UL 1538 Back Panel Wire Overview
UL AWM Style 1538 is a single-conductor fluoropolymer insulated wire construction, supplied by CableApex as a factory-direct manufacturer, specifically defined for use in back panel areas of electronic equipment such as electronic computers and business machines, where the wire is not subjected to movement or mechanical damage. The wire is rated 105°C and 125 Vac, with a conductor range of 36 AWG through 6 AWG, solid or stranded, insulated with extruded FEP, PFA, or PTFE. This page focuses specifically on the UL 1538 back-panel application intent; buyers with a general high-temperature fluoropolymer wire need outside this specific use should confirm whether a different Style, such as UL 1332, UL 1659, or UL 10362, better fits their application.
105°C / 125 Vac Electronic Equipment Wiring
| Parameter | UL Style 1538 |
|---|---|
| UL Subject / Section | 758, Section 1 |
| Construction | Single conductor with extruded insulation |
| Rated Temperature (Maximum) | 105°C |
| Voltage Rating | 125 Vac |
| Flame Rating | Horizontal flame |
| Conductor Size Range | 36 AWG – 6 AWG |
| Conductor Construction | Solid or stranded |
| Insulation | Extruded FEP, PFA, or PTFE |
| Optional Conditions | 60°C or 80°C Oil; Gasoline Resistant, where qualified |
| Marking | General; tags may optionally indicate “300 peak volts for Electronic use only” |
| Use | Back panel areas of electronic equipment, such as electronic computers and business machines, where not subjected to movement or mechanical damage |
| RoHS / REACH | Confirmed during quotation according to ordered materials and documentation requirements |
The 105°C / 125 Vac rating applies to the complete Style 1538 construction. This page does not describe the product as a high-temperature fluoropolymer wire in the sense of 200°C or 250°C Styles — the broader temperature capability sometimes associated with fluoropolymer materials in general does not raise the finished Style 1538 rating above 105°C. Certain qualified Style 1538 constructions may carry a tag indicating “300 peak volts for Electronic use only” — this is a distinct marking provision, not a 300 Vac continuous operating rating, and the primary product rating remains 125 Vac.
FEP, PFA or PTFE Insulation Options
UL Style 1538 permits extruded FEP, PFA, or PTFE as the insulation material. These are not treated as interchangeable materials with identical properties on this page — each is a distinct fluoropolymer chemistry, and the specific material used in a given order should be specified during quotation. Regardless of which qualified insulation material is selected, the finished Style 1538 construction remains rated 105°C and 125 Vac; selecting PTFE, for example, does not convert the product into a UL 1659 (250°C / 600 Vac) construction, and selecting PFA does not convert it into a UL 10362 (250°C / 600 Vac) construction. Style identity is determined by the qualified UL construction as a whole, not by insulation material alone.
36–6 AWG Solid or Stranded Construction
UL Style 1538 covers a conductor range of 36 AWG through 6 AWG, solid or stranded. We do not publish strand count, strand diameter, conductor lay, conductor resistance, or ampacity on this page, as none of these are established by the Style-level record. Conductor material and finish are also not established at the Style level and should be specified when requesting a quotation. Not every AWG within the Style range is necessarily in continuous stock — available sizes are confirmed at the time of quotation.
UL 1538 Insulation Wall Requirements
| Conductor Size | Min. Average Thickness | Min. Thickness at Any Point |
|---|---|---|
| 36–20 AWG | 5.5 mils | 5 mils |
| 19–15 AWG | 8 mils | 7 mils |
| 14–10 AWG | 13 mils | 12 mils |
| 9–6 AWG | 20 mils | 18 mils |
We do not calculate or publish a finished outside diameter from AWG and insulation thickness, as conductor diameter and manufacturing tolerances are not part of the confirmed technical basis for this page. If dimension is critical to your design, please provide your required finished OD or available routing space with your enquiry.
Back Panel Areas of Electronic Equipment
UL Style 1538 is designated for use in back panel areas of electronic equipment, such as electronic computers and business machines. Appropriate application language for this page includes electronic equipment back panel wiring, protected back panel internal wiring, static internal electrical connections, and internal wiring in protected back-panel areas. This page does not broaden the use into general machinery wiring, industrial control wiring, field wiring, building wiring, robotics wiring, moving equipment wiring, cable carriers, or drag chains, and does not extend the “electronic computers and business machines” examples into unsupported sectors such as data centers, telecommunications infrastructure, medical electronics, aerospace electronics, or automotive electronics.
Static Protected Wiring — No Movement or Mechanical Damage
This is one of the most important restrictions on this page. The UL use statement explicitly limits Style 1538 to areas not subjected to movement or mechanical damage. This page does not describe UL 1538 as a flexible cable, high-flex wire, continuous-flex wire, moving cable, robotic cable, drag-chain cable, or abrasion-resistant moving wire, and does not publish a bend radius or flex-cycle rating. The Style is specifically suited to protected, static back-panel routing within the electronic equipment housing.
UL 1538 vs General Fluoropolymer AWM Wire
UL 1538 is a distinct, application-specific UL Style rather than a general-purpose high-temperature fluoropolymer wire. Other CableApex fluoropolymer AWM Styles serve different needs: UL 1332 is a 200°C / 300 Vac FEP construction for broader appliance internal wiring; UL 1659 is a 250°C / 600 Vac PTFE/TFE construction for internal wiring; UL 10362 is a 250°C / 600 Vac PFA construction for internal wiring. UL 1538, by contrast, is defined specifically around its 105°C / 125 Vac rating and its back-panel-of-electronic-equipment use boundary, with the restriction that it not be subjected to movement or mechanical damage. Selecting UL 1538 with a PTFE or PFA insulation does not make it equivalent to UL 1659 or UL 10362 — the complete qualified Style construction, not the insulation material alone, determines which Style applies.
What to Specify When Ordering UL 1538 Wire
To provide an accurate quotation for UL 1538 back panel wire, please specify:
- Required AWG within the 36–6 AWG range
- Solid or stranded conductor
- Required conductor material or finish
- Preferred insulation: FEP, PFA, or PTFE
- Required operating voltage
- Required operating temperature
- Oil or gasoline-resistance requirement, if applicable
- Required finished OD, if dimensionally constrained
- Insulation colour
- Order quantity
- Packaging requirement
- UL marking requirement, if applicable
- Documentation requirements, including RoHS / REACH if needed
- Electronic equipment type
- Back-panel routing condition
- Shipping destination
Send this information and we respond with a quotation within 12 business hours. Production lead time depends on the confirmed construction and order quantity, and shipping options and applicable Incoterms are confirmed during quotation according to destination.
UL Marking and Documentation
Qualifying UL AWM Style 1538 constructions can be supplied through the relevant qualified manufacturing scope for this Style. UL marking and documentation must correspond to the confirmed qualified Style 1538 construction supplied for the order and are not identical across every commercial variation. RoHS and REACH are separate regulatory frameworks from UL recognition; applicable RoHS / REACH documentation requirements can be confirmed according to the ordered construction.
Browse our full Special Application Cable category, or see our general Fluoropolymer Wire range — note that the broader fluoropolymer category covers multiple Styles, while this page specifically addresses the UL 1538 back-panel construction.
