Volt's passive explanation help required

[Grisyn]

How does its damage calculation work? 

Total output = (base damage + serration + 1000 (passive) * elementals? Or total output + 1000 (passive)?

[R4bbit0le]

It's your second option. It's a flat electricity damage added on top of your total output.
It does not benefit from your mods nor does it combine with other elements, it will always be electricity damage.
The passive can be discharged with volt's abilities too and only one instance of it will occur per passive discharge. 
However, like previously stated, critical damage, melee combo counters and sniper combo counters will include this damage in it's calculations and so will enemy defenses and vulnerabilities.
It's not too important since 1000 damage it's nothing significant except for fishing!!

[Pakaku]

As far as the lack of explanation goes, it just seems to be an extra instance of damage at the end of whatever shot you make. No other special calculations besides, as the wiki claims, crit hits and sniper combo counters.

Anyone who actually plays Volt feel free to correct me, though

[(PSN)Sentiel]

It's the latter. You basically get extra flat 1000 Electric damage to your next attack with a separate Status proc too.

It's not affected by mods and doesn't combine with other elements, except for Transistor Shield. It is a Electric Shield augment that transforms the blocked incoming damage into Volt's passive, so it will now charge from another source instead of just being tied to your grounded movement. The added benefit is that it caps on the 1000 nearly instantly so you can keep the extra 1000 damage for most if not all of your attacks as long as you use the Electric Shield well. This also means it can proc the Electric status more often, which in turn buffs all your CO related damage.

[taiiat]

however, note that Crits will affect the Passive, as well as other unique sources of overall Damage increase.