This may be useful or it may not but I figured I'd post it.
There are charts and apps on the web that make this a no brainer but for me I don't have an i phone or computer attached to me so I do it this way.
Everyone has noticed that wire connectors come in a variable range of wire gauges. (22-18AWG, 16-14AWG, 12-10AWG, etc.)
Well, if combining multiple wire gauges together in a splice what gauge connector do you use.
One easy way is to use a wire gauge chart
Wire Gauge Chart.jpg
Using the area of the wire you can find the connector size needed. This works for wires that over lap.
Example:
You want to splice 2-16 gauge wires together. Find the area of 1-16 gauge wire (1,3) multiply that by 2 and you get 2,6. Using the chart find what gauge of wire has the area is closest to 2,6. That looks to be 13 gauge(2,6), If the calculated wire gauge is not available (14-13-12) its better to go with the next smaller wire gauge(if possible) to insure a good crimp, so I would use a splice connector in the 14 gauge range(2,1).