Question about Conversion

Let's say my skill says it deals "200% damage".

If I use a weapon with 20 phys damage, it means this skill will deal 40 phys damage. If I use gloves with 5 phys damage, skill will deal 50 damage, because base is now 25.

But when the skill says "100% phys damage becomes lighting" - I don't really understand how it works here with added lightning damage. With these wep and gloves I still deal 50 damage and it all converts to lighting, so it is 50 lightning damage.

But what if my gloves add not 5 phys dam, but 5 lightning dam? It, obviously, won't convert, and if so, will it multiply by 200% dam multiplier?

And what if my gloves deal 5 fire dam?

thx a lot -)