Paul wrote:

Any silicone (RTV) that I've worked with is a good insulator when fully
cured.
I wouldn't be surprised if it is somewhat conductive before it is
cured, but I never checked.
I never apply voltage until it is fully cured.

Paul

Standard GE RTV silicone contains acetic acid which can cause
corrosion. They do make an electronic grade that is safe to use.

I once used standard RTV to cover the line voltage terminals on a power
transformer. I plugged it in before it was fully cured. This caused a
small explosion.which was more exciting than it was dangerous.