Hmm, I don't see why grounded vs. ungrounded should make a difference in the Stetzerizer readings. I'm guessing it is something else (like devices on the branch circuits, or perhaps which phase(s) - legs - the branch circuits are attached to). Do you notice that many areas in your home are lower - around that 150-300 range - and then many other areas are up in that high range? This could be explained by the 2 hot "phases" or "legs" that come in to the house - A and B - they can be quite different in readings.
By base are you talking about the socket boxes for the analog electric meters? We currently do - we have 2 different models of 100 amp sockets. If you need a 200 amp socket, I can point you in the right direction. But as for the 100 amp we have those in stock and can ship them along with your meter(s).
I see that you received your item already - I hope that you like it! That Body Voltage Kit is a very well put-together kit and is very useful.
This order was shipped the very first business day and like with most orders was sent via USPS.com Priority Mail which is delivered in 1-3 days. So the normal expected arrival time for US orders is 1-3 days :)
Customer support service by UserEcho