Scorching is more complicated than a power rating on an element. Most people look at power density: the power on the element divided by its surface area. The common target is low watt density (LWD element) which is 50 watts per square inch. These elements typically either fold back or ripple. I have not heard of anyone scorching wort with one of these LWD elements, but it could be possible. I use a LWD 4.5kW element in my system. I bought the element at Home Depot.
Some other factors that might influence scorching include: how much heat your system loses while recirculating, how fast you can run your pump without compacting your grain bed, if your system is 110V or 220V, and if you need to step mash.