Isolation is the best way to avoid surge transients. The article I referred to earlier explains. Good isolation - no discharge. Connecting chassis to logical 0V will bypass that isolation.
Are you sure you don't mean ESD when you say "testing at every opening"? A surge transient is more likely to literally blow things up.
Are you sure you don't mean ESD when you say "testing at every opening"? A surge transient is more likely to literally blow things up.