Hi,
Chances are it will be approximately 16 gauge. If you can, take a pic of the wiring and upload it so I can see it. I should be able to get close to the size. When you purchase the connectors, they usually will fit a few different sizes which are close together. For example, on connector will fit 16, 18 and 20 gauge.
Also, most of these connectors are different colors based on size. Let me know what color the connector is you used. That may help as well.
Let me know.
Joe
Jul 8, 2020 at 8:42 PM