What is SIS/Switchboard Wire?
Construction
SIS wire is composed of a soft annealed solid or stranded tinned copper conductor with a Cross-Linked Polyethylene (XLPE) jacket. SIS Wire is available in a range of sizes from 4/0 to 18AWG. This is standard construction, but you may sometimes find SIS wire with bare copper conductors instead of tinned. SIS Wire is available with both course strand counts and flexible strand counts. It comes in a variety of colors for easy identification, gray being the most common.
It is standard that SIS wires have a temperature rating of at least 90°C and carry the UL VW-1 vertical flame test rating. With the VW-1 rating, the XLPE insulation material resists the propagation of a fire. This applies mainly to applications that involve home appliances. Both temperature and flame test requirements are important to clarify when looking for the type of SIS wire that is best for your project or job.
Dual Ratings
With the ability to be dual rated, SIS Wires meet the standards of UL 3173, UL 3195, UL 3196, or XHHW-2 depending on the gauge size. UL 3173 is dual rated as SIS in sizes 10AWG and smaller, UL 3195 only in 8AWG, and UL 3196 in sizes 6AWG to 2AWG. UL 3173/3195/3196 cables have a temperature rating of 125°C.
Printing on UL 3173/3195/3196 is also dependant on the size of the wire. 14AWG and larger wires are printed with “SIS” for switchboard application use, while 16AWG - 18AWG SIS wires are printed with “Suitable for Switchboard Use”.
For more information on SIS Wire and its specifications, visit our Switchboard Wire & SIS Wire page.