THWN or THHN

PVC Insulation, Nylon Jacket, 600 Volts

Application
General purpose wiring in accordance with the National Electrical Code, maximum conductor temperature of 90°C in dry locations and 75°C in wet locations, 600 volts, for installation in conduit or other recognized raceway. Also used for wiring of machine tools (stranded), appliances, and control circuits not exceeding 600 volts.

These conductors have multiple ratings. Depending upon the product application, allowable temperatures are as follows:
● THHN or T90 Nylon- Dry locations not to exceed 90℃
● THWN-2- Wet or dry locations not to exceed 90° C or locations not to exceed 75℃ when exposed to oil
● THWN- Wet locations not to exceed 75℃ or dry locations not to exceed 90° C or locations not to exceed 75℃ when exposed to oil
● TWN75- Wet locations not to exceed 75℃
● MTW- Wet locations or when exposed to oil at temperatures not to exceed 60° C or dry locations not to exceed 90℃ (with ampacity limited to that for 75℃ conductor temperature per NFPA 79)
● AWM- Dry locations not to exceed 105℃ only when rated and used as appliance wiring material

Construction
CU THHN/THWN(-2) conductors are made with soft drawn copper. Sizes 14 through 4/0 AWG use a combination-unilay stranding while 250 kcmil and larger sizes use a compressed copper stranding. The wire is covered with a tough heat and moisture resistant PVC insulation with an overall nylon jacket. Available in black, white, red, blue, purple, green, yellow, orange, brown, and gray. Some colors are subject to economic order quantity.

Standards
● ASTM B3: Annealed or soft copper wires.
● ASTM B8: Concentric Layered Copper Stranded Conductors.
● ASTM B787: 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation.
● UL 83: Wires and cables insulated with thermoplastic material.

Technical Parameter

Conductor		Insulation thickness		Jacket thickness		Approx. weight		Ampacity
AWG/kcmil	No.	mm	mils	mm	mils	kg/km	lb/kft	75℃	90℃
14	1	0.38	15	0.10	4	22	15	15	15
12	1	0.38	15	0.10	4	34	23	20	20
10	1	0.51	20	0.10	4	54	36	30	30
14	7	0.38	15	0.10	4	24	16	15	15
12	7	0.38	15	0.10	4	36	24	20	20
10	7	0.51	20	0.10	4	57	38	30	30
8	7	0.76	30	0.13	5	94	63	50	55
6	7	0.76	30	0.13	5	141	95	65	75
4	7	1.02	40	0.15	6	226	152	85	100
3	7	1.02	40	0.15	6	281	189	100	115
2	7	1.02	40	0.15	6	348	234	115	130
1	19	1.27	50	0.18	7	445	299	130	145
1/0	19	1.27	50	0.18	7	554	372	150	170
2/0	19	1.27	50	0.18	7	688	462	175	195
3/0	19	1.27	50	0.18	7	856	575	200	225
4/0	19	1.27	50	0.18	7	1068	718	230	260
250	37	1.52	60	0.20	8	1266	851	255	290
300	37	1.52	60	0.20	8	1506	1012	285	320
350	37	1.52	60	0.20	8	1747	1174	310	350
400	37	1.52	60	0.20	8	1985	1334	335	380
500	37	1.52	60	0.20	8	2463	1655	380	430
600	61	1.78	70	0.23	9	2957	1987	420	475
750	61	1.78	70	0.23	9	3667	2464	475	535
1000	61	1.78	70	0.23	9	4847	3257	545	615

+Allowable ampacities shown are for general use as specified by the 2014 Edition of the National Electrical Code Sections 310.15 and 240.4(D). Unless the equipment is marked for use at higher temperatures the conductor shall be limited to the following per NEC 110.14(C):
75℃ – When terminated to equipment for circuits rated over 100 amperes or marked for conductors larger than 1 AWG.
90℃ – THHN dry locations and THWN-2 wet or dry locations for ampacity adjustment purposes using NEC section 310.15.