THHN Building Wire

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Building Wire (THHN) and Fixture Wire (TFN/TFFN)

THHN Building Wire

More Building Wire (THHN) and Fixture Wire (TFN/TFFN) Options

THHN Wires in Various Sizes

THHN wire is a very popular type of building wire used in all types of industrial, commercial and residential construction. This type of building wire can be used in damp and dry locations. THHN stands for Thermoplastic High Heat Nylon which is a description of the wires jacket and insulation components. The conductor comes in multiple strands for anything over 10 gauge and is offered in stranded or solid conductor for gauges 14-10.

THHN wire has an advantage as build wire because of its ability to handle up to 600 volts which covers most common appliances. The installation of THHN as building wire will fall within most building codes set out in the list of National Electrical Codes. However, because this wire has a thermoplastic jacket it can release toxic gases when burned and cannot be used outside or buried due to its minimal protection. Because this wire is used in building conditions where very little can hurt it, the jacketing protection is abrasion resistance, but has little else in means of wire protection.

Learn More about THHN Wire in our Blog

TFFN Vs THHN Wire

MTW Vs THHN Wire

THHN Building Wire Specs

THHN Building Wire Applications
RoHS Hook-up Wire RoHS Available — just ask your sales rep for THHN Wire RoHS Certificate!

Interested in THHN Striping? We've got you covered!

Part Number	AWG Size	Conductor Stranding	Nom. O.D. (in)	Nom. Insul. Thick. (in)	Jacket Thick	Approx LBS/MFT	Ampacity @ 90°C
THHN 14 1	14	Solid	0.1020	0.015	0.004	15.00	15
THHN 14 19	14	19/27	0.1090	0.015	0.004	16.00	15
THHN 12 1	12	Solid	0.1190	0.015	0.004	23.00	20
THHN 12 19	12	19/25	0.1280	0.015	0.004	24.00	20
THHN 10 1	10	Solid	0.1610	0.020	0.004	38.00	30
THHN 10 19	10	19/23	0.1610	0.020	0.004	38.00	30
THHN 8 19	8	19/21	0.2130	0.030	0.005	63.00	55
THHN 6 19	6	19/.0372	0.2490	0.030	0.005	95.00	75
THHN 4 19	4	19/.0469	0.3180	0.040	0.006	152.00	95
THHN 3 19	3	19/.0526	0.3460	0.040	0.006	189.00	110
THHN 2 19	2	19/.0591	0.3780	0.040	0.006	234.00	130
THHN 1 19	1	19/.0664	0.4350	0.050	0.007	299.00	150
THHN 1/0 19	1/0	19/.0745	0.4740	0.050	0.007	372.00	170
THHN 2/0 19	2/0	19/.0837	0.5180	0.050	0.007	462.00	195
THHN 3/0 19	3/0	19/.0940	0.5680	0.050	0.007	575.00	225
THHN 4/0 19	4/0	19/.1055	0.6240	0.050	0.007	718.00	260
THHN 250 37	250	37/.0822	0.6780	0.060	0.008	851.00	290
THHN 300 37	300	37/.0822	0.7300	0.060	0.008	1012.00	320
THHN 350 37	350	37/.0973	0.7770	0.060	0.008	1174.00	350
THHN 400 37	400	37	0.8210	0.060	0.008	1334.00	380
THHN 500 37	500	37	0.9020	0.060	0.008	1655.00	430
THHN 600 61	600	61	0.9980	0.070	0.009	1987.00	475
THHN 750 61	750	61	1.1260	0.070	0.009	2464.00	535
THHN 1000 61	1000	61	1.2750	0.070	0.009	1275.00	615

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THHN Wire Applications

THHN electrical wire is meant for use as general-purpose wiring for installation in conduit or other recognized raceway. THHN wire may also be used for machine tool, appliance, and control circuit wiring. Read on below for THHN wire specs.

THHN Wire Approvals:

UL listed Stds. 83 & 1063 as: Type THHN Wire 90°C in dry locations, Type THWN Wire 75°C in wet locations.
A-A-59544, NEMA WC-5, UL-758
CSA approval upon request

THHN Wire Specifications:

Conductor: Bare Copper, Soft Drawn
Insulation: Polyvinylchloride (PVC)
Jacket: Nylon
Standard Colors (denoted by a dash and number code following the part number below): Black (-0), Brown (-1), Red (-2), Orange (-3), Yellow (-4), Green (-5), Blue (-6), Violet (-7), Gray (-8), White (-9), Pink (-10), Tan (-11); Striping and Other colors available upon request.
Gasoline & oil resistant - Type MTW 90°C Machine Tool Wire (stranded only) 105°C AWM, 80°C when exposed to oil.

THHN Wire Ratings:

THHN-THWN: 75°C Oil, 75°C Wet, 90°C Dry, 600V
THWN-2: 75°C Oil, 90°C Wet, 90°C Dry, 600V
MTW: 60°C Oil, 60°C Wet, 90°C Dry, 600V
AWM 1316 to 1321: 80°C Oil, - Wet, 105°C Dry, 600V
AWM 1408 to 1414: 60°C Oil, 60°C Wet, 90°C Dry, 600V
AWM 1452 to 1453: 80°C Oil, - Wet, 90°C Dry, 600V
T90 NYLON: 60°C Oil, - Wet, 90°C Dry, 1000V
TWN 75: - Oil, 75°C Wet, - Dry, 600V

THHN Wire Printing:

14 - 10 AWG (solid conductors): "AWG Type THHN or THWN GASOLINE AND OIL RES II 600V (UL) or AWM VW-1--C-UL Type T90 NYLON or TWN 75 FT-1"
14 AWG - 750 KCMIL (stranded): "AWG Type MTW or THHN or THWN or GASOLINE AND OIL RES II 600V (UL) or AWM--C-UL Type T90 Nylon or TWN 75." "VW-1" and "FT1" on 14 - 6 AWG and "for CT USE SUN RES" on 1/0 AWG and larger in black. THWN-2 on 8 AWG and larger.

Customization Services for THHN Wire include: