Three products, three jobs
This line groups two automotive families and one industrial one. GPT is general purpose thermoplastic wall primary wire to SAE J1128: a small-AWG bunch-stranded copper conductor in thin PVC insulation, colour coded, running through the body harness of cars and light vehicles. SGT is battery and starter cable to SAE J1127: a heavier bunch-stranded conductor in thicker oil-resistant PVC, commonly red and black in trade channels. Welding cable is the industrial member: an extra-flexible rope-lay copper conductor to ASTM B172 in an EPR rubber jacket to a UL 1581 style construction, rated 600 V and 105 C on the reference rows. The three look similar in a coil but are not interchangeable: GPT walls are too thin and the conductor too stiff for starter current, and welding cable is built for repeated flexing and drag across floors.
Reference rows from public datasheets
Figures below are datasheet rows, quoted as reference values; confirm them on the datasheet of the plant that makes your order. GPT 10 AWG: 19-strand bare copper, PVC wall about 0.81 mm, overall diameter about 4.5 mm, about 57 kg/km and a DC resistance of about 3.55 ohm/km at 25 C. SGT 6 AWG: overall diameter about 7.7 mm on the datasheet row. Welding cable 1/0 AWG, the size most buyers ask about first: overall diameter about 13.9 mm, about 576 kg/km, DC resistance 0.345 ohm/km at 20 C, and an EPR rubber jacket rated 600 V and 105 C, with a low-temperature limit stated per datasheet.
| Product | Standard | Conductor | Jacket | Common sizes | Duty |
|---|---|---|---|---|---|
| GPT | SAE J1128 | Bunch-stranded bare copper | Thin-wall PVC, colour coded | approx. 20-2 AWG in catalogues | Vehicle body circuits |
| SGT | SAE J1127 | Flexible bunch-stranded copper | Thicker PVC, oil resistant | approx. 6-1 AWG in datasheets | Battery and starter circuits |
| Welding cable | UL 1581 style, ASTM B172 | Rope-lay extra-flexible copper | EPR rubber, 600 V, 105 C | 6 AWG to 4/0 AWG | Welder leads and earth leads |
Rated voltage on the automotive types is 60 V DC and 25 V AC, with 80 C and 105 C grades shown on datasheets. Catalogue size ranges differ between sources, so treat the SAE document as the authority for your requirement and the catalogue as a supply indication only.
Standards: SAE, ASTM and UL 1581
SAE J1128 defines GPT and its thin-wall and cross-linked cousins such as TWP, GXL and TXL; SAE J1127 defines SGT. Conductor wire follows ASTM B3 for bunch-stranded conductors; welding cable strands follow ASTM B172, with B174 for the stranded assemblies, and the EPR jacket construction follows the UL 1581 style quoted on the reference rows. For welding installations, NEC Article 630 exists and addresses the conductors supplying the machine; the welding lead itself is selected separately. Rules differ by jurisdiction, so confirm the applicable clause set with your project engineer or the authority having jurisdiction. The desk supplies the construction specified, not a code interpretation.
Welding cable size is the installer's decision
Welder makers publish selection tables that cross the machine's rated current against the one-way length of the lead: longer leads and heavier machines point to larger AWG sizes, and the same table sends one buyer to 4 AWG and another to 2/0. The choice belongs to the installer, who also weighs voltage drop around the full secondary loop, duty cycle and connector fit. The desk ships exactly the size and colour specified and does not choose it for you. Two datasheet facts are worth keeping in view. Strand counts and lay differ between makers even at the same AWG, so overall diameter and flexibility vary and lug and holder fit should be checked against the actual datasheet. And welding cable is made for welder secondary circuits, not for in-line mains voltage wiring, which the datasheets state plainly; the automotive battery cable basics article covers the same confusion on the vehicle side.
What you can change
- Colours: welding cable in black, red or green; GPT in the full solid and stripe colour range for harness work.
- Conductor finish: bare copper as standard; tinned strands on request.
- Print: size, type, standard reference, voltage and footage marks; your brand on private label orders.
- Packing: 100-250 ft reels or coils for welding cable; spools, coils and cartons for small automotive sizes.
Conductor construction and jacket compounds follow the standard or datasheet for each family and should not move to save cost; if a quote looks low, check conductor resistance and wall or jacket thickness first.
MOQ and how the desk quotes
Automotive and welding cable is quoted per size, colour and packing form; welding cable in 100-250 ft reels and coils, and GPT in 100-1000 ft coils, are the common listing formats. MOQ and lead time are confirmed in writing for each order; see MOQ and lead time. Before loading, the desk checks conductor resistance per reel and jacket print against the spec sheet; see testing and inspection. For portable cords in the same enquiry, see the flexible cords line and private label cable for branded packing. Send sizes, colours, reel lengths and port through the quote form.