4/0 AWG XHHW-2 Stranded Copper Building Wire

XHHW-2 is single-conductor building wire with cross-linked polyethylene (XLPE) insulation, which is where the "X" in its name comes from. "HHW" stands for high heat and water resistance, and "-2" means it's rated 90°C in wet locations as well as dry. 4/0 AWG copper XHHW-2 is installed in conduit or other NEC-recognized raceways at up to 600V and is rated 230A at 75°C. It's used for 225A feeders and panelboards, 250A home services, long 200A runs, and motor and chiller feeders.

Both use cross-linked polyethylene (XLPE) insulation and are rated 600V. The difference is the wet rating. XHHW is rated 90°C in dry locations but only 75°C in wet locations. XHHW-2 is rated 90°C in both, and it passes stricter UL 44 moisture testing. XHHW-2 can be used anywhere XHHW is allowed.

Both THHN/THWN-2 and XHHW-2 are 600V building wires rated 90°C in wet and dry locations, so the real difference is the insulation. THHN/THWN-2 has thin PVC insulation with a nylon jacket. XHHW-2 has a single, thicker layer of cross-linked polyethylene (XLPE), a thermoset material that doesn't melt. XHHW-2 holds up better to abrasion, moisture, and cold. THHN/THWN-2 has a smaller diameter, so more conductors fit in the same conduit, and it usually costs less.

Yes, with room to spare. 4/0 copper is rated 230A at 75°C, which covers 200A in any application. For a 200A home service, 2/0 copper is the minimum under NEC 310.12, so 4/0 copper is usually chosen for commercial 200A circuits, long runs where voltage drop matters, or future load growth.

Not directly. XHHW-2 is not rated for direct burial, so it can't go in a trench without conduit. It can be installed underground inside conduit, because underground raceways are wet locations and XHHW-2 is rated 90°C wet. For burial without conduit, use a direct burial cable such as USE-2 or URD.

Yes, in standard building installations. XHHW-2 is a single-conductor building wire meant for conduit or other recognized raceways. It can't be run exposed outdoors or fished through walls like NM cable, so inside a wall it has to be in conduit, such as EMT or flexible metal conduit. The NEC allows a few exceptions, such as cable tray for 1/0 AWG and larger conductors with a CT marking, or open wiring on insulators, but these are uncommon.

Yes. NNC's XHHW-2 is marked sunlight resistant, so it holds up in conduit runs exposed to the sun and where the wire leaves the conduit, such as at a weatherhead. Sunlight resistance doesn't replace the conduit requirement.

Yes. XLPE insulation stays flexible in the cold much better than PVC-insulated THHN, which makes XHHW-2 easier to pull in winter. It's commonly rated for installation down to -40°C (-40°F). Check the spec sheet for the exact minimum.

Yes. 4/0 copper XHHW-2 feeds 225A remote power panels and 150 kVA PDUs. Data center loads run continuously, so a 150 kVA PDU at 480V needs 226A of conductor ampacity (125% of 180A), which 4/0 copper's 230A rating covers.