I completed an inspection on a 33 year old house with aluminum wiring. Before opening the panel, I used my “Ciruit Alert” and covered all four corners of the panel box. I was leaning on a chest freezer directly in front of the panel. The alert indicated a current. I was surprised and tested the box again. This time I did not make contact with the freezer. The alert indicated no current. I have had the unfortunate experience years ago of going dead to ground and woke up in the hospital. In this case I declined to inspect the electrical and wrote up that a licensed electrician should be consulted.