Append

data.raw["item"]["green-wire"].icon_size = 32
and
data.raw["item"]["red-wire"].icon_size = 32

in data.lua.

Thanks Ajick! : ) I just uploaded with your fix!

It's slightly incorrect.
You should append this lines after setting up "icon" property in "Blue" and "Yellow" branches.
In case of appending this lines in the end of file you can't select other properties of mod settings in Factorio menu.
This is a link to proper version of data.lua: https://pastebin.com/LH8z6qnh

Ohhh !! Sorry.. my mistake.... Now i get it, thanks Ajick!! I uploaded your fix! :)