Lets assume for a moment you have the resnode Overlook on ns_veil captured at 1:30. Assuming you don't electrify it, and it holds for 3 minutes because this is the area your marines are generally walking past, you've netted something along the lines of 30 res from it.
Assuming you do electrify it, 4:30 or those 3 minutes is the moment you've netted ZERO res from it - 4:30 incidentially being the average time for a Fade to complete gestation. The time you're gaining res is the time it takes a Fade to decide to take it down - 1 minute is just about realistic. You'll net 12-15 res from that.
Theres the advantage to that, you've denied the Aliens putting up an RT in that spot - but unless its in a place that would put them at a serious disadvantage, like an alien-friendly node, they won't care. Theres a limit of about 4 RTs you can hold down against decent 'rines anyway - anything outside that is usually not even attempted until the ~8 minute mark at least.
Thats the upside. But the downside to electrification for protection is alot more drastic - it doesn't remove those 30 res you'd have at 4:30, it removes them at 1:30. Thats very, very, very bad in a game providing any challenge at all - those 30 res could be any upgrade, shotguns or an AA or any other item you need fast before Aliens get the chance to expand. Early electrification shoots itself in the foot - electrification only being useful against largely dominated alien teams to avoid comebacks, but hampering map-domination in itself.
So the main uses of Electrification that remain :
- Base defense, great for crowded spots
- Limiting the options of 1-Hive aliens
- Boosting TFs, especially important ones on the offense (and/or defending a TFs Sieges. Its decent for Sieging as it requires no building)