Can I run my Onan while plugged into shore power?

Seems like this topic comes up monthly. Several schools of thought. I wouldn't do it. Sure the ATS should protect everything but for the 15 seconds it takes to unplug and start the genset, why wouldn't you unplug to mitigate the risk - even if it's a low risk? IF the ATS should fail it's a VERY expensive mistake. There is also differing opinions on having to exercise your genset at all. I do. Most do, but some don't and never have issues. It's also not cut and dry which gets priority, gen or shore power. This can depend on the rig, year, a bunch of factors.

In Short, yes you can. The questions; should you and will it have any benefit? The easiest solution is to unplug before starting the gen and all those questions/concerns become moot.