No one in the insurance game is going to answer that in any other way then you have a responsibility to act legally. As explained previously every policy is different, every claims officer / manager / investigator / assessor (experienced or inexperienced) will have a different opinion.
But whilst every policy is going to be different, all insurance policies are based on "utmost good faith"
If state legislation requires an electrician to install something and you don't, you could void your policy. It would be rare, but remember your dealing with insurance companies, if they can get out of a $200k loss do you really think they wont try?
As for Pushka, im sure if they had gone to the assessor and said "wow, I don't know why the aircon caught fire, I installed it myself" they might have had a different approach. The beauty is that a fire will generally destroy all the evidence.
I've been to the fire's and have seen the investigators / assessors / adjustors... they wont just be there when you are and they will look for all the relevant information.