UL 5128 450°C 300V Mica Wire with Optional SS304 Braid
UL AWM Style 5128 is a single or multiple conductor with other-than-extruded insulation, rated 450°C and 300 Vac with a Horizontal flame classification, covering 24 AWG to 4 AWG, solid or stranded. Its base construction is non-extruded mica tape or a mica composite, with a glass braid treated with silicone varnish or TFE finish. The Style also lists an optional construction: stainless steel, alloy 304, applied as a braid over the treated glass braid.
This page covers that optional SS304 braid: what the Style record says about it, where it sits in the construction, and what it does not establish, together with the base mica and glass-braid requirements it is applied over. For the broader Style overview, see the UL 5128 Mica Wire category.
Verified UL 5128 Technical Specifications
| Parameter | UL AWM Style 5128 record |
|---|---|
| Style | 5128 |
| Description | Single or Multiple conductor with other-than-extruded insulation |
| Rating | 450°C, 300 Vac, Horizontal flame |
| Conductor range | 24 AWG – 4 AWG |
| Conductor form | Solid or stranded |
| Insulation | Non-extruded Mica tape, or Mica composite (see facing page) |
| Thickness, 24–12 AWG | Total mica tape layers 15 mils min avg; treated glass braid 7 mils min avg |
| Thickness, 11–4 AWG | Total mica tape layers 20 mils min avg; treated glass braid 15 mils min avg |
| Braid treatment | Silicone Varnish or TFE Finish |
| Optional SS304 braid (Shield entry) | Stainless steel, alloy 304, applied as a braid over the treated glass braid |
| Optional assembly | Two or more conductors cabled together, max O.D. 1.500 inches; mica glass binder and/or fiberglass fillers; optional overall treated glass braid |
| Marking | General |
| Use | Internal Wiring of high-temperature equipment where not subjected to repeated flexing and protected from mechanical abuse. (The acceptability, including current-carrying capacity, has been determined by Underwriters Laboratories Inc.) |
Four points in this table need clarification. First, the SS304 braid is optional; the record gives no thickness, coverage or wire-size requirement for it. Second, all mica and glass-braid values are minimum averages; the record states no minimum-at-any-point value. Third, the record does not state a conductor material or plating; these are confirmed according to the qualified ordered construction. Fourth, the voltage rating is 300 Vac only; no DC or peak value is stated.
Optional Stainless Steel Alloy 304 Braid
The Shield entry of Style 5128 reads: “Optional. Stainless steel, alloy 304, applied as a braid over the treated glass braid.” That wording fixes four things:
- It is optional. A Style 5128 construction may be supplied with or without it. A construction without the SS304 braid is a complete Style 5128 construction, not a reduced one.
- The material is stainless steel, alloy 304. The Style names the alloy; no other metal is listed for this option.
- The form is a braid. It is applied as a braid, not as a tape, wrap or tube.
- The position is over the treated glass braid. It sits outside the mica insulation and outside the treated glass braid, as the outermost layer of that construction.
The record says nothing further. It does not specify braid coverage, wire diameter, number of carriers or ends, braid angle or the finished diameter with the braid applied. It also does not assign the braid any performance. No EMI attenuation, shielding effectiveness, noise reduction, measurement or signal-integrity benefit, abrasion, crush or tensile performance, corrosion rating or thermal protection is established by the Style, and none is claimed here. General material data for alloy 304 are not transferred to the wire.
The optional SS304 braid is therefore a construction choice, specified when the purchaser’s drawing or specification requires that qualified construction. It is not presented here as necessary or preferable for any particular application. Because it adds a layer, finished dimensions, marking and documentation for a braided construction are confirmed for that ordered construction.
Base Mica and Treated Glass Braid Construction
Under the optional SS304 braid, and in every Style 5128 construction, the base construction is:
- Insulation: “Non-extruded Mica tape (see below), or Mica composite (see facing page).”
- Glass braid: a glass braid treated with silicone varnish or TFE finish, with a minimum average thickness set by size group.
The “facing page” referenced for the mica composite is not part of the data used here, so the composite’s makeup is not described. The record does not identify mica type, grade, origin or composition. The Style is described as “other-than-extruded insulation”; it is not described as MI cable, mineral-insulated metal-sheathed cable, magnesium-oxide cable or ceramic cable, and none of those terms applies here.
24–12 AWG — 15/7 Mil Construction
For 24 AWG through 12 AWG, the Style requires:
- Total mica tape layers: 15 mils (0.38 mm by unit conversion) minimum average.
- Treated glass braid: 7 mils (0.18 mm by unit conversion) minimum average.
“Total” means the combined thickness of all mica tape layers. “Minimum average” means the average of that thickness must not fall below the stated value. Neither figure is nominal, exact or typical, and neither is a minimum at any point. The actual thickness of an ordered construction may exceed these values.
11–4 AWG — 20/15 Mil Construction
For 11 AWG through 4 AWG, the Style requires:
- Total mica tape layers: 20 mils (0.51 mm by unit conversion) minimum average.
- Treated glass braid: 15 mils (0.38 mm by unit conversion) minimum average.
These are also minimum averages. The record does not attribute greater dielectric strength, mechanical protection or service life to the larger group’s values, and none is inferred. The finished outside diameter, with or without the optional SS304 braid, is not derived from conductor size and these thicknesses; where a drawing controls it, it is confirmed for the ordered construction.
Silicone Varnish or TFE Finish
The Style describes the braid as “Glass braid treated with Silicone Varnish or TFE Finish.” Both treatments are permitted, and the Style does not rank them. They are finishes on the glass braid, not primary insulation: silicone varnish is not silicone rubber insulation, and TFE finish is not PTFE insulation. The record makes no statement about their relative flexibility, cost, abrasion or heat behaviour. Where a drawing requires one treatment, it is confirmed for the ordered construction.
450°C / 300 Vac / Horizontal Flame
The rating field reads “450 deg C, 300 Vac, Horizontal flame.” 450°C is the rated temperature; the record does not describe it as continuous, sustained or long-term, and no service life is inferred. 300 Vac is the only voltage rating; no DC, peak or higher AC value applies. Horizontal flame is the flame classification; it is not VW-1, FT1 or FT2, and no vertical flame rating forms part of the Style.
The ratings apply equally to constructions with and without the optional SS304 braid. Style 5128 is its own Style with its own construction record; it is not described here as a variant of any other mica Style.
Internal Wiring Use, Flexing Restriction and Mechanical Protection
The Use reads: “Internal Wiring of high-temperature equipment where not subjected to repeated flexing and protected from mechanical abuse. (The acceptability, including current-carrying capacity, has been determined by Underwriters Laboratories Inc.)”
- Internal wiring of high-temperature equipment: the Use does not name specific circuits, sensors or equipment types, and none is designated here. Suitability for a particular circuit is determined from the actual conductor, circuit and equipment requirements.
- No repeated flexing: the wire is not a flexible, moving, robotic, drag-chain or high-flex cable, and no bend radius or flex life is given.
- Protected from mechanical abuse: this condition applies whether or not the optional SS304 braid is fitted. The braid does not make the wire acceptable for exposed locations, field, building, tray, outdoor or direct-burial use.
- Current-carrying capacity: the Use places this within UL’s determination of acceptability. No ampacity or current figure is published for any size, and the Style is not characterised here as a signal-only or low-current Style.
The Style also allows an optional multiple-conductor assembly: two or more of the conductors described above, cabled together with a maximum O.D. of 1.500 inches, with a mica glass binder and/or fiberglass fillers and an optional overall treated glass braid. That construction is covered on the dedicated UL 5128 multi-conductor product page.
What Style 5128 Does and Does Not Define
The Style record defines the rating (450°C, 300 Vac, Horizontal flame); the conductor range and form (24–4 AWG, solid or stranded); the insulation (non-extruded mica tape or mica composite); the mica and treated-glass-braid minimum averages for each size group; the braid treatments; the optional SS304 braid over the treated glass braid; the optional assembly; the marking field (General); and the Use.
The Style record does not define:
- SS304 braid coverage, wire size, construction or thickness
- any shielding, mechanical or thermal performance of the SS304 braid
- conductor material, plating or strand construction
- conductor resistance or current rating
- minimum-at-any-point thicknesses
- finished outside diameter or tolerance
- mica type or the composition of the mica composite
- bend radius, flex life or service life
Common Procurement Errors
- Assuming every Style 5128 construction includes the SS304 braid.
- Omitting whether the SS304 braid is required, leaving the construction undefined.
- Attributing EMI, measurement, abrasion or thermal benefits to the SS304 braid.
- Treating the SS304 braid as removing the mechanical-protection requirement.
- Treating mica or braid thickness values as nominal or point minimums.
- Assuming a conductor material or plating.
- Assigning a current rating to any size.
- Describing the rating as continuous or adding a DC value.
How to Specify UL 5128 with Optional SS304 Braid in an RFQ
The Style fixes the rating, the conductor range and forms, the insulation options, the thickness schedule, the braid treatments, the optional SS304 braid and assembly, and the Use. The following should be stated by the buyer and confirmed for the ordered qualified construction, not filled with assumed values:
- AWG size within 24–4 AWG
- solid or stranded requirement
- conductor material and finish requirement
- detailed strand construction, if controlled
- non-extruded mica tape or qualified mica-composite requirement, if controlled
- treated glass braid finish requirement, if controlled
- optional stainless steel alloy 304 braid required: yes / no
- finished OD or tolerance, if controlled
- single or multiple conductor requirement
- assembly details, if multiple conductor
- marking requirement
- quantity
- packaging
- documentation requirements
- equipment type
- internal routing position
- mechanical-protection conditions
- confirmation that repeated flexing is not involved
UL Marking and Documentation
Style 5128 wire is supplied as UL-recognized component wire where supplied under qualified manufacturing scope. The marking field of the Style record reads “General”; it does not prescribe a fixed legend, method or interval. UL marking is applied according to the confirmed ordered construction, including whether the optional SS304 braid is present, and should be confirmed at the order stage.
Applicable RoHS / REACH documentation can be confirmed according to the ordered construction. CE, UKCA, CSA, FT1, VW-1, CPR, VDE, DIN, EN and IEC are not declared for this product.
Commercial, origin, compliance and transport documents are identified during quotation and confirmed according to the order.
