What kind of electroporator are you using? Exact settings are going to vary by company. I think most companies should have a protocol to follow that helps you narrow down settings. I'd recommend doing this even if someone responds with a setting, just because cell lines and reagents can vary by lab and over time. I've had to re-optimize for cell lines that have already been previously optimized in the past because of this reason.
Previously I applied electroporation to transfection of vector by Bio-Rad Machine. On that time, first I fellow Bio-Rad protocol but the result was not good. Then I started to do Optimization on Electroporation parameter ( take a 1 month ), After this, I could transfect successfully by high rate and efficiency. There is a some critical point(s) in order to use electroporation. First, your passage number of your cells should be low meaning do not use cells with high passage number. Second, The buffer is very important ( I used complete media instead of Bio-Rad reagent). Third, the temperature of electroporation( I used both in room temp and ice bath ).
Totally, Electroporation of each cell line should be optimized to have high efficiency.
You can find optimization parameters from various paper and articles and then draw table with a specific range for each parameters. Among, them Number of pulse is very important and type of wave length.