720Deere wrote:
It doesn't much matter if the main breaker is off if you have a fault somewhere and end up energizing the neutral.
A cheapo interlock isn't going to help with that problem either, being a purely mechanical device. A computerized transfer switch (read $$$$$) might detect that fault condition, it might not.
I guess that's where the sparky and your local code enforcement agent come into, adding to the $$$$$ but hopefully one of them checks to see if that fault exists.
$2-3000 on sparky, permits, etc is cheaper than a multi-million dollar civil suit judgement for manslaughter but I guess I'm a gamblin man!