The acetoxy cure silicones, as well as exuding methanoic acid, have rather poor and unspecified dielectric properties. The real stuff, like Dow 738, comes in at 19 kV/mm and, if you can find it, is a better bet than building supplier's neutral cure silicone. If you can find it, it's only £10 for a 100ml tube, but like everything else at the moment there seem to be supply problems - my usual source has a 115 day lead time on it.