We get asked this question all the time! There is a lot of confusion and misinformation out there on the difference between SPT-1 and SPT-2 wire. I'd like to answer this question in terms of Christmas light installations.
What is the difference between SPT-1 and SPT-2? It's simply that SPT-2 has thicker insulation on the wire. That's it! They both use 18awg wire, therefore, share the same electrical properties. It's only thicker insulation that separates these two products.
What does this mean in the Chrsitmas world? Generally speaking, you are better off using SPT-1 wire, because it costs a little less than SPT-2. In fact, we don't even carry SPT-2 because the demand is so low. Using SPT-2 with a thicker insulation doesn't really gain you much in the world of Christmas light installations. The electrical properties are the same, so there isn't a real gain.
When should you use SPT-2? The thicker insulation of SPT-2 could come in handy in situations where the wire could get really brittle. For example, if it was used in extremely cold temperatures, or used in extremely high UV exposure situations. In other words, if you are installing lights in the arctic or at the equator, SPT-2 might be a better selection.
I hope this helps clear up a commonly asked question!
If you are in the need of SPT-1 wire products, please click here to shop our entire line of SPT-1 wire, plugs and sockets.