UL 1591 FEP Hook-Up Wire 26 AWG — One Wall Figure Across the Style, 150°C at 300 Vac
UL 1591 in 26 AWG is a single-conductor appliance wiring material with extruded FEP insulation, rated 150°C maximum at 300 Vac with a horizontal flame rating. The style specifies a single insulation figure for its entire 32 AWG to 16 AWG range — 16 mils minimum average thickness, 13 mils minimum at any point — rather than a bracket table that steps with conductor size. For a harness that mixes several gauges from this style, that single figure removes a class of specification work that bracket-scaled styles impose. CableApex supplies UL 1591 26 AWG as a UL Recognized Component — file on record.
What a Single Wall Figure Removes from the Design Process
In a style with wall brackets, changing a conductor gauge can change the insulation dimension as well — and whether it does depends on which side of a bracket boundary the new gauge falls. That introduces a check that has to be repeated every time a circuit is resized: look up the new gauge, find its bracket, confirm the wall, recalculate the finished outside diameter, then verify that grommets, bushings, harness fill and crimp barrels still work with the new figure. When several circuits in one harness are revised, the check multiplies.
UL 1591 does not have that structure. A 32 AWG lead and a 16 AWG lead carry the same 16 mils nominal wall, and so does every gauge between them. The finished outside diameter therefore varies only by the conductor diameter, which is a figure the designer already knows from the AWG. Resizing a circuit from 28 AWG to 26 AWG changes the diameter by the conductor difference alone, and the insulation dimension used in every downstream calculation stays put.
Selection Effects of the Uniform Wall
| Design activity | Bracket-scaled style | UL 1591 uniform wall |
|---|---|---|
| Changing a circuit gauge | Check whether a bracket boundary was crossed | Wall unchanged; diameter shifts by conductor only |
| Mixed-gauge bundle diameter | Wall varies by gauge group | One wall figure applies to all members |
| Grommet and bushing sizing | Recheck after any gauge revision | Stable unless the conductor itself changes |
| Strip and crimp tooling setup | Insulation dimension differs across gauge groups | Consistent strip depth across the style |
UL 1591 26 AWG Specifications
| Item | Specification |
|---|---|
| UL Style | 1591 — single conductor with extruded insulation |
| Temperature Rating | 150°C maximum |
| Voltage Rating | 300 Vac |
| Conductor | 26 AWG, solid or stranded (style range 32–16 AWG) |
| Conductor Plating | Silver plated, nickel coated copper, nickel plated, or tin plated |
| Insulation | Extruded FEP, 16 mils minimum average thickness, 13 mils minimum at any point — uniform across the full range |
| Flame Rating | Horizontal flame; VW-1 vertical flame test available |
| UL Recognition | UL Recognized Component — file on record |
| Marking | Per UL Subject 758 marking requirements |
| Permitted Use | Internal wiring of appliances |
| RoHS / REACH | Documentation available on request |
Plating Remains Available at Every Gauge
The same absence of size-dependent conditions applies to the conductor. UL 1591 recognises silver plated, nickel coated copper, nickel plated and tin plated conductor across the whole 32 to 16 AWG range, with no gauge restriction on any of them. That is a meaningful difference from UL 1592, where tinned copper is confined to 26 AWG through 16 AWG and additionally carries a 15 mils minimum strand diameter condition. A design that specifies tin plated conductor at 26 AWG and later revises the circuit to 28 AWG stays within UL 1591 without a conductor change; the same revision under UL 1592 would fall outside the tinned copper window.
Applications
Within its permitted use — internal wiring of appliances — UL 1591 26 AWG suits fine signal and sensor leads, low-current control conductors and internal interface wiring in appliances operating at 300 Vac in zones reaching 150°C. It is well suited to harnesses that carry several gauges from the same style, where the uniform wall keeps bundle geometry and tooling setup consistent across the members. Specify the conductor plating according to the termination method and the sustained operating temperature the lead will see. For applications outside internal appliance wiring, confirm application suitability before specifying.
Key Features
- One 16 mils wall figure across the full 32–16 AWG range
- Gauge revisions change diameter by the conductor only
- Consistent strip depth and bundle geometry across mixed-gauge harnesses
- All four plating options available at every gauge without restriction
- Horizontal flame; VW-1 vertical flame test available
- UL Recognized Component — file on record
Request a Quote
CableApex supplies UL 1591 26 AWG from 100 m per color and responds to B2B inquiries within 12 hours. Specify conductor construction (solid or stranded), the required plating and colors through the form below. If the harness uses several gauges from this style, list them together so they can be quoted and packed as a set.
Related pages: UL 1591 24 AWG · UL 1592 FEP Wire (200°C / 300 Vac) · UL 1591 FEP Wire category
