When a character resists electric shock damage, they roll Body plus Willpower plus half Impact armor plus full Nonconductivity rating plus "other factors".

Does trollskin count as a point of impact armor? (Experiment to test the question: try zapping a few trolls who have had their natural skin replaced... consensually, or darn carefully!)

Does Toughness help?

Any other boundary cases, eg things which MIGHT count but not obviously?

Bonus points for posts from people experienced in management of shock hazards.

Firstly, electrical damage is rested with Body + Half Impact, no Willpower on the damage resistance. After damage resistance, if damage was inflicted on the target, a Body + Willpower + Half Impact (3) test is made to determine how long the target is incapacitated. Non-conductivity armor modification applies to both tests.

I would apply Troll natural armor to this test as well. And Toughness would apply to the damage resistance but not the subsequent test.

Yes, troll's dermal deposits are a +1/+1 bonus to all armor. Toughness would not help, this is not a damage resistance test, but a secondary effects resistance test.

Things which might count? People fully enclosed by metal (maybe complete 6 cyberlimb replacement?)?

Edit for clarification:

On the damage resistance roll, they would get body + half impact (including troll armor, cyberware armor, helmets, orthoskin and dermal plating/sheathing) + nonconductive + toughness for damage resistance.

IF they fail that, they resist secondary effects as in my original post.