I can't do a decoction in my electric system- the element is at about the three gallon level for one thing, plus I wouldn't want grain in contact with the element anyway.
For decoctions, I use my kitchen stove since my brewery is in my laundry room. It's not too bad, but it's certainly not ideal!
If my system was outdoors, I'd probably have a small propane burner in it somewhere for decoctions.
Broken Leg Brewery
Giving beer a leg to stand on since 2006