UL 3304 vs UL 3573 Ignition Wire — Which AC High Voltage Wire for Your Application
UL Style 3304 and UL Style 3573 are both AC high voltage ignition wires rated 200°C and 10,000 Vac under UL Subject 758 — and they serve the same fundamental application: internal wiring of electronic ignition systems in gas ranges and gas or fuel oil burner systems. The difference between them is not voltage rating or temperature rating — it is construction. Style 3304 uses a single fiberglass braid outer covering over silicone rubber insulation. Style 3573 adds an outer silicone rubber jacket over the fiberglass braid, creating a dual-layer protection system.
Whether this construction difference justifies specifying Style 3573 over the simpler Style 3304 depends entirely on the installation environment and service access frequency. This comparison provides the technical basis for that decision.
UL 3304 vs UL 3573 — Full Parameter Comparison
| Parameter | UL 3304 | UL 3573 |
|---|---|---|
| UL Style | 3304 | 3573 |
| Temperature Rating | 200°C | 200°C |
| Voltage Rating | 10,000 Vac | 10,000 Vac |
| Flame Rating | Horizontal flame | Horizontal flame |
| AWG Range | 22–12 AWG | 22–12 AWG |
| Primary Insulation | SR-Silicone — 40 mils min average / 36 mils min at any point | SR-Silicone — 30 mils min average / 27 mils min at any point |
| Intermediate Layer | — | Fiberglass braid |
| Outer Covering | Fiberglass braid | Outer silicone rubber jacket |
| Total Layers | 2 (silicone + fiberglass braid) | 3 (silicone + fiberglass braid + silicone jacket) |
| Outer Surface | Fiberglass braid texture — rough, absorbent | Smooth silicone rubber — cleanable, grease resistant |
| Overall Diameter | Smaller — single braid outer | Larger — additional outer jacket layer |
| UL Use Description | Gas ranges and gas or fuel oil burner systems | Gas ranges and gas or fuel oil burner systems |
| UL Recognition | UL Recognized Component — file on record | UL Recognized Component — file on record |
Construction Difference — What the Extra Layer Actually Does
The defining difference between Style 3304 and Style 3573 is the outer silicone rubber jacket on Style 3573. Understanding what this jacket adds — and what it does not add — is the key to making the correct specification choice.
What the outer silicone jacket adds:
- Smooth, cleanable outer surface: Style 3304’s fiberglass braid outer surface is porous and absorbent — it traps cooking grease, food residue, and cleaning agent residue in the braid interstices. Over time in commercial kitchen environments, the braid surface becomes contaminated and increasingly difficult to clean. Style 3573’s outer silicone rubber jacket provides a smooth, non-porous surface that wipes clean with a damp cloth and resists grease absorption — maintaining a clean outer surface throughout the wire’s service life in food contact adjacent environments.
- Additional mechanical protection layer: The outer silicone jacket of Style 3573 provides a second mechanical protection barrier over the fiberglass braid, adding abrasion resistance for wire routing paths where the ignition lead repeatedly contacts metal enclosure edges during appliance opening, servicing, and cleaning cycles. In residential gas ranges where the cooktop is lifted for cleaning access several times per year, the ignition lead at the cooktop hinge routing point experiences repeated mechanical contact — the outer silicone jacket of Style 3573 is more durable in this position than the bare fiberglass braid of Style 3304.
- Chemical resistance: Silicone rubber resists common kitchen cleaning agents including alkaline degreasers, acidic cleaners, and sanitizing chemicals that can degrade fiberglass braid sizing and weaken the braid structure over repeated cleaning exposure. Style 3573’s outer silicone jacket maintains its mechanical integrity in cleaning chemical environments where Style 3304’s exposed fiberglass braid may degrade over time.
What the outer silicone jacket does NOT add:
- Additional voltage rating: Both styles are rated 10,000 Vac. The outer jacket of Style 3573 does not increase the voltage rating — the primary silicone rubber insulation provides the dielectric barrier in both styles.
- Additional temperature rating: Both are rated 200°C. The outer jacket does not change the thermal rating.
- Reduced primary insulation wall: Note that Style 3573’s primary silicone rubber insulation is 30 mils minimum average — 10 mils thinner than Style 3304’s 40-mil primary insulation. The total insulation system of Style 3573 (30-mil silicone + fiberglass braid + outer silicone jacket) provides equivalent or superior overall dielectric performance to Style 3304 (40-mil silicone + fiberglass braid), but the individual primary insulation layer is thinner. Do not specify Style 3573 in applications where only the primary silicone layer is present without the outer jacket — the jacket is part of the certified insulation system.
Which Style to Specify — Decision Guide
| Application Scenario | Recommended Style | Reason |
|---|---|---|
| OEM factory installation — static routing, no repeat servicing | UL 3304 | Simpler construction, smaller OD, lower cost — adequate for static installation |
| Commercial kitchen gas range — accessed for cleaning regularly | UL 3573 | Smooth outer jacket resists grease and cleaning chemicals |
| MRO replacement — field replacement in existing appliance | UL 3573 | Outer jacket durability advantage for wire subject to repeated handling during servicing |
| Fuel oil burner ignition transformer leads — industrial boiler | UL 3304 | Static installation, no cleaning requirement, 40-mil primary insulation adequate |
| Industrial gas burner — chemical/grease exposure at routing path | UL 3573 | Silicone jacket resists chemical exposure and grease contamination |
| Space-constrained routing — tight conduit or narrow channel | UL 3304 | Smaller overall diameter — easier to route through tight spaces |
Summary — One Sentence Each
Specify UL 3304 when the ignition lead is installed once in the factory, routed in a static position, not subject to repeated cleaning or mechanical contact during service access, and overall wire diameter is a routing constraint.
Specify UL 3573 when the ignition lead will be accessed repeatedly during appliance cleaning or servicing, routes through positions where grease or cleaning chemical contact is likely, or requires the additional mechanical protection of the dual-layer construction for long-term MRO durability.
Both styles carry identical voltage and temperature ratings — the choice between them is purely about installation environment and service access requirements, not electrical performance.
Request a Quote — UL 3304 or UL 3573 Ignition Wire
Submit your AWG, required style (3304 or 3573), quantity, and annual volume estimate below. Our team responds within 12 business hours. Free samples of both styles available for side-by-side comparison and ignition system qualification testing.