I don't believe that. Yesterday I was demonstrating that to my son and an electrical engineer who was my customer. The engineer saw the t-pro tester my son had out and commented on the low z feature of it. I opened a load center up , and had the kid test between one of the feed lugs for the ungrounded conductor to the (now turned off) circuit breakers with the load wires attached. Brand new receptacle outlet circuits- no loads plugged into any outlets, he got readings of 115 volts using the Fluke T-pro with its built in low z feature. I put my knopp tester across the exact same points and it read zero volts. Because there was zero actual potential. The both instruments have their good points and their bad points. You don't get replaceable leads with the know, and eventually the leads will wear out. However , there is no chance of a phoney baloney voltage reading where no real voltage is actually present when using a Knopp solenoid tester. The T-PRO will still show phantom voltage readings, low z function or no low z function.
