DIFFERENCE SPT 1 & SPT 2
What is the difference between SPT 1 and SPT 2 ?
When you are looking online at Christmas light stringer wire have you ever noticed the SPT designation? It's merely an indicator of the thickness and durability of the insulation. Most of the time, it may not be even listed as a specification. If it's not, you can almost always assume that it is SPT-1.
SPT 1 wire is a lighter-duty wire rated at 7 amps. SPT 2 wire has a thicker insulation and is rated at 10 amps.
SPT 1 - (top wire) rated at 7 amps / SPT 2 - (bottom wire) thicker insulation rated at 10 amps
If you are using SPT 1 wire, make use you use SPT 1 plugs. Same goes for SPT 2 wire, make sure you use SPT 2 plugs.
Note: Most all Christmas lights bought at big box stores use SPT 1 wire.