I'd guess the same - aggravated by expnsion/contraction of the heat tape cycling on and off. I have seen enough leakage (on a non-GFI Circuit) to give you a tingle when touching gutter downspouts.
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2008 Itasca Meridian 37H & 2015 Flagstaff T12RBST
2011 & 2012 Len & Pat's "One lap of America"
27K miles & 41 states in 13 months - Woo Woo
[SIGPIC][/SIGPIC]Yellowstone Lake 6-1-2012