Allied Encyclopedia: UL 3257 Wire


What is UL 3257 Wire?

What is the name of the high temperature and high voltage rating ignition wire may be used for internal wiring in gas-fired heaters? The one and only UL 3527! In this post we will be discussing how UL 3527 is constructed, how it is used and what makes it unique. Let’s take a look!


UL 3257 is a single conductor wire, often referred to as hook up wire or lead wire. UL 3257’s conductor is constructed of stranded nickel plated copper, and is available in a AWG range of 22 AWG to 12 AWG. The insulation of UL 3257 is created from extruded SR, silicone rubber. The most common insulation color of UL 3257 is red but it is available in other colors. The insulation thickness of UL 3257 is thicker than most other wires in its AWG range, with 78 mils min average and 70 mils min at any given point, giving UL 3257 a high voltage rating of 10KV AC to 25KV DC.

The temperature rating of the UL 3257 ignition wire runs from -80°C to 250°C.  UL Style 3257 ignition wire passes the UL horizontal flame test and is covered under the UL Standard Appliance Wiring Material (AWM) Subject 758.

UL 3257 is available in sizes 36-42 AWG as resistance wire, which is spirally wound around a fiberglass core. UL 3257 is approved to be made with an optional covering of treated glass braid, the same covering found on SF-1 Wire.


This wire can be used for the internal wiring in gas-fired heaters and furnaces where it is protected from damage during handling, installation and servicing. Oil-burner ignition circuits and gas appliance ignition systems are other areas that UL 3257 is utilized in and is not subjected to flexing.

For more information about UL 3257 please visit our catalog page. To request a quote on UL 3257 ignition wire  visit our Quick RFQ form or call one of our experienced sales reps today at 1-800-472-4655!

About awcwire
Allied Wire & Cable is a value-added manufacturer and distributor of electrical wire and cable, tubing, and more. We are a family owned and operated company, serving a wide range of industries, including the military, automotive, aerospace, and telecommunications markets. Allied is headquartered in Collegeville, PA. Additional locations can be found across the US, in Merrimack, NH, Tampa, FL, Pewaukee, WI, and Las Vegas, NV. For more information on Allied, visit our main website at

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