Cool!
When you say circuit, I am assuming yours are controlled in some manner to come on automatically for different parts of the lawn at different times?
As far as freezing... I don't know much about that either. I heard that the ground freezes from a neighbor (never tried digging it myself) but that may have been from a pro installer telling the neighbor so he could come back each fall to winterize it.
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Rosewood 1983 911 SC Targa | Black 1990 944 S2 | White 1980 BMW R65 | Past: Crystal 1986 944 na
Guards Red is for the Unoriginal