aluminum backed insulation carrying voltage

[hohmer]

I've got a wall with aluminum backed fiberglass insulation. The aluminum backing is carrying 3v (when I test from anywhere on the backing to neutral on a non equipment grounded outlet). The 3 metal boxes all read 0v when I test them so I don't think they are the culprit. Could the cloth insulated wire in the wall be delivering the 3v (phantom voltage leaking through the cloth insulation)?

 

[ron]

Start by being sure you have a good low impedance meter

https://www.nema.org/Technical/Documents/Bull_88_reaffirmed_12_15_11.pdf

 

[petersonra]

it is possible that just through voltage drop alone you could have 3 Volts between a neutral and an equipment ground.

 

[jaggedben]

The 3 metal boxes all read 0v when I test them so I don't think they are the culprit.

Are you testing them to the neutral or to the insulation?