(2) Multifamily dwellings permitted to be of Types III, IV, and V construction except as prohibited in 334.12.
(3) Other structures permitted to be of Types III, IV, and V construction except as prohibited in 334.12. Cables shall be concealed within walls, floors, or ceilings that provide a thermal barrier of material that has at least a 15-minute finish rating as identified in listings of fire-rated assemblies.
FPN No. 1: Types of building construction and occupancy classifications are defined in NFPA 220-2006, Standard on Types of Building Construction, or the applicable building code, or both.
FPN No. 2: See Annex E for determination of building types [NFPA 220, Table 3-1].
(4) Cable trays in structures permitted to be Types III, IV, or V where the cables are identified for the use.
FPN: See 310.10 for temperature limitation of conductors.
(A) Type NM. Type NM cable shall be permitted as follows:
(1) For both exposed and concealed work in normally dry locations except as prohibited in 334.10(3)
(2) To be installed or fished in air voids in masonry block or tile walls
(B) Type NMC. Type NMC cable shall be permitted as follows:
(1) For both exposed and concealed work in dry, moist, damp, or corrosive locations, except as prohibited by 334.10(3)
(2) In outside and inside walls of masonry block or tile
(3) In a shallow chase in masonry, concrete, or adobe protected against nails or screws by a steel plate at least 1.59 mm ( in.) thick and covered with plaster, adobe, or similar finish
(C) Type NMS. Type NMS cable shall be permitted as follows:
(1) For both exposed and concealed work in normally dry locations except as prohibited by 334.10(3)
(2) To be installed or fished in air voids in masonry block or tile walls
334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:
(1) In any dwelling or structure not specifically permitted in 334.10(1), (2), and (3)
Exception: Type NM, NMC, and NMS cable shall be permitted in Type I and II construction when installed within raceways permitted to be installed in Type I and II construction.
(2) Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings
(3) As service-entrance cable
(4) In commercial garages having hazardous (classified) locations as defined in 511.3
(5) In theaters and similar locations, except where permitted in 518.4(B)
(6) In motion picture studios
(7) In storage battery rooms
(8) In hoistways or on elevators or escalators
(9) Embedded in poured cement, concrete, or aggregate
(10) In hazardous (classified) locations, except where permitted by the following:
a. 501.10(B)(3)
b. 502.10(B)(3)
c. 504.20
(B) Types NM and NMS. Types NM and NMS cables shall not be used under the following conditions or in the following locations:
(1) Where exposed to corrosive fumes or vapors
(2) Where embedded in masonry, concrete, adobe, fill, or plaster
(3) In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish
(4) In wet or damp locations
THWN or THWN-2 is the best wire to use in conduits on the roof for grounded PV installations. Here's a helpful article by John Wiles (Click to link).
Comments
Romex is a generic term for type NM (Non Metallic Sheathing) cable with usually size 12 or 14 wire inside.
Type NM in usually only used in residential construction in dry locations. So, the only place it would be appropriate in solar installations is for an AC circuit running from a sub-roof junction box to a sub or service panel.
NEC
334.10 Uses Permitted.
Type NM, Type NMC, and Type NMS cables shall be permitted to be used in the following:
(1) One- and two-family dwellings.
(2) Multifamily dwellings permitted to be of Types III, IV, and V construction except as prohibited in 334.12.
(3) Other structures permitted to be of Types III, IV, and V construction except as prohibited in 334.12. Cables shall be concealed within walls, floors, or ceilings that provide a thermal barrier of material that has at least a 15-minute finish rating as identified in listings of fire-rated assemblies.
FPN No. 1: Types of building construction and occupancy classifications are defined in NFPA 220-2006, Standard on Types of Building Construction, or the applicable building code, or both.
FPN No. 2: See Annex E for determination of building types [NFPA 220, Table 3-1].
(4) Cable trays in structures permitted to be Types III, IV, or V where the cables are identified for the use.
FPN: See 310.10 for temperature limitation of conductors.
(A) Type NM. Type NM cable shall be permitted as follows:
(1) For both exposed and concealed work in normally dry locations except as prohibited in 334.10(3)
(2) To be installed or fished in air voids in masonry block or tile walls
(B) Type NMC. Type NMC cable shall be permitted as follows:
(1) For both exposed and concealed work in dry, moist, damp, or corrosive locations, except as prohibited by 334.10(3)
(2) In outside and inside walls of masonry block or tile
(3) In a shallow chase in masonry, concrete, or adobe protected against nails or screws by a steel plate at least 1.59 mm ( in.) thick and covered with plaster, adobe, or similar finish
(C) Type NMS. Type NMS cable shall be permitted as follows:
(1) For both exposed and concealed work in normally dry locations except as prohibited by 334.10(3)
(2) To be installed or fished in air voids in masonry block or tile walls
334.12 Uses Not Permitted.
(A) Types NM, NMC, and NMS. Types NM, NMC, and NMS cables shall not be permitted as follows:
(1) In any dwelling or structure not specifically permitted in 334.10(1), (2), and (3)
Exception: Type NM, NMC, and NMS cable shall be permitted in Type I and II construction when installed within raceways permitted to be installed in Type I and II construction.
(2) Exposed in dropped or suspended ceilings in other than one- and two-family and multifamily dwellings
(3) As service-entrance cable
(4) In commercial garages having hazardous (classified) locations as defined in 511.3
(5) In theaters and similar locations, except where permitted in 518.4(B)
(6) In motion picture studios
(7) In storage battery rooms
(8) In hoistways or on elevators or escalators
(9) Embedded in poured cement, concrete, or aggregate
(10) In hazardous (classified) locations, except where permitted by the following:
a. 501.10(B)(3)
b. 502.10(B)(3)
c. 504.20
(B) Types NM and NMS. Types NM and NMS cables shall not be used under the following conditions or in the following locations:
(1) Where exposed to corrosive fumes or vapors
(2) Where embedded in masonry, concrete, adobe, fill, or plaster
(3) In a shallow chase in masonry, concrete, or adobe and covered with plaster, adobe, or similar finish
(4) In wet or damp locations
THWN or THWN-2 is the best wire to use in conduits on the roof for grounded PV installations. Here's a helpful article by John Wiles (Click to link).