Professional cable manufacturer
UL 44 · XLPE · 600 V / 1000 V · +90°C wet · rooftop adder exempt
XHHW-2 Copper Building Wire
XLPE-insulated thermoset building wire rated 90°C in wet locations and exempt from the 33°C rooftop temperature adder — for feeders, service runs and rooftop circuits in commercial and industrial work.
600V
Rated voltage
+90°C wet
Thermoset XLPE
XLPE
Single-layer wall
−40°C
Cold bend
UL 44 / XHHW-2 NEC 310.15(B)(2) exempt 1000 V from 8 AWG Sample orders available
XHHW-2 BUILDING WIRE · XLPE
UL 44thermoset-insulated wire
XLPEcross-linked polyethylene
600 / 1000 V1000 V from 8 AWG
+90°C wetdry and wet locations
NEC 310.15(B)(2)no rooftop adder
Key Specifications
The essentials, at a glance
The numbers an electrical contractor checks before the wire goes on the truck — and the one clause most datasheets leave out.
600V
Rated voltage, all sizes
+90°C wet
Thermoset, dry and wet
XLPE
Single-layer insulation
55 A
8 AWG, NEC 310.16 90°C
2.06
8 AWG, Ω/km at 20°C
No +33°C
Rooftop adder exempt
Product Overview
The building wire that is rated 90°C wet
XHHW-2 is a single-conductor, thermoset-insulated building wire made to UL 44. The insulation is cross-linked polyethylene — not PVC — and the -2 suffix is the whole point: it means the wire carries +90°C in wet locations, not the +75°C that plain XHHW is limited to. One spool therefore covers a wet raceway, a wash-down area and a rooftop without changing the specification.
Because the insulation is a single extruded layer of XLPE, there is no nylon jacket to add and no PVC to keep dry. At 8 AWG the wall is 1.14 mm (45 mil) and the finished conductor measures 6.05 mm overall — still a little larger than the equivalent THHN at about 5.6 mm, because here the XLPE wall carries the whole dielectric duty instead of sharing it with a nylon cover.
The clause that sells this wire in North America is NEC 310.15(B)(2). Where a raceway or cable runs less than 23 mm above a roof and is exposed to direct sunlight, the code adds 33°C (60°F) to the outdoor design temperature before the ampacity correction is applied. The exception reads, in full: “Type XHHW-2 insulated conductors shall not be subject to this ampacity adjustment.” A rooftop feeder in a 40 mm conduit in Phoenix is a different cable at 33°C of adder — XHHW-2 removes the adder, not the sunlight.
Ampacity comes from NEC Table 310.16: 55 A for 8 AWG at the 90°C column, 50 A at 75°C. The 90°C column is still subject to NEC 110.14(C) — the conductor ampacity may not exceed the lowest temperature rating of any connected termination or device, so on 75°C lugs the practical circuit is 50 A. What the 90°C rating buys is headroom for ambient correction and conduit fill, which is exactly where a rooftop or a bundled pull runs out of ampacity first.
Voltage is 600 V across the range. The 1000 V rating exists from 8 AWG and larger, and it is not automatic: UL 44 permits it, but each manufacturer must be listed and marked for it. We state 1000 V only where the listing for that size carries it, and we say so on the quotation rather than on a picture of the wire.
More about the manufacturer: About SORIVO →
Key Features
Eight things that decide an XHHW-2 order
UL 44, not UL 83
UL 44 covers thermoset-insulated wire — XLPE, EPR and the RHH / RHW family. UL 83 covers thermoplastic (THHN / THWN-2). The two standards are not interchangeable, and an inspector reads the print, not the colour of the insulation.
-2 Means Wet 90°C
Plain XHHW is 90°C dry but only 75°C in a wet location. The -2 suffix lifts the wet rating to 90°C, which is what makes the wire usable in a wet raceway at full ampacity instead of derated.
Rooftop Adder Exempt
NEC 310.15(B)(2) adds 33°C for a raceway less than 23 mm above a sun-exposed roof. The exception for Type XHHW-2 removes that adder — the single most useful line in this datasheet for anyone building on a roof.
Single-Layer XLPE
One extruded wall of cross-linked polyethylene, 1.14 mm at 8 AWG. No nylon cover, no PVC, nothing to delaminate. XLPE also holds its shape under a lug at 90°C where PVC softens.
1000 V from 8 AWG
UL 44 ranges to 1000 V, 2000 V and 5000 V, but the 1000 V XHHW-2 listing starts at 8 AWG and is not held by every maker. We quote 1000 V only where the size we ship is marked for it.
SIS and RW90 Available
The same construction is commonly dual-listed as SIS for switchboard and panel wiring and as RW90 for Canadian projects. Useful when one wire has to serve the panel shop and the field; confirm the print legend per order.
−40°C Cold Bend
Cold bend tested to −40°C on the XLPE wall, and sunlight-resistant marking available. That covers an outdoor laydown yard in winter without a separate cold-weather product.
Larger OD Than THHN
6.05 mm overall at 8 AWG against about 5.6 mm for THHN — the XLPE wall is thicker because it is the only wall, while THHN splits the same dielectric duty between PVC and a thin nylon cover. Check conduit fill against the real diameter, not the trade size, when swapping one for the other.
Applications
Where XHHW-2 earns its price
Anywhere the wire will be wet, hot, or above a roof — which is most of a modern commercial job.
01
Service and Feeder Runs
Service-entrance and feeder conductors in conduit, sized on the 75°C column and corrected upward on the 90°C column where ambient demands it.
02
Rooftop Raceways
The classic case: a run under 23 mm above a sun-exposed roof, where THHN / THWN-2 takes a 33°C adder and XHHW-2 does not.
03
Rooftop PV DC Circuits
PV source and output circuits in conduit on a membrane roof, where the ambient correction usually decides the conductor size before ampacity does.
04
Wet and Wash-Down Areas
Food plants, car washes, pump rooms and cooling-tower decks — wet-location work at 90°C rather than a derated 75°C.
05
Switchboards and Panel Shops
The SIS listing covers panel and switchboard internal wiring, so the same spool serves the shop and the field.
06
Cold-Climate Outdoor Work
−40°C cold bend lets the wire be pulled and dressed outdoors in winter without cracking the insulation at a bend.
07
Industrial Plants
Machine rooms, compressor buildings and process areas where oil, heat and moisture occur together and PVC is the weak link.
08
Retrofit Pulls
Rewires in existing conduit where a slightly smaller overall diameter and a slick XLPE surface reduce pulling tension on long runs.
Technical Specifications
Full specification sheet
The complete parameter set — the same data our engineers quote from.
Table 1 Dimensions, weight, resistance and ampacity, copper 8 AWG – 4/0
| AWG size | Strands count | Conductor dia. mm (in) | XLPE insulation mm (in) | Overall dia. mm (in) | Weight lb/1000 ft (kg/km) | DC resistance 20°C calc., Ω/km | Ampacity 75°C, A | Ampacity 90°C, A |
|---|---|---|---|---|---|---|---|---|
| 8 | 7 | 3.58 (0.141) | 1.14 (0.045) | 6.05 (0.238) | 64 (95) | 2.06 | 50 | 55 |
| 6 | 7 | 4.50 (0.177) | 1.14 (0.045) | 6.96 (0.274) | 97 (144) | 1.30 | 65 | 75 |
| 4 | 7 | 5.72 (0.225) | 1.14 (0.045) | 8.15 (0.321) | 148 (220) | 0.815 | 85 | 95 |
| 3 | 7 | 6.40 (0.252) | 1.14 (0.045) | 8.84 (0.348) | 184 (274) | 0.646 | 100 | 115 |
| 2 | 7 | 7.16 (0.282) | 1.14 (0.045) | 9.63 (0.379) | 228 (339) | 0.513 | 115 | 130 |
| 1 | 19 | 8.18 (0.322) | 1.40 (0.055) | 11.05 (0.435) | 291 (433) | 0.407 | 130 | 145 |
| 1/0 | 19 | 9.17 (0.361) | 1.40 (0.055) | 12.09 (0.476) | 361 (537) | 0.322 | 150 | 170 |
| 2/0 | 19 | 10.29 (0.405) | 1.40 (0.055) | 13.21 (0.520) | 450 (670) | 0.256 | 175 | 195 |
| 3/0 | 19 | 11.58 (0.456) | 1.40 (0.055) | 14.58 (0.574) | 564 (839) | 0.203 | 200 | 225 |
| 4/0 | 19 | 13.00 (0.512) | 1.40 (0.055) | 16.00 (0.630) | 707 (1052) | 0.161 | 230 | 260 |
The highlighted 8 AWG row is the size most often specified. Insulation walls follow the thicknesses printed in NEC Table 310.4(A) — 45 mil to 2 AWG and 55 mil to 4/0. Dimensions and weights are the manufacturer's published values for a Class B compressed stranded XLPE construction and are nominal; they are not a substitute for the drawing on a live order. The resistance column is a calculated value from ideal copper resistivity over the nominal cross-section — it is not the NEC Chapter 9 Table 8 figure, which is listed at 75 °C. Sizes 14, 12 and 10 AWG are made in the same construction and are quoted with their dimensions rather than tabulated here. Ampacity is NEC Table 310.16 for not more than three current-carrying conductors in a raceway or cable at 30°C ambient, and remains subject to NEC 110.14(C). Sizes above 4/0 are quoted from the same range up to 1000 kcmil — we quote them, and confirm the dimensions on the drawing rather than extrapolating them here.
Table 2 Construction and performance parameters
| General Information | |
| Product Name | XHHW-2 Copper Building Wire, XLPE insulated |
| Product Type | Thermoset-insulated, single-conductor building wire |
| Size Range | 14 AWG – 4/0 AWG (copper); quoted to 1000 kcmil on request |
| Primary Standard | UL 44 — thermoset-insulated wires and cables |
| Further Standards | ASTM B3 and ASTM B8 (conductor); ASTM B787 for the compact unilay strand; CSA C22.2 No. 38 for the RW90 listing where dual-listed |
| Certification | UL 44 / XHHW-2 — scope confirmed against the certificate for the selected size. 1000 V marking applies from 8 AWG and is not held by every manufacturer. |
| Rated Voltage | 600 V (all sizes); 1000 V from 8 AWG where the listing carries it |
| Conductor | |
| Conductor Material | Soft annealed bare copper |
| Stranding | Class B compressed stranded to ASTM B8 — 7-strand to 2 AWG, 19-strand from 1 AWG. Flexible stranding to ASTM B787 available for SIS and panel work. |
| Conductor Diameter (8 AWG) | 3.58 mm (0.141 in), 7-strand Class B |
| Max. DC Resistance @20°C, calculated (8 AWG) | 2.06 Ω/km — ideal copper resistivity over the 8.37 mm² nominal cross-section |
| Insulation | |
| Insulation Material | XLPE — cross-linked polyethylene, thermoset |
| Insulation Thickness (8 AWG) | 1.14 mm (0.045 in) |
| Overall Diameter (8 AWG) | 6.05 mm (0.238 in) |
| Weight (8 AWG) | ≈ 64 lb/1000 ft (≈ 95 kg/km) |
| Available Colours | Black, white, red, blue, green, yellow, gray, brown, orange, violet — to order |
| Colour Rules | Green for equipment grounding, white or gray for the grounded conductor, per NEC 250.119 and 200.6 |
| Electrical Ratings | |
| Ampacity (NEC 310.16) | 8 AWG: 50 A at 75°C / 55 A at 90°C — not more than three current-carrying conductors in a raceway or cable, 30°C ambient |
| Termination Limit | NEC 110.14(C) — conductor ampacity may not exceed the lowest temperature rating of any connected termination, conductor or device. On 75°C lugs, 8 AWG is a 50 A conductor. |
| Rooftop | NEC 310.15(B)(2) Exception — Type XHHW-2 conductors are not subject to the 33°C rooftop temperature adder |
| Use of the 90°C Column | Permitted for ampacity adjustment and correction, and for the ambient correction that a rooftop or a hot raceway demands |
| Temperature & Environmental | |
| Temperature Rating | +90°C dry and +90°C wet (the “-2” rating); emergency overload 130°C and short circuit 250°C are typical thermoset values |
| Cold Bend | −40°C |
| Sunlight Resistance | Sunlight-resistant marking available; confirm per size on the print legend |
| Moisture Resistance | Wet-location rated through the XHHW-2 designation |
| Oil Resistance | Gasoline and oil resistant II where marked — confirm for the construction ordered |
| Direct Burial | Not listed for direct burial — use a raceway, or specify a USE / USE-2 or UF cable |
| Tray Ratings | CT and FT4 ratings are size-dependent (typically 1/0 AWG and above) and are not claimed across the range |
| Packaging & Logistics | |
| Packaging | Spool / coil / reel |
| Standard Lengths | 100 ft / 500 ft / 1000 ft per spool |
| MOQ | 1 spool (sample order available) |
| Lead Time | 5–15 working days (stock sizes 3–5 days) |
Final selection should be based on circuit loading, overcurrent protection, ambient temperature, conduit fill, voltage drop and the temperature rating of the terminations actually used. Send us the circuit and we will confirm the size against the code edition your inspector works to.
Certificates & Standards
Verify before you buy — we make it easy
UL 44 / XHHW-2
UL 44 is the thermoset standard; XHHW-2 is the listing that carries 90°C in wet locations. Certificate of conformity available on request.
Request certificate copy →CSA C22.2 No. 38 (RW90)
The Canadian thermoset standard. Where the construction is dual-listed, the same wire ships as RW90 for CSA-specified projects.
Request test report →Sunlight, Cold Bend, RoHS
Sunlight-resistant marking and −40°C cold bend are listed per size, not across the family; RoHS compliance applies throughout.
Request test report →Transparency note: certification status and exact scope should always be confirmed against the certificate for the selected wire construction and size. We send the certificate with the quotation rather than describing it on this page.
Quality & Factory
Made in a real cable factory, tested before it ships
Every spool of XHHW-2 is extruded, cross-linked and released against the applicable UL 44 requirements.
- 1Incoming material control — copper rod and XLPE compound are checked before the line starts; cross-linking is a chemical process and the compound batch decides the result.
- 2In-line process monitoring — strand count, conductor diameter, insulation concentricity and wall thickness are tracked through extrusion and curing.
- 3Routine electrical tests — spark test on line, then finished-wire voltage, insulation resistance and conductor resistance against 2.06 Ω/km at 8 AWG.
- 4Batch documentation — conductor resistance, wall thickness, colour and test records are retained for every production batch.
19+
countries served
60+
building & industrial projects
100%
routine test before shipment
How to Order
From inquiry to loaded spool in 5 steps
Send Inquiry
Tell us the size, colour, quantity, the code edition the project is built to, and whether the run is on a roof.
Confirm Construction
We confirm the stranding, the wall thickness, whether 1000 V marking applies to that size, and the quotation — within one working day.
Sample Evaluation
Sample for qualification; stock sizes usually leave from existing spools within a few working days.
Bulk Production
5–15 working days lead time, with batch test documentation.
Delivery & Support
Spool, coil or reel packing, export documents, and after-sales support on installation questions.
FAQ
Questions buyers ask before ordering
The wet-location temperature. XHHW is rated 90°C in dry and damp locations but only 75°C in a wet location. XHHW-2 is rated 90°C in both dry and wet locations. Same XLPE insulation family, different listing — and the difference decides whether a wet raceway runs at full ampacity or derated. We supply XHHW-2, so the question does not arise on delivery.
Both are 600 V single-conductor building wires; the insulation systems are different. THHN / THWN-2 is thermoplastic PVC under a nylon jacket, rated 90°C dry and 90°C wet as THWN-2, and it is usually the cheaper wire. XHHW-2 is thermoset XLPE, rated 90°C dry and wet, resistant to the 33°C rooftop adder under NEC 310.15(B)(2), and better at holding shape under a lug at temperature. On a dry indoor run THHN is the economical answer; on a roof, in a wash-down area, or where the ambient correction is tight, XHHW-2 is the one that sizes smaller.
Because 33°C of adder changes the answer. NEC 310.15(B)(2) requires the outdoor design temperature to be increased by 33°C for a raceway or cable less than 23 mm above a roof exposed to direct sunlight, before the ambient correction factor is applied. In a hot climate that can push the effective ambient past 70°C and force a conductor two sizes larger. The exception for Type XHHW-2 removes the adder entirely — it does not remove the sunlight, the roof temperature or the need to support the raceway.
Not for the circuit rating. NEC 110.14(C) limits the conductor ampacity to the lowest temperature rating of any connected termination, conductor or device, and most breakers rated 100 A or less are marked 75°C. What the 90°C column is for is adjustment and correction: conduit fill, ambient, and the rooftop calculation above. The corrected value may not exceed the column that matches the terminations — which is why the practical rating of 8 AWG XHHW-2 is 50 A, not 55 A.
No. The 1000 V XHHW-2 rating starts at 8 AWG and, more importantly, it depends on the manufacturer being UL listed and marked for it. UL 44 itself ranges to 1000 V, 2000 V and 5000 V, but a listing is per construction and per size. We confirm the 1000 V marking in writing for the size you order, and we do not print it on a page as though it applied to the whole range.
No. XHHW-2 is a wet-location building wire for raceway and cable tray, not a direct-burial product. For a buried run specify a USE or USE-2 conductor, a UF cable, or a jacketed assembly listed for direct burial. Running XHHW-2 in conduit underground is fine — the conduit is what makes it a raceway installation.
SIS is switchboard wire, used for internal wiring of switchboards and panelboards. XLPE 90°C constructions are commonly dual-listed as XHHW-2 and SIS, and often as RW90 for Canada, because the insulation system already meets all three. It matters commercially: one spool can serve the panel shop and the field, and one test certificate covers both.
Start from the load and the overcurrent device, then correct for ambient and conduit fill using the 90°C column, then cap the result at the termination rating. That sequence is what the code requires and it is why two engineers can reach different answers on the same drawing. Send us the load in amperes or kVA, the run length, the ambient and the termination rating, and we will return the size and the arithmetic.
Need a sample of XHHW-2 for your project?
Tell us the size, colour and quantity — we reply within one working day.
Get a Free Quote
Send your XHHW-2 requirement
The more detail you give, the faster and more accurate our quotation. Our engineers reply within one working day.
- Size (14 AWG – 4/0, or kcmil) and quantity in ft or m
- Voltage class: 600 V, or 1000 V if the size requires it
- Colour, and whether green / white are needed as EGC and neutral
- Installation: raceway, tray, wet location, or rooftop run
- Destination market (US, Canada or other) and code edition, if specified
Inquiry received
Thanks — our engineers will reply within one working day.
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