SPT-1 vs. SPT-2: SPT-1 and SPT-2 is a measure of the insulation thickness of traditional 18 AWG cords. SPT-1 is the type most commonly used by commercial Christmas lights installers. SPT-2 is thicker and tailored to harsh weather conditions.. Gilbert plugs must match.
Maximum length: Cut these spools to a maximum of 250 feet. This is the maximum run specification for 18 AWG wire and applies regardless of type of bulb used. Consult with a Master Electrician with any electrical questions.