Weekly digest #154: price changes in copper

Copper jumped again this week. If you bid jobs on materials estimates older than 30 days, you are eating the spread. COMEX copper closed near $5.18/lb on Friday, up roughly 9% over the past three weeks, and distributors have pushed through two price sheet revisions since April 1. Here is what matters on the truck and at the bid table.

What moved and why

Three things stacked on top of each other: a strike at a Chilean smelter cut roughly 180,000 metric tons of refined supply, Chinese grid buildout orders front-loaded Q2 demand, and the AI data center pipeline keeps absorbing every spool of 750 kcmil the mills can roll. None of that is reversing in the next 60 days.

For us, that means THHN, MC cable, and bare copper grounding conductors are all moving on weekly resets, not monthly. Aluminum building wire held flatter, up about 2% in the same window.

• #12 THHN solid: up 11% since March 15
• #6 THHN stranded: up 9%
• 2/0 THHN: up 8%
• #10 bare soft drawn (grounding): up 14%
• 1/2" MC, 12/2 with ground: up 7%

Bid protection that actually works

If your proposals do not have a metals escalation clause right now, add one before Monday. The language does not need to be complicated. Tie it to a published index, set a threshold, and define who eats what above it.

Tip from a Phoenix sub: "We added a 5% threshold tied to COMEX settlement on bid day. First time we used it was a tenant fit-out. Owner pushed back, we showed him the chart, he signed. Saved us $4,200 on one floor."

Also: pull material the day you sign, not the day you start. Storage is cheaper than re-bidding. If the GC will not let you stage on site, most supply houses will hold for 30 days against a PO with a small restock fee waived.

Where aluminum makes sense (and where it does not)

With copper this volatile, aluminum feeders are back in the conversation for runs that were borderline a year ago. NEC 310.16 still governs ampacity, and the upsizing math is the same it has always been: roughly two AWG sizes larger to match copper ampacity, plus terminations rated for the conductor per 110.14(C).

For service entrances 200A and up on long runs, aluminum SER or XHHW-2 in conduit can cut material cost 40 to 55% versus copper at current pricing. Watch your conduit fill per Chapter 9 Table 1 because the larger OD often bumps you up a trade size.

1. Verify lug ratings on the panel and meter base accept AL/CU. Most modern gear does, but resi load centers under 200A are mixed.
2. Use NOALOX or equivalent oxide inhibitor on every aluminum termination. Code does not mandate it for AA-8000 series, but inspectors in several jurisdictions still flag missing inhibitor.
3. Torque to spec with a calibrated wrench. 110.14(D) made this enforceable in the 2017 cycle and inspectors are checking.

Branch circuits inside dwellings stay copper. The labor and termination headache is not worth the savings on #12 and #14 runs.

Theft is up, secure your reels

Three of the larger supply houses in the Southwest reported jobsite copper theft up 60% year over year. Reels left in conex boxes, scrap bins with cutoffs, and partially pulled feeders sitting overnight in unenergized switchgear are all targets right now.

From a foreman in Vegas: "We started cutting our daily pulls so nothing over 50 feet sits overnight. Slower, but we have not lost a reel since February. Math works out."

If you are running a long-duration project, check whether your GL policy actually covers theft of materials you have already taken delivery on but not installed. A lot of policies have a sub-limit that will surprise you.

Estimating adjustments for the next 30 days

Until the market settles, build your estimates with these assumptions and document them on the proposal so the customer sees the logic.

• Use distributor quotes dated within 7 days, not 30
• Add a 4 to 6% materials contingency line item, separate from your overhead and profit
• Quote validity: 14 days, not 30
• For projects starting more than 60 days out, escalation clause is mandatory, not optional
• Spec aluminum as an alternate on any feeder run over 100 feet at 100A or larger

If you are on a long T and M job, talk to your customer this week about a materials review. Most reasonable owners would rather see a transparent adjustment now than a fight at closeout.

Code reminders that come up on copper jobs

A few articles worth re-reading when you are switching between copper and aluminum on the same project, or when you are tempted to downsize because of cost pressure.

• NEC 110.14(C): termination temperature ratings. The conductor ampacity is limited by the lowest-rated component in the circuit, including the lug.
• NEC 210.19(A) and 215.2(A): minimum branch circuit and feeder conductor sizing. Voltage drop is a recommendation in 210.19 informational note, not a requirement, but losing it on a long run will cost you a callback.
• NEC 250.122: equipment grounding conductor sizing per Table 250.122. If you upsize your phase conductors for voltage drop, you proportionally upsize the EGC per 250.122(B).
• NEC 300.3(B): all conductors of the same circuit in the same raceway. Splitting copper neutrals from aluminum phases across separate conduits is a violation people try to get cute with.

Stay sharp on the bid table this week. The guys who lose money on copper runs in 2026 are going to be the ones still using last quarter's price sheet.