Match the tag to the wire before reading the numbers
A label attached to a reel describes its original contents. It does not prove that the wire now wound on it matches. Rewound cable, loose tags and handwritten labels need a second check.
- Photograph the whole reel so its tag, wire color and condition appear together.
- Read the factory tag, including small print and any separate listing label.
- Find one complete repeat of the print on the insulation or outer jacket.
- Compare the type, size, metal and manufacturer. If they disagree, record the mismatch rather than choosing whichever label is clearer.
Do not unroll a heavy reel just to find a marking. Inspect accessible wire on material that is disconnected and secured against movement. For other inventory questions, use the wire selling guides.
Read these fields on the reel tag
Tag layouts vary. This chart gives you a reading order, not a universal manufacturer format.
| Field | What to record | Mistake to avoid |
|---|---|---|
| Manufacturer | Full name or identifiable brand | Confusing the distributor with the maker |
| Product or stock number | Every digit and suffix | Treating a barcode number as conductor size |
| Type | THHN/THWN-2, XHHW-2, MV-105 or the complete marked designation | Dropping a suffix that changes the rating |
| Size | AWG, slash-zero size or kcmil, exactly as shown | Writing only a number without its unit |
| Conductor material | Copper, aluminum or a specifically named clad material | Guessing from jacket color |
| Construction | Solid, stranded, compact, conductor count, pairs or shield details | Confusing strand count with conductor count |
| Voltage and temperature | Each rating with its associated type | Treating voltage as an ampacity |
| Length | Factory footage and separately documented remaining footage | Calling an opened reel full |
| Reel, lot and date codes | Each code under its own label | Assuming every number is a date |
| Listing label | Entire label and identifying numbers | Photographing only the logo |
Keep factory information separate from your inventory notes. A handwritten remaining length can help, but identify who measured it and how.
Decode a building-wire print line
Here is a shortened teaching example, not a complete factory legend: MAKER 4/0 AWG CU TYPE THHN/THWN-2 600 V. Actual legends may contain additional ratings, file numbers, test markings and dates.
| Portion | Meaning | Why it matters |
|---|---|---|
| MAKER | Manufacturer identification | Helps locate the correct specification |
| 4/0 AWG | Conductor size | Preserve the slash and zero |
| CU | Copper conductor | Distinguishes it from aluminum |
| THHN/THWN-2 | Two marked wire types | Do not shorten the record to THHN alone |
| 600 V | Voltage rating | Not a statement of allowable current |
THHN identifies thermoplastic insulation with a nylon covering and a 90°C dry-location rating. THWN-2 adds the wet-location rating of 90°C. Southwire’s cited copper specification supports those ratings and describes PVC insulation beneath a nylon sheath.
A print line on single-conductor building wire is not necessarily on a separate cable jacket. On multiconductor cable, the outer jacket and individual conductor insulation may carry different information. Photograph both when accessible without cutting. The THHN and THWN-2 page covers that wire family.
Keep size, metal and construction separate
1 AWG and 1/0 AWG are different sizes. Slash-zero sizes progress through 1/0, 2/0, 3/0 and 4/0. Read the zero carefully in a faded print. The 1/0 through 4/0 size guide groups those sizes separately.
For larger conductors, kcmil and MCM refer to the same size unit, thousands of circular mils. Neither is a footage measurement. Keep a marking such as 500 kcmil intact when listing 250 through 500 kcmil conductors.
AL identifies aluminum. CU identifies copper when marked. Copper-clad aluminum is a separate construction, not solid copper. UL’s guide lists several permitted ways to mark clad material, so copy the full wording.
Conductor count and strand count answer different questions. A single conductor can contain many small strands. On multiconductor cable, record any equipment grounding conductor separately if the product description does so. Do not assume a notation such as 12/3 tells you every component inside without checking the cable type and specification.
Read rating codes without assuming interchangeability
UL’s guide explains that products with multiple type designations have been evaluated for those marked types. That does not make two similar-looking cables interchangeable.
| Marking | What it tells you | What it does not tell you |
|---|---|---|
| SUN RES or SUNLIGHT RESISTANT | Sunlight-resistance evaluation | That stored cable has no damage |
| FOR CT USE | Cable-tray-use evaluation | That all installation methods are permitted |
| DIRECT BURIAL | Direct-burial evaluation | That every black cable has this rating |
| AWM | Appliance wiring material designation | Permission for general field installation by itself |
| UL surface symbol or letters | Supplemental product marking | Complete listing evidence without the package label |
Preserve the original reel or package listing label. UL identifies that complete label, rather than surface lettering alone, as the evidence of its listing coverage.
A second teaching example is 500 KCMIL CU NL-EPR 15KV 133% INS LEVEL MV-105. It describes conductor size, copper, an ethylene propylene rubber insulation construction, voltage class, insulation level and type. The 133% is an insulation-level designation, not remaining footage or conductor size. MV-105 identifies a 105°C conductor temperature rating; it does not mean 105 kV. Keep shield details and insulation level when identifying medium-voltage cable.
Calculate footage only after checking the marking system
A factory tag reading 2,500 feet is not evidence that 2,500 feet remains. Some print numbers are production counters, not reel-relative footage.
For a hypothetical continuous length with verified foot markings of 1,840 at one end and 1,120 at the other, subtract the smaller reading from the larger: 1,840 minus 1,120 equals 720 feet. This works only when both readings belong to that continuous length and the sequence has not reset.
Cerrowire’s True Sequential Footage system is different from a generic production counter. On its applicable original Master Reels, markings begin at zero at the bottom and end at the finished length on the outer end. Check that the reel uses that system and has not been rewound before treating an outer reading as remaining length.
If the inner end is inaccessible, report the visible number without claiming a confirmed length. Use the reel footage guide for another measurement method, and label estimates as estimates.
Preserve identification on Arizona project leftovers
Arizona solar and battery work makes accurate product sorting important. SRP’s October 2024 announcement described completion of the Eleven Mile Solar System near Coolidge in Pinal County. A solar project label alone does not identify every reel as PV wire. Keep PV wire identification separate from feeder and collection-cable descriptions.
For outdoor-stored reels, photograph faded tags, cracked coverings, damaged flanges and exposed ends. A sunlight-resistance marking does not erase visible deterioration. Record storage exposure as well as the manufacture code; a clear tag cannot establish condition. For MV cable, show whether both ends are sealed without removing the seals. Storage exposure, jacket condition, reel condition and sealed ends on MV cable affect the offer. The Arizona heat and sun storage guide addresses those storage concerns.
Build a photo set that answers identification questions
Before sending your inventory, check that you have:
- One overview showing each reel and its own tag together.
- A sharp close-up of the complete tag and separate listing label.
- Enough overlapping print photos to capture every character in one repeat.
- Footage markings with their units and your measurement method.
- Accessible end and condition photos, without removing intact insulation or seals.
- An inventory row for each reel, including unknown or conflicting details.
List faded-tag reels separately until the jacket print or purchase records establish their identity. Do not combine their footage with a matching-looking reel based only on color.
We buy all types of electrical wire and cable, new, unused, leftover or used. Full reels, partial reels, boxed coils, cut lengths and mixed lots are welcome. To request a written offer, send this photo set and your Arizona location. We pick up anywhere in Arizona.