Warframe Chroma Electric build range
In many ways the Warframe Chroma is proven to be more superior with melee weapons than range. However if the user persist on using a range weapon I would strongly suggest going on a Electric Elemental Ward + Vex Armor build.
The reasons is simple, a range player should be on the move all the time and avoid as much damage as possible. With that in mind the health boost and fire circle from the Fire Elemental Ward is already not as useful for it. What is good is Shields which is provided by the Electricity Elemental Ward. Note that if it buffs up an extra 100 shield and you constantly get damage and rest for one whole min you could probably do that 5 to 9 times which indirectly gives you a 500 to 900 extra shield buffer.
Using Electric build in an infested mission may not be a very good example, but I believe it's true potential comes from when it is fighting in a normal mission with both range and melee enemies. Chroma can use his gun to focus on killing the range enemies and letting the strong electric damage from Elemental Ward to kill those that comes near him. This way Power Range is not required because you want the Elemental Ward to focus on melee enemies only. With that said Chroma can focus more on Survivability Mods.