On large construction sites, electricity serves as the lifeblood that powers everything from towering cranes to welding operations. Reliable power supply is essential, and at the heart of this system lies durable wiring capable of handling demanding electrical loads. The THHN 250mm² wire represents a specialized solution designed specifically for these high-power applications.
Product Overview
THHN (Thermoplastic High Heat-resistant Nylon-coated) wire is a versatile building wire that complies with the National Electrical Code (NEC) standards, suitable for various electrical applications. The 250mm² specification of THHN wire stands out for its exceptional current-carrying capacity and durability, making it an ideal choice for large-scale construction projects, industrial facilities, and other high-power scenarios. This wiring solution not only ensures safe and reliable power transmission but also withstands challenging environmental conditions.
Applications
THHN wire serves multiple purposes across different sectors:
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New construction and renovation projects:
Functions as main or branch circuits to provide power distribution throughout buildings.
-
Industrial equipment:
Delivers reliable electrical connections for motors, transformers, and switchboards.
-
Control panels:
Facilitates power transmission and signal connections within automated control systems.
-
Machine tools:
Provides electrical supply for various machining equipment.
-
High-power appliances:
Supports energy demands for air conditioning units, ovens, and similar household devices.
Standards and Certifications
THHN wire meets several critical safety and reliability standards:
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UL 83:
Underwriters Laboratories standard covering thermoplastic-insulated wires and cables.
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NEC (National Electrical Code):
The benchmark for safe electrical installation practices in the United States.
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NFPA 79:
National Fire Protection Association standard for industrial machinery electrical systems.
Structural Composition
Conductor
Utilizing annealed bare copper, the conductor provides excellent electrical conductivity. The stranding process enhances flexibility, simplifying installation in applications requiring frequent bending or vibration resistance.
Insulation
The PVC insulation layer offers:
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Superior electrical insulation properties
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Heat resistance up to 90°C in dry environments
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Moderate chemical resistance for extended service life
Jacket
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Enhanced mechanical protection against abrasion
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Improved resistance to oils and solvents
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Reduced surface friction for easier conduit installation
Technical Specifications
|
Cross-Section (mm²)
|
AWG/MCM Equivalent
|
Stranding (No. x mm)
|
Insulation Thickness (mm)
|
Nylon Jacket Thickness (mm)
|
Approx. Diameter (mm)
|
Approx. Weight (kg/km)
|
Ampacity (75°C)
|
|
2.0
|
14
|
7x0.6
|
0.4
|
0.1
|
2.8
|
23.57
|
20
|
|
3.5
|
12
|
7x0.8
|
0.4
|
0.1
|
3.4
|
39.29
|
25
|
|
5.5
|
10
|
7x1.0
|
0.5
|
0.1
|
4.2
|
60.93
|
35
|
|
8.0
|
8
|
7x1.2
|
0.8
|
0.13
|
5.46
|
92.49
|
50
|
|
14
|
6
|
7x1.6
|
0.8
|
0.13
|
6.66
|
155.06
|
65
|
|
22
|
4
|
7x2.0
|
1.0
|
0.15
|
8.3
|
241.69
|
85
|
|
30
|
2
|
7x2.3
|
1.0
|
0.15
|
9.2
|
312.5
|
115
|
|
38
|
1-19
|
19x1.6
|
1.3
|
0.18
|
10.96
|
400.37
|
130
|
|
50
|
1/0-19
|
19x1.8
|
1.3
|
0.18
|
11.96
|
514.96
|
150
|
|
60
|
2/0-19
|
19x2.0
|
1.3
|
0.18
|
12.96
|
626.12
|
175
|
|
80
|
3/0-19
|
19x2.3
|
1.3
|
0.18
|
14.46
|
813.86
|
200
|
|
100
|
4/0-19
|
19x2.6
|
1.3
|
0.18
|
15.96
|
1026.25
|
230
|
|
125
|
250mcm
|
37x2.1
|
1.6
|
0.18
|
18.26
|
1313.25
|
255
|
|
150
|
300mcm
|
37x2.3
|
1.6
|
0.2
|
19.7
|
1561.19
|
285
|
|
200
|
400mcm
|
37x2.6
|
1.6
|
0.2
|
21.8
|
1971.93
|
335
|
|
250
|
500mcm
|
61x2.3
|
1.6
|
0.2
|
24.3
|
2526.66
|
380
|
|
325
|
650mcm
|
61x2.6
|
1.8
|
0.23
|
27.46
|
3219.48
|
435
|
|
400
|
800mcm
|
61x2.9
|
1.8
|
0.23
|
30.16
|
3974.06
|
490
|
|
500
|
1000mcm
|
61x3.2
|
1.8
|
0.23
|
32.86
|
4807.12
|
545
|
Color Coding
THHN wires are available in multiple color options for easy circuit identification and management. Standard colors include black, white, red, green, yellow, blue, and green/yellow combinations. These color codes help prevent wiring errors—black typically indicates hot wires, white represents neutral conductors, while green identifies grounding wires.
Installation Guidelines
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Selecting appropriate wire gauge based on electrical load requirements
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Using professional-grade tools for stripping and termination
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Ensuring all connections remain secure to prevent loosening
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Adhering to local electrical codes and regulations
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Avoiding excessive bending that could compromise insulation integrity
THHN vs. MTW Comparison
While THHN wire sometimes serves as MTW (Machine Tool Wire), key differences exist in their temperature ratings. As THHN, the wire operates at up to 90°C in dry or damp locations and 75°C when exposed to oils or coolants. When designated as MTW, the temperature rating reduces to 60°C in wet conditions or oil exposure. MTW wiring primarily finds application in control panels, machine tools, and appliance interiors.
Conclusion
The THHN 250mm² wire delivers exceptional performance, reliability, and safety for demanding electrical applications. From construction sites to industrial facilities, this wiring solution ensures stable power transmission across various operating conditions. Its robust construction and compliance with industry standards make it a dependable choice for professionals requiring high-capacity electrical distribution.
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