Southwire From a Procurement Desk: A TCO-Focused Overview, Type W Cable, and the 1507 Insulation Tester

The Fast Answer: Evaluate Southwire on Total Cost, Not Unit Price

Southwire is not the cheapest wire and cable brand on every SKU, and honestly, neither should you be buying the cheapest. I have managed a $900,000 annual electrical materials budget for a 34-person electrical contracting company for the last eight years. When I compare supplier quotes, I track more than the line item price. If your procurement process only compares per-foot cost, you will miss the two places Southwire pays for itself: documentation and consistency.

Bottom line: In my TCO spreadsheet, Southwire's total installed cost is usually lower than the cheap quote—even when the invoice is higher. That is not a marketing take; it is what the numbers say after counting rework and time.

I did not always think this way. In Q2 2023, we bought a cheaper type W equivalent cord for a temporary feeder. We saved $308 on the order. It cost us about $1,100 in labor when the jacket split and the customer called us back. Since then, every cable vendor quote gets a total-cost review.

Southwire Company Overview for Buyers

According to Southwire's corporate overview page (southwire.com, accessed February 2025), the company was founded in 1950 and is headquartered in Carrollton, Georgia. It is one of the largest privately held wire and cable manufacturers in North America. For procurement, that means one thing: supply chain scale. Southwire's product line covers building wire (THHN, NM-B, MC), portable cord and power cable like Type W, utility cable, and a line of testing tools and accessories.

Southwire Technology Ventures is the company's investment arm, focusing on electrification, grid modernization, and the kind of infrastructure shifts that affect product availability. I do not evaluate vendors by their press releases, but this matters to me because it signals they are not planning to ride out the market with obsolete SKUs.

You will also see Infinity on some Southwire communication and low-voltage cabling products. If you ask for Southwire Infinity, make sure you are looking at the right product family—it is not a substitute for Type W or THHN without checking the data sheet. That is a purchasing mistake easy to make when a distributor's search bar returns one brand with lots of SKUs.

What Actually Moves the Cost of Cable

The assumption in a lot of bid reviews is that a higher quote means you are paying for a brand name. In practice, cable price differences come from material specs: copper strand count, jacket thickness, insulation rating, and manufacturing quality control. Type W cable is a perfect example. Per UL 1585, Type W is a 600 V portable power cable for tough service. The copper alone changes the price before you add a heavy-duty thermoset jacket that can survive water, sunlight, and dragging over edges. That is not branding. That is material.

There is also a bad assumption that buying better cable always costs more. Actually, the opposite can be true on the job site. A cable that is easier to pull, has a clean spec sheet, and arrives with the right markings saves labor. Labor is usually the biggest line item on any job. Paying $0.20 more per foot on 500 ft is $100. Swapping out a damaged feeder costs hours, plus the frustration of explaining to a customer why power went down.

Here is a realistic comparison from a quote I received in January 2025: 250 ft of an off-brand type W style cord came in around $0.87 per foot. The comparable Southwire Type W quote was roughly $1.02 per foot. Difference: $37.50 total. On that same project, a two-hour electrical call-out was around $500 before materials. One rejected inspection, one wet jacket, or one trip back to the supply house wipes out the savings. That is the calculation I keep coming back to.

Southwire Type W Cable: When I Buy It

The Southwire Type W cable that shows up on our job sites is the portable power cable we use for temporary power, generators, distribution panels, and any feeder that gets dragged around. It is rated 600 V and built with stranded copper conductors. The jacket is where it earns the price. Type W is not a replacement for THHN inside conduit, and if you need maximum flexibility for hand tools, SOOW is often more appropriate. But for a feeder that will be pulled by a worker and then driven over by a forklift, Type W is the right class.

On a cost comparison, Type W will always be beaten by a lighter cord. That is fine. I have rejected type W equivalent claims more than once because the datasheet did not list the same jacket material or strand count. If the material spec is close enough, we talk. If not, the cheap quote is not cheap; it is a risk line item.

How to Use the Southwire 1507 Insulation Tester

The Southwire 1507 (sold as the 1507T on some labels) is a handheld insulation resistance tester. It gives you a DC test voltage and measures insulation resistance in megohms. If you reuse cable or want proof that a feeder was not damaged before you pull it, this is the tool. Here are the steps we use on a de-energized cable:

1. Lock out and tag out the entire circuit. Disconnect the cable at both ends. Confirm no voltage with a voltmeter phase-to-phase, phase-to-ground, and neutral-to-ground before connecting the tester.
2. Select the test voltage. For a 480/277 V feed, I use 500 V. For 600 V portable cable, I use 1000 V. Check your manual and your customer's spec before choosing.
3. Connect the red lead to the conductor under test and black to the ground conductor. Keep the other conductors grounded while you test one conductor at a time.
4. Press and hold the test button. Let the reading settle for at least 60 seconds if the cable is long or wet. The reading should climb and then stabilize. A steady drop means moisture or damage.
5. Record the 60-second value and compare it to previous readings or manufacturer acceptance values. If it is below 1 MΩ, I do not put it into service without a written engineering sign-off.
6. After testing, release the button and let the cable discharge before disconnecting the leads. The 1507 does this internally, but I still wait a few seconds.

The first time I used one was after a sub told us the used feeder cable he was selling was basically new. The 1507 showed 0.2 MΩ after rain. His price was 40% below new Type W. The tester cost less than the overtime to install and rip it out would have cost.

Where This Does Not Apply

Not every Southwire purchase makes sense. If a project is long-term installed building wire and does not need field-tool support or heavy abuse, a commodity THHN quote from a local distributor is fine as long as it meets spec. And if your vendor gives you a certified Type W datasheet with the same construction, save the money. I do not care about the logo. I care about predictable total cost.

The reason I keep coming back to Southwire is that their documentation and tools lower our risk. That includes the voltage drop calculator on their website, the spec sheets, and even the 1507 operating guide. Those are not extras; they are cost-saving tools. Verify current prices and specs before you buy—my data is from February 2025 and electrical material prices move.