I need to know the difference if any between AWG ratings on extension cords vs. USW vs. AWG SJTW vs. SJTW. Are these standards all the same? At best, Google says USW is for the steel workers. But I an unclear how that relates. Thanks all!
You’re mixing up at least two things here: wire and insulation. The thickness of the wire is noted in AWG, with a larger number for thinner wire. Wires are often grouped into bundles called cables. The insulation on the wires designates use, type, chemical resistance, and insulation. SJTW is SJTW stands for Hard service cord, thermoplastic constructed jacket, 300 volt, weather resistant for outdoor use. S = service, J = Junior, T = Thermoplastic/Vinyl, W-A = Weather Approved.
USW is the manufacturer, US Wire and Cable http://www.uswireandcable.com/glossary.html.
USW is also the steelworkers union.
Jinx, this is one of those cases where it would be really helpful if you asked the question you want the answer to. As stated, there’s no answer to your OP, so the best you’re going to get is random guesses as people make assumptions based on the little bit of information you gave.
What are you trying to figure out? As noted by Fins, AWG, SJTW and USW don’t related to each other in any way.
IOW, what is the exact wording of whatever it is you’re trying to find an answer for.
ETA, I presume you have something that gave you some type of requirements for adding a cord to it. What do the instructions say?
AWG indicates the thickness of the cable however with modern cables often containing thinner strands of copper or possibly aluminium their likely to be physically a different size than the indicated AWG. It might still be marked in AWG which is fine till your wondering why your cable and cable lug are a mismatch.
This is not correct. AWG describes the actual metal conductor size (including the diameter). Wires of identical gauge are identical in diameter. Now, the actual exterior physical dimensions of the cable or of individual insulated conductors (like THHN or XHHW) may vary due to their construction. See Table 8 in Chapter 9 of the NEC for further information.
Not sure why you refer to diameter there. AWG describes the cross sectional area of a wire. Diameter for stranded is not a precise measurement because the cross section isn’t circular and varies in shape with the number of strands.
ETA: Noting the cross section area is the conductor area, stranded wires have air space in the cross section.
As I said in my post, it’s wire not cable. Wire is 1, cable is more than 1 usually with an additional outer covering.
To expand on this…
Electrical wires have a metal conductor (usually copper), and the wire is usually insulated. Some wires have a single conductor, while others have multiple conductors. We call the latter “stranded wires.”
The AWG refers to the total cross-sectional area of the conductor only; it does not include the insulation. For wires containing a single, solid, round conductor (“single strand”), the area is πr². For stranded wires, the total cross-sectional area is simply the area of each strand added together.
The following equation gives you the total cross-sectional area of the conductor for a given AWG:
A = PI()(0.063592^((36-n)/39))^2
where
n is the AWG number
A is the total cross-sectional area of the conductor (mm[sup]2[/sup])
As an example, a 12 AWG wire has a conductor with a cross-sectional area of 3.3088 mm[sup]2[/sup].
Now, the above equation is pretty exact when it comes to single strand wires. Ideally it would also be true for stranded wires, but that’s not the case.
Here is a company that sells wire. Below are the cross-sectional areas for the 8 AWG wires they sell. To calculate total cross-sectional area I used the equation above to calculate the cross-sectional area of each strand and then multiplied by the number of strands. Note that the first one is a single strand, and is thus “ideal” according to the equation.
Stranded 8 AWG Wire
No AWG of Area of Total
of Each Each Area
Strands Strand Strand (mm[sup]2[/sup])
(mm[sup]2[/sup])
-------- -------- -------- --------
1 8 8.366 8.366
7 16 1.309 9.161
19 21 0.410 7.799
37 24 0.205 7.575
49 25 0.162 7.956
133 29 0.064 8.541
152 30 0.051 7.741
168 30 0.051 8.556
245 32 0.032 7.847
301 33 0.025 7.645
413 34 0.020 8.319
602 36 0.013 7.626
665 35 0.016 10.622
1050 38 0.008 8.365
For their 8 AWG stranded wires, 1050 strands of 38 AWG wire comes “closest” to the ideal, whereas 665 strands of 35 AWG wire deviates the farthest from the ideal.
Technically, you are correct. But NEC describes conductors by both diameter and cross-sectional area, with separate entries for solid (1 strand) and stranded (7 strands) conductors.
Sorry for the confusion. I need a 100-ft, 12 AWG extension cord. Simple enough, but when I look at Home Depot’s website, the descriptions are inconsistent. Not all give AWG, but they give other alphabet soup markings that can only lead me to wonder if it is an equivalent to AWG. Hence, my confusion. I am surprised AWG is not in all the descriptions for extension cords.
Don’t over think it.
https://www.homedepot.com/p/RIDGID-100-ft-12-3-Outdoor-Extension-Cord-657-123100RL6A/302877751
That’s a 12AWG 100ft extension cord. When you look at extension cords, there’s two numbers. This one is 12/3. It’s AWG/number of conductors (hot/neutral/ground, in this case). As long as you get one where the first number is 12 or lower, you’re meeting the requirements.
Something to keep in mind: if the tool or appliance pulls a lot of current, e.g. 13 A, that extension cord will reduce the voltage by 4 V. So if there’s 120 VAC at the outlet, the tool/appliance will get 116 VAC. This is not a problem for most things, but it’s just something you should be aware of. It can also cause problems with things that require a high level of inrush current at power-up.