Wire Price Increases: Romex, THHN and MC Cable Ranked

A wire price increase does not hit every reel on your truck equally, and for an electrical contractor in 2026 the ranking runs like this: MC cable is the most exposed, THHN is next, and Romex is the most damped of the three. The reason is what is wrapped around the copper. MC carries aluminum or steel armor on top of copper conductors, and both of those metals are running harder than copper right now. THHN is close to pure copper with a thin coating. Romex has the heaviest share of plastic in it, and plastic is the calmest input on the list.

One caveat up front, because it matters. No public price index breaks out Romex against THHN against MC. BLS does publish a wire and cable commodity index, copper wire and cable (WPU10260314), and it is the right series to name for wire as a category, but it stops at the category. What follows is a ranking by input exposure, built from what each product is made of and the BLS producer price indexes for those inputs. It is a model of which SKUs should move fastest, not a measurement of which ones did. The measurement has to come from your own invoices, and the last section covers how to get it.

The inputs, and how each one moved in 2026

Four commodity indexes explain almost everything about wire pricing. All are BLS producer price indexes, not seasonally adjusted, with June 2026 readings preliminary.

AGC reports the same categories year over year, and the ordering holds: for the twelve months to May 2026, aluminum mill shapes were up 48.8% and copper and brass mill shapes up 26.8%, against a total nonresidential input index up 8.4%.

Read that table once and the ranking writes itself. Aluminum is the hottest metal in the building. Steel is second. Copper is real but slower. Plastic is nearly asleep by comparison.

On the output side, copper wire and cable (WPU10260314) went 530.917 in January 2026 to 571.299 in June 2026 (P), about +7.6%, and 296.3 in December 2019 to that same June reading, about +93%. That is the blended category, all constructs together, and it is the number to quote when someone asks what wire has done.

The ranking, and the reasoning behind it

1. MC cable: two hot metals in one product

MC (metal clad) is copper conductors inside an interlocking armor, and that armor is aluminum on most of what gets sold, or galvanized steel on the heavier and healthcare-grade products. Whichever it is, you are buying a second metal on top of the copper, and in 2026 both candidates are moving faster than copper.

That is the whole argument. MC is the only common cable where a large fraction of the material cost sits in something other than copper, and where that something is inflating harder than the copper. Aluminum-armored MC has an input running at roughly +58.5% since January 2025. Steel-armored MC has an input at +14.6% in five months.

MC also tends to be bought in the largest reels and the largest single-line dollar amounts, which means a percentage move on MC is a bigger absolute number on your invoice than the same percentage on anything else.

2. THHN: the closest thing to buying copper directly

THHN and THWN-2 single conductors are copper with a thin PVC insulation and a nylon jacket. By share of material cost, this is the most copper-intensive product on the shelf. When copper moves, THHN moves with it, close to one for one, damped only by the manufacturing and distribution layers in between.

The practical consequence is that THHN is your cleanest signal. If you want one SKU to watch weekly as a proxy for what copper is doing to your material budget, make it a stranded THHN size you buy constantly. It tracks the metal more purely than anything else you buy, which also makes it the SKU where an off-schedule jump is most obviously not the market.

3. Romex (NM-B): copper diluted by jacket

NM-B is two or three insulated copper conductors plus a bare ground, a paper or filler separator, and a substantial outer PVC jacket. Compared to THHN, a meaningfully larger share of the material cost is the plastic, and plastics construction products moved 4.1% from January to June 2026 against copper mill shapes at 7.5%.

Romex still rises when copper rises. It just rises less, because part of the product is anchored to a slower input. If your NM-B is climbing at the same rate as your THHN, that is a question worth asking, not a coincidence.

Where aluminum building wire sits

Worth naming separately because contractors reach for it as the copper hedge. In 2026 that hedge is not obviously working. Aluminum mill shapes moved further than copper and brass mill shapes over comparable windows, on both the BLS series and the AGC year over year figures. Aluminum feeder is still cheaper per ampere than copper, but the direction of travel this year is not in its favor, and a bid built on last year’s aluminum spread deserves a fresh look.

The ranking in one table

Sensitivity here means how much of a given copper move should reach the product. Pressure means how hard the product’s total input basket is moving in 2026. They are different questions, and the difference is exactly why MC and aluminum wire can be expensive this year for reasons that have nothing to do with copper.

The pricing mechanics that matter as much as the commodity

Commodity exposure explains the direction. It does not explain your number, because wire is also the category where distributor pricing structure does the most work.

Wire usually has its own category discount. Contractor agreements in electrical distribution are commonly written as category-specific percentage discounts off list, and wire and cable is nearly always its own category with its own rate. One ERP vendor’s worked example lists 25% off wire and cable alongside 20% off lighting and 15% off breakers and panels. Your wire discount can be excellent while your device discount is mediocre, or the reverse, and neither tells you anything about the other. The arithmetic of those rates is covered in column pricing at an electrical distributor.

Special pricing agreements are static and product-specific. Trade press on distributor pricing notes that SPAs are static rather than dynamic, negotiated per product and per customer. So a sharp price on one manufacturer’s 12/2 does not follow you to a different manufacturer’s 12/2 when the counter substitutes. On a forum thread that has been verified against the live page, a contractor makes the same point from the buying side: "One of the things that many contractors don't realize is they need to establish accounts with the supply houses and have them set up SPA prices with the manufactures. This will give you much better pricing." Whether that applies to your reel depends on which brand went in the truck.

Cut wire is not returnable, at most houses. Several published distributor return policies state it outright: no credit on cut wire or made-to-order material, and a second distributor publishes identical terms. Full reels in original packaging can usually come back, subject to a restocking minimum that runs from 15% at those two houses to 25% at others. This is a real reason to buy full reels on volatile SKUs when you can, and the wider version of that calculation is in supply house restocking fees.

Unit of measure is the single most common wire billing error. Wire gets priced per foot, per hundred feet, per thousand feet (per M), and per roll, sometimes on the same invoice. A line priced per M that got entered per hundred is a tenfold error and it does not look like anything until you read the UOM column. Check it before you conclude a price moved at all.

How to build the ranking for your own shop

The general model above is a starting point. Your actual ranking depends on which manufacturers your house stocks, what your category discount is, and how you buy. Twelve months of invoices settles it.

1. Pick one SKU from each family. A 12/2 NM-B 250 ft roll, a 12 AWG stranded THHN in your usual put-up, a 12/2 MC in your usual reel. Note the manufacturer on each.
2. Pull every purchase of those three for twelve months. Date, unit price, unit of measure, branch, quote number.
3. Normalize to price per foot. Different put-ups make raw unit prices non-comparable. This step alone catches UOM errors.
4. Index each to its own starting month. Set month one at 100 for each SKU so you can see relative movement instead of three different dollar scales.
5. Rank the three by total move. That is your real ranking. If it does not match the model above, the difference is telling you something specific about your agreement or your manufacturers.
6. Mark any step that has no matching move in the commodity indexes. Those are the ones to ask about, and they are usually not the market. The same-transaction version of that failure is explained in contract price versus counter price.
7. Watch your THHN weekly and the rest monthly. THHN is the purest copper signal you own. When it steps, expect MC and Romex to follow on their own schedules.

For why those schedules differ, and why the increase always seems to arrive weeks after the copper news, see how copper prices move wire prices at your supply house. For where wire sits against the rest of your material spend, the 2026 trade material cost picture puts all the trades on one page.

The short version

• Ranked by 2026 input pressure: MC cable first, THHN second, Romex third. Aluminum building wire is its own case and is not the safe hedge it was.
• The driver is what is wrapped around the copper. Aluminum armor is riding a 48.8% year over year input. Romex’s PVC jacket is riding a 4.1% five-month input.
• No public index breaks out these three products. WPU10260314 covers wire and cable as a category and no further. The ranking is by exposure; your own price history is the measurement.
• THHN is the cleanest copper proxy you can watch, which makes an off-schedule step on THHN the most legible signal you have.
• Wire is usually its own discount category, SPAs do not survive a brand substitution, and cut wire is generally not returnable at any price.
• Normalize to price per foot before you compare anything. Unit of measure errors on wire are common and large.

Sources

• Aluminum mill shapes (WPU102501), BLS
• No. 1 copper scrap, including wire (WPU10230101), BLS
• Copper and brass mill shapes (WPU102502), BLS
• Copper wire and cable (WPU10260314), BLS
• Steel mill products (WPU1017), BLS
• Plastics construction products (WPU072106), BLS
• Prices for Construction Materials Climb at Highest Rate Since the Pandemic, AGC
• ERP for Electrical Distributors: Catalog Complexity and Contractor Pricing, Bizowie
• Pricing Strategy Starts With Experience, Electrical Trends
• Return Policies, Electrical Wholesalers
• Return Policies, Yale Electric Supply
• Return policy, Colonial Electric Supply
• Are you guys actually getting better pricing with your distributor vs retail, Mike Holt Forums