I always thought the standard, as per my Ewa Lawrence book, was 30~32 inches from the bottom of the lamp to the top of the slate. That's how I have mine at home, and it works out great.
62 inches from the base of the lamp is too high, and will produce shadows, IMO.
40 inches would be good, too, as the BCA says. Sounds about right, as well. But don't be afraid to go any lower if you wish, IMO as well.
Proper lighting is no joke.
I rather play on a table with a good amont of roll of and proper lighting as opposed to poor lighting/good table conditions.