010630-000000-0000001 Scope
1.1 These requirements cover all-thermoplastic Type MTW, 600-V, machine-tool wires and cables for use as specified in the National Electrical Code (NFPA 70), and in the National Fire Protection Association Electrical Standard for Industrial Machinery (NFPA 79). These wires and cables comply with a flame test and are for use at 90 °C (194 °F) and lower temperatures in dry locations and at 60 °C (140 °F) and lower temperatures where exposed to moisture, oil, or coolants such as cutting oils and the like.
1.2 The two single-conductor constructions covered are described in . Both are PVC-insulated and one includes a nylon jacket over the insulation. These single-conductor constructions may be optionally shielded and jacketed. The multiple-conductor constructions covered consist of assemblies of these single-conductor constructions (sizes and styles may be mixed) enclosed by a PVC jacket.
Table 1.1 Single-Conductor Constructions
Conductora size
AWG or kcmil
NEC Construction A
(Nylon jacket not used)
NEC Construction B
Minimum average thickness of the insulation
Minimum thickness of any point of the insulation
Minimum average thickness of the insulation
Minimum thickness of any point of the insulation
Minimum thickness of any point of nylon jacket
Mils
(mm)
Mils
(mm)
Mils
(mm)
Mils
(mm)
Mils
(mm)
22, 7-strand only; 21 – 12
30
(0.76)
27
(0.69)
15
(0.38)
13
(0.33)
4
(0.10)
11 – 10
30
(0.76)
27
(0.69)
20
(0.51)
18
(0.46)
4
(0.10)
9, 8
45
(1.14)
40
(1.02)
30
(0.76)
27
(0.69)
5
(0.13)
7, 6
60
(1.52)
54
(1.37)
30
(0.76)
27
(0.69)
5
(0.13)
5 – 2
60
(1.52)
54
(1.37)
40
(1.02)
36
(0.91)
6
(0.15)
1 – 4/0
80
(2.03)
72
(1.83)
50
(1.27)
45
(1.14)
7
(0.18)
250 – 500
95
(2.41)
86
(2.18)
60
(1.52)
54
(1.37)
8
(0.20)
550 – 1000
110
(2.79)
99
(2.51)
70
(1.78)
63
(1.60)
9
(0.23)
a A conductor is appropriate for use with a cross-sectional area that does not correspond to one of the AWG or kcmil sizes in when the finished wire or cable complies with the marking requirement in 2 and with each of the following:
a) The conductor shall have a DC resistance that is not larger than the resistance determined by interpolation (by cross-sectional area) between the resistances of the next larger and smaller sizes shown in the applicable or .
b) The number of strands, the thicknesses of insulation, the thickness of any nylon jacket, and other particulars shall comply with the requirements applicable to the next smaller size shown in .