Quote Originally Posted by John-Nicholas View Post
In no way would I consider myself an expert... but I do remember seeing someone adding 220 to their shop and they had to replace the plastic conduit with metal and run individual wires. Previously they were going to run romex through the plastic conduit. I do not recall what the issue was (maybe a grounding issues??) but it might be worth looking into.

Another area to consider is the dust collector, is the flexible tube properly grounded?
That would make no difference what's so ever Conduit is Conduit, or what wire you run in it, it is amazing what people will say