Picking the right wire type seems simple — until you're standing at the supply counter with a contractor invoice in one hand, an inspector's red tag in the other, and a project deadline closing in. THHN, XHHW, and MC cable all carry power, all sit in conduit (or in the case of MC, are pre-armored), and all are stocked at most distributors. But they price differently, install differently, and pass inspection in very different scopes. Here's how Tech Energy America walks contractors through the choice.
Quick reference cheat sheet
| Type | Insulation | Wet rated | Conduit? | Common use |
|---|---|---|---|---|
| THHN | PVC + nylon | THWN-2 dual rated | Required | Branch circuits, feeders inside conduit |
| XHHW | Cross-linked polyethylene | Yes (XHHW-2) | Required | Service entrance, feeders, wet/damp |
| MC | THHN cores + aluminum armor | No (interior only) | Pre-armored, no conduit | Commercial branch circuits, hospital |
THHN — the workhorse
THHN (Thermoplastic High Heat-resistant Nylon-coated) is by far the most popular building wire in the United States. The PVC core insulation rated at 90°C dry combined with a thin nylon outer jacket gives it excellent abrasion resistance and a slick surface that pulls easily through long conduit runs. Almost every THHN you'll buy from Tech Energy America is dual-rated as THWN-2, meaning it's also rated for wet locations at 90°C — making it suitable for almost all branch circuits and feeders pulled inside EMT, RMC, IMC, or PVC conduit.
Where THHN shines: residential service upgrades, commercial branch circuits in EMT, panelboard wiring, motor leads, and any location where you're already running conduit. Sizing follows NEC Table 310.16 — the 90°C column for design, the 75°C column for OCPD termination temperature limits.
XHHW — the cross-linked specialist
XHHW (Cross-linked polyethylene High Heat-resistant Water-resistant) replaces the PVC insulation with cross-linked polyethylene. The result: better thermal performance, better resistance to chemicals and ozone, and noticeably lower smoke and toxicity in a fire. Modern XHHW-2 is rated 90°C in both wet and dry locations, identical to THWN-2 on paper. So why pay the premium?
Three reasons: (1) service entrance and feeder conductors on commercial and industrial projects often spec XHHW-2 by default for the lower smoke/toxicity benefit; (2) it has better long-term aging at high temperatures, which matters for switchgear lugs that run hot under load; (3) some specifications — particularly hospital, data center, and federal projects — require it. If you're pulling 4/0 or larger feeders into a 1200A switchboard, XHHW-2 is usually the right call.
Distribution partners like Priority Wire, Southwire, and CME Wire stock both THHN and XHHW in matching sizes. Lead time and stock availability often decide the tie when both are spec'd.
MC cable — when conduit isn't worth the time
Metal Clad cable bundles 2–4 THHN-style conductors plus a ground inside an interlocked aluminum armor jacket. You don't need conduit — MC can be run exposed, in stud bays, in cable trays, or above accessible ceilings, dramatically reducing labor cost on commercial projects with hundreds of branch circuits.
The trade-off: MC cable is approximately 1.5× to 2× the per-foot cost of bare THHN, but you save roughly 30–50% on installation labor by skipping the conduit run. On a 100,000 sq ft commercial buildout with 200+ branch circuits, the math usually favors MC for circuit-side wiring (the feeders still go in conduit).
Hospital MC, healthcare MC, and HCF cables are specialty MCs with redundant grounding for patient-care areas — required by NEC 517 in operating rooms and patient rooms. Tech Energy America stocks the standard MC; healthcare-rated cable usually has a 1–2 week lead time depending on quantity.
How we recommend choosing on your next project
- Conduit pre-determined? THHN/THWN-2 in 99% of cases. Cheapest, easiest, most flexible.
- Wet/damp + commercial spec? XHHW-2 is the safer call for service entrance, feeders, parking decks, and exterior runs.
- Lots of branch circuits + accessible ceiling? MC for circuits, conduit for feeders. Faster install, lower total job cost.
- Hospital / healthcare? MC-HCF and XHHW-2 mandated by NEC 517 — don't substitute.
- Solar PV? Not in this article — that's USE-2 / PV wire, governed by NEC 690. We'll cover it next.
Pricing snapshot — Arizona, May 2026
For a 12 AWG copper, 1000 ft reel:
- THHN/THWN-2 (Priority): ~$165–$190
- XHHW-2 (Southwire): ~$210–$240
- MC 12-2 w/G (Southwire SimPull): ~$295–$340
Larger sizes scale linearly with copper commodity pricing. Tech Energy America locks pricing on contractor-account quotes for 14 days from issue. Request a wire & cable quote with your bill of materials and we turn it around in 24–48 hours.
Common mistakes we see
- Using THHN in wet locations without verifying THWN-2 dual rating. Most modern stock is dual-rated, but old inventory might not be — check the print legend.
- Sizing on the 90°C column when the breaker terminations are 75°C only. NEC 110.14(C) limits ampacity to the lowest-rated termination. Most breakers below 100A are 60°C/75°C — design accordingly.
- Running MC where the AHJ requires conduit. Hazardous locations, plenum spaces with restrictions, and certain industrial occupancies don't allow MC. Check your jurisdiction.
Related reading
- More articles on the Tech Energy America blog
- Wire & cable products we distribute
- Electrical contracting services in Arizona
Need a wire and cable quote?
Tech Energy America is an authorized distributor of Priority Wire, Southwire, CME, and Kris-Tech. We respond to RFQs in 24–48 hours.
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