The main as well as the sub inside the home both had white fuzzy stuff growing inside. Does anyone have any ideas what it could be?
wire pulling lube that has dried up…Just a guess.
Or foam sealer.
yep, looks like spray foam from the pic. Looks like the panel is outdoors, so they spray foamed the cable entrance holes to keep air/critters out.
Just a guess…
Ain’t working too well is it? :mrgreen:
Too white and too soft to be foam insulation…I think. The sub panel in the house had some spray foam and some of this white stuff…
You know what questions coming next… “Did you lick it”? 
What about the 1/0 wire to the grounding buss bar? Looks like several strands are cut.
Caterpillar nests?
DAP makes a white latex spray foam that looks just like that.
I was thinking since it looks like a nesting was in this, someone sprayed in at the KO with a foam spray killer.
http://www.domyownpestcontrol.com/foaming-products-c-302.html