SFF-2 / SRML Fiberglass-Braided Silicone Lead Wire, 150°C 600 V

SFF-2 / SRML is a single-conductor, fiberglass-braided silicone lead wire for internal wiring where a 150°C temperature rating and a 600 V voltage rating are required. A flexible tinned-copper conductor carries the circuit; extruded silicone provides insulation; a finished glass braid protects the insulated wire. The supplied size schedule runs from 18 through 6 AWG. Smaller 18–12 AWG configurations use a 0.030 in nominal silicone wall, 10 AWG uses 0.045 in, and 8–6 AWG uses 0.060 in. This change in wall thickness affects the outside diameter and the applicable AWM style. Related high-temperature cable constructions: High Temperature Cables.

Select the wire by both the conductor size and the UL designation. The supplied 18–12 AWG construction aligns with UL 3070 and UL 3231; 8–6 AWG aligns with UL 3127 and UL 3231. UL 3069 applies to a smaller 26–20 AWG range and should not be assigned to the 18–6 AWG table. The exact UL-certified style, temperature rating and marking are specified with each orderable configuration. This distinction matters when a motor, appliance or fixture drawing calls out a particular style number rather than only a generic high-temperature lead wire.

For a 200°C requirement, compare the separate UL 3074 braided silicone wire or another rated construction. For large aramid-covered motor leads, see the UL 3410 family. Send the required AWG, color, length and equipment drawing with an RFQ so the quoted size and certification marking match the installation.

SFF-2 / SRML layer sequence

1. Conductor: flexible stranded, tin-coated annealed copper. The supplied 18–10 AWG specification calls out Class K stranding; 8–6 AWG calls out Class H stranding.
2. Insulation: extruded silicone rubber, with nominal wall increasing by size as shown in Specifications.
3. Outer covering: fiberglass braid treated with a high-temperature finish. This is glass braid, not the polyaramid braid required by UL 3410.

The source specification lists a 0.006 in nominal glass-braid wall for 18–10 AWG and 0.015 in for 8–6 AWG. Colour options can be stated during quotation; no stock-color promise is implied.

Where to use 150°C SFF-2 / SRML

Typical selection contexts are internal appliance wiring, fixture wiring, motor leads and electrical-equipment leads where silicone insulation and an abrasion-protecting glass braid are appropriate. The 600 V and 150°C limits apply to the listed configuration; an application above 150°C calls for a different rated lead wire. The finished braid also helps keep the insulation covered during routing through equipment, but it does not make the cable a mechanical armour or a power cord for repeated movement.

Selection question: does the drawing require a specific AWM style, an SFF-2 fixture-wire type, or simply 150°C/600 V construction? Match the marking and AWG in the specification table before choosing an interchangeable part.

For a large 200°C single-conductor motor lead with an aramid rather than glass braid, compare UL 3410 aramid-braided motor lead wire. For several 200°C circuits in one silicone-insulated, aramid-braided assembly, see SRG-K multicore silicone-aramid braided cable.

Where a motor-lead drawing asks for 1000 V AC at the same 150°C grade, the UL 3580 silicone motor lead is a separate style intended for motor leads and internal appliance or electronic equipment wiring.

SFF-2 / SRML 150°C, 600 V configurations

Nominal reference dimensions; confirm final manufacturing tolerance and marking on the quotation. Thickness and OD are inches; weight is lb per 1,000 ft.

UL 3069: its official AWM size range is 26–20 AWG at 150°C/600 V. No dimensions for those sizes appear in the supplied PDF, so they are not mixed into the table above. UL 3101 is the 10 AWG 150°C/600 V glass-covered style family, but it is not asserted for the specific 10 AWG row without a matching production marking.

Metric equivalents: values marked ≈ are approximate conversions of the supplied nominal inch and lb/1,000 ft data, rounded to 0.01 mm and the nearest kg/km. They are not independent manufacturing tolerances or newly measured specifications.

UL designations by configuration

This UL-certified product family is specified by its actual wire size and marked type. SFF-2 is a 150°C/600 V fixture-wire type. UL 3070 applies to 18–12 AWG glass-covered silicone wire; UL 3127 applies to 8–2 AWG stranded glass-covered silicone wire; UL 3231 allows 150°C or 200°C single-conductor silicone wire with glass or aramid covering. The offered rows on this page are the 150°C glass-braided configurations shown above. UL 3069 is a distinct 26–20 AWG style and is not applied to the 18–6 AWG rows.

The applicable construction standard for the numbered AWM styles is UL 758. Specify the exact UL style and marking with the AWG when requesting documentation.