UL 5107 26–12 AWG Mica Wire — 25/7 Mil Construction
UL AWM Style 5107 is a single or multiple conductor with other-than-extruded insulation, rated 200 or 450°C and 600 Vac with a Horizontal flame classification. Its insulation is mica tape with braid, or mica composite with braid, and the required thicknesses are set by conductor-size group. For the 26 AWG to 12 AWG group, the Style requires a minimum average thickness of 25 mils for the total mica tape layers and 7 mils for the treated glass braid.
This page covers that 26–12 AWG construction: what the two minimum-average requirements mean, how the braid treatment is worded, which conductor forms apply, and what the Use permits. The full 26 AWG–550 kcmil range appears only as a brief reference. For the broader Style overview, see the UL 5107 Mica Wire category.
Verified UL 5107 Technical Specifications
| Parameter | UL AWM Style 5107 record |
|---|---|
| Style | 5107 |
| Description | Single or Multiple conductor with other-than-extruded insulation |
| Temperature | 200 or 450°C |
| Voltage | 600 Vac |
| Flame | Horizontal flame |
| Page-specific conductor range | 26 AWG – 12 AWG |
| Complete Style conductor range | 26 AWG – 550 kcmil |
| Permitted conductor forms | Solid or stranded for 26 – 8 AWG; stranded only for sizes larger than 8 AWG |
| Insulation | Mica tape with braid, or Mica composite (see Facing Page) with braid |
| Mica thickness, 26–12 AWG | 25 mils (0.64 mm) minimum average thickness of total mica tape layers |
| Braid thickness, 26–12 AWG | 7 mils (0.18 mm) minimum average thickness of treated glass braid |
| Braid treatment | Silicone Varnish or TFE Finish |
| Marking | General |
| Use | Internal Wiring of high-temperature equipment where not subjected to repeated flexing and protected from mechanical abuse, and where the acceptability, including current-carrying capacity, has been determined by Underwriters Laboratories Inc. |
Four points in this table need clarification. First, the millimetre values are arithmetic conversions (1 mil = 0.0254 mm), not separate UL specifications. Second, both thickness values are minimum averages; the record states no minimum-at-any-point value for either layer. Third, the temperature rating is expressed as 200 or 450°C; the record does not tie either rating to a particular braid treatment or mica material. Fourth, the record does not state a conductor material or plating; these are confirmed according to the ordered qualified construction.
25 Mil Minimum-Average Total Mica Tape Layers
The Style’s wording for this requirement is “Min average thickness of total Mica tape layers,” and for 26–12 AWG the value is 25 mils (0.64 mm by unit conversion). Two words in that phrase define what is measured.
- “Total”: the requirement applies to the combined thickness of all mica tape layers, not to a single tape.
- “Minimum average”: the average thickness of those combined layers must not fall below 25 mils.
The record gives no minimum-at-any-point value for the mica layers, and none is added here. The 25-mil figure is not a nominal, exact or finished thickness, and no tolerance is attached to it. The actual thickness of the mica layers in an ordered construction may exceed 25 mils; the Style sets only the floor for the average.
The record also does not specify the number of tape layers, tape width, overlap or wrapping pattern. Those are construction details of the qualified ordered construction, not Style-level parameters.
7 Mil Minimum-Average Treated Glass Braid
Over the mica layers is a glass braid. For 26–12 AWG, the Style requires a minimum average braid thickness of 7 mils (0.18 mm by unit conversion). As with the mica layers, this is a minimum average only; no minimum-at-any-point value is stated, and 7 mils is not a nominal or finished braid thickness.
The record describes the braid as “Glass Braid Treated with Silicone Varnish or TFE Finish.” Either treatment is permitted by that wording. What the record does not do is assign a treatment to a temperature rating. It does not state that one treatment corresponds to 200°C and the other to 450°C, and this page does not create that link. Which treatment applies to an order is confirmed against the qualified construction for the ordered temperature rating.
The treatment is a finish on the glass braid. TFE finish is not PTFE primary insulation, and silicone varnish is not silicone rubber insulation. The record also does not define yarn size, braid angle or coverage, and it attributes no abrasion, moisture or other performance to the braid or its treatment.
Mica Tape with Braid or Mica Composite with Braid
The Style’s insulation entry reads: “Mica tape with braid, or Mica composite (see Facing Page) with braid.” Two insulation systems are therefore permitted, and both include a braid. The thickness table in the record is headed by mica tape layers and the treated glass braid.
The record refers to a “Facing Page” for the mica composite. That page is not part of the data used here, so the composition of the mica composite is not described on this page. Where a drawing specifies mica composite rather than mica tape, the requirement should be stated in the RFQ and confirmed against the qualified construction.
The record does not identify the mica type, grade, source or purity. No mica variety is named here, and no temperature performance is attributed to any particular variety.
200°C or 450°C at 600 Vac
The rating field reads “200 or 450 deg C, 600 Vac, Horizontal flame.” The Style carries two alternative temperature ratings; a given construction is qualified at one of them. The rating that applies to an order is confirmed for the qualified ordered construction. Neither rating is described in the record as continuous or long-term, and no service life or thermal margin is derived from either.
600 Vac is the only voltage rating in the record. No DC value or combined AC/DC figure applies.
Horizontal flame is the flame classification in the record. It is not VW-1, FT1 or FT2, and no vertical flame rating forms part of the Style. The 25/7 mil requirement for 26–12 AWG is the same at either temperature rating.
26–12 AWG Solid or Stranded Construction
The conductor field reads “26 AWG – 550 kcmil. Solid or stranded for sizes 26 – 8 AWG; Stranded only for larger sizes than 8 AWG.” The whole 26–12 AWG group sits inside the 26–8 AWG band, so both solid and stranded conductors are permitted for every size on this page.
The record does not state conductor material or plating, and it does not define strand count, strand diameter, lay length, conductor diameter or conductor resistance. These are confirmed according to the qualified ordered construction.
Internal Wiring Use, Flexing Restriction and Mechanical Protection
The full Use wording is: “Internal Wiring of high-temperature equipment where not subjected to repeated flexing and protected from mechanical abuse, and where the acceptability, including current-carrying capacity, has been determined by Underwriters Laboratories Inc.” It contains four conditions:
- Internal wiring of high-temperature equipment: the wire is for internal wiring of equipment in that category.
- Not subjected to repeated flexing: it is not a flexible, moving, hinge, robotic or drag-chain cable, and no bend radius or flex-cycle rating applies.
- Protected from mechanical abuse: exposed, open-machinery, outdoor, field, building, tray and direct-burial routing fall outside the Use.
- Acceptability determined by UL, including current-carrying capacity: current capacity is not a Style-level figure. It belongs to the determination for the application, so no ampacity or current rating is given here, and none is calculated from conductor size.
Other UL 5107 Thickness Groups
For reference, the complete thickness schedule of the Style is shown below. This page covers only the first group.
| Conductor size group | Total mica tape layers, min average | Treated glass braid, min average |
|---|---|---|
| 26 – 12 AWG (this page) | 25 mils | 7 mils |
| 11 – 4 AWG | 30 mils | 15 mils |
| 3 – 4/0 AWG | 35 mils | 20 mils |
| 250 – 550 kcmil | 40 mils | 20 mils |
Two points in this table need clarification. First, each group’s values apply only to that group; the 25/7 mil values do not extend to 11 AWG and above. Second, all values in the schedule are minimum averages, and none is a minimum at any point.
The Style also allows, as independent options, two or more insulated conductors cabled together with a maximum assembly O.D. of 1.500 inches, with a mica glass binder and/or fiberglass fillers; a shield of 36–30 AWG strands; and a treated glass braid over the assembly. These options are covered on the dedicated UL 5107 multi-conductor product page and are not part of this page’s single-conductor 26–12 AWG construction.
What Style 5107 Does and Does Not Define
For the 26–12 AWG group, the Style record defines the rating (200 or 450°C, 600 Vac, Horizontal flame); the permitted conductor forms (solid or stranded); the insulation systems (mica tape with braid, or mica composite with braid); the 25-mil minimum average of total mica tape layers; the 7-mil minimum average of treated glass braid; the braid treatment options (silicone varnish or TFE finish); the marking field (General); and the Use with its conditions.
The Style record does not define:
- conductor material, plating or strand construction
- conductor resistance or current rating
- minimum-at-any-point thicknesses
- finished outside diameter or tolerance
- mica type or grade, or the composition of the mica composite
- which braid treatment applies to which temperature rating
- number of tape layers, yarn size or braid construction
- bend radius, service life or colour
Common Procurement Errors
- Treating 25 mils or 7 mils as nominal or finished thicknesses.
- Adding minimum-at-any-point values the Style does not state.
- Assuming 200°C means silicone varnish and 450°C means TFE finish.
- Naming a mica type as part of the Style.
- Assuming a conductor material or plating.
- Applying the 25/7 mil values to 11 AWG or larger.
- Specifying the wire for repeated flexing or unprotected routing.
- Assigning a current rating by AWG.
- Assuming VW-1, FT1 or another vertical flame rating.
How to Specify UL 5107 26–12 AWG Mica Wire in an RFQ
The Style fixes the rating options, conductor forms, insulation systems, the 25/7 mil minimum averages, the treatment options and the Use. The following should be stated by the buyer and confirmed for the ordered qualified construction, not filled with assumed values:
- conductor size within 26–12 AWG
- solid or stranded construction
- conductor material and finish requirement
- detailed stranding, if controlled
- required temperature rating: 200°C or 450°C
- mica tape or qualified mica composite requirement, if specified
- braid treatment requirement, if specified
- finished OD or dimensional limitation, if controlled
- colour
- marking requirement
- quantity
- packaging
- documentation requirements
- equipment type
- exact internal routing location
- whether the wire is protected from mechanical abuse
- confirmation that the application does not involve repeated flexing
UL Marking and Documentation
Style 5107 wire is supplied as UL-recognized component wire where supplied under qualified manufacturing scope. The marking field of the Style record reads “General” and does not prescribe a fixed print legend. UL marking is applied according to the confirmed ordered construction, including its temperature rating, 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.
