What is THHN Wire?

THHN (Thermoplastic High-heat Resistant, nylon-coated) wire is also known as the building wire. They come in either stranded or solid conductors and can be manufactured with either copper or aluminum. THHN wire is covered in polyvinyl chloride (PVC) insulation with a nylon jacket.

THHN wire is designed with particular insulation material, condition, and temperature rating. It is used for multiple purposes, including control circuits, wiring machine tools, and electrical appliances.

What are THHN Wire Conductors Made of?

THHN cable conductors are made of pure copper. The larger THHN wires come with standard copper conductors. And the THHN that has a smaller diameter, such as 10 AWG (American Wire Gauge) to 14 AWG, has copper conductors that are soft drawn and solid.

What are the Specifications of THHN Wire?

The THHN wire has a thin PVC insulation that is flame-resistant and covered by an abrasion-resistant nylon jacket. This wire is suitable for applications where the temperature will not exceed 90 degrees Celsius in dry and 75 degrees Celsius in wet conditions.

However, you should consider the wire’s ampacity at high ambient temperatures and when bundling cables together in a raceway or conduit.

The maximum voltage rating for the THHN cable is 600 volts. All THHN cables meet the UL 83 standard for safety thermoplastic-insulated wires and cables and the UL 106 standard for safety machine-tool wires and cables. Some THHN cables also have European Restriction of Hazardous Substances (RoHS) Directive approval.

THHN Wire Size Chart

This size chart will help you understand the specifications of THHN wire in a better way.

 

Copper

Aluminum

Wire Gauge Size

60°C (140°F)
NM-B, UF-B

75°C (167°F)
THW, THWN,
SE, USE, XHHW

90°C (194°F)
THWN-2, THHN,
XHHW-2, USE-2

75°C (167°F)
THW, THWN,
SE, USE, XHHW

90°C (194°F)
XHHW-2, THHN,
THWN-2

14

15

20

25

—

—

12

20

25

30

20

25

10

30

35

40

30

35

8

40

50

55

40

45

6

55

65

75

50

55

4

70

85

95

65

75

3

85

100

115

75

85

2

95

115

130

90

100

1

—

130

145

100

115

1/0

—

150

170

120

135

2/0

—

175

195

135

150

3/0

—

200

225

155

175

4/0

—

230

260

180

205

250

—

255

290

205

230

300

—

285

320

230

260

350

—

310

350

250

280

500

—

380

430

310

350

600

—

420

475

340

385

750

—

475

535

385

435

1000

—

545

615

445

500

 

THHN Wires With Different AWGs Used for?

It works like this – The thicker the wire, the smaller the gauge number, the more electricity it can carry, and the more heat it can dissipate.

  1. 1 AWG THHN: It is the thickest size of wire that is commonly used in household electrical wiring. It is also the size of wire that is used in the main electrical service panel and for large appliances, such as dryers and ranges.
  2. 2 AWG THHN: It is the next size down from 1 AWG and is also commonly used in household electrical wiring and main electrical service panel.
  3. 3 AWG THHN: It is typically used for lighting circuits and smaller appliances.
  4. 6 AWG THHN: This AWG is ideal for low-voltage applications, such as doorbells and security systems.
  5. 8 AWG THHN: it is the smallest size of wire that is commonly used in household electrical wiring.
  6. 10 AWG THHN: It can be used in electrical wiring in buildings and other structures because it is strong enough to handle heavy currents but not so thick as to be brittle.
  7. 12 AWG THHN: It is used in applications where a thinner wire is desired, such as in electric vehicles and energy storage devices.
  8. 14 AWG THHN: One of the most common uses for 14 AWG THHN wire is in constructing electrical panels and in-home wiring.
  9. 16 AWG THHN: This wire is typically used in residential and commercial applications, including wiring outlets, switches, fixtures, and HVAC systems.
  10. 18 AWG THHN: This wire is the thickest. It is typically used for projects that require a lot of power. It can also be used for high-voltage projects only if the amperage is low.