I love my induction hot plates. I generally do 3 gallon brews so my wort is about 4 gallons. You can use them anywhere without danger of fire.
The cheapest setup which works very well is - 1800w plates ( the largest you can use at 120V) which I found on Amazon for $66 each and graniteware 34 quart stock pots which have magnetic steel. I insulated these by wrapping each pot with folded over bath towels tied with belt. One of the great things is that they can't burn with induction. I put ball valves on them for convenience. Mash tun has mesh filter.
Put mash tun on burner and heat to strike temperature. Takes a little while.
At strike temperature dump grain. Set induction plate to very low to keep mash temp constant.
Meanwhile, in wort boil kettle heat water to sparge temperature
BAtch sparge in usual way.
Transfer wort to boil kettle set induction plate to highest temp. Wort boils pretty quickly because wort from mash tun is quite hot. lower temp setting to low prevent boil over.