Re: Ground burning out
I'm of the same thinking as jled96 ---- in that you would use only one tap on the transformer.
Also I'll bet the model you have is the 360 watt model which is why the warning --- currently you have a total of 420 watts .
If the conductors had gotten wet then likely are corroded which increases the resistance of the the load ( which increases the amperage draw from the transformer ). When copper wire ( especially stranded ) gets wet it wicks the corrosion further up the wire. In which case you may need to strip back the covering until you get to good clean copper wire to make your splice.
Also, tape won't do any good trying to keep your splices dry under ground --- they should be in water tight j-boxes.
"" an ounce of perception -- a pound of obscure "