A menorah should preferably be within 10 tefachim from the ground (though higher than 3 tefachim). Are these ten tefachim measured to the base of the menorah, or to its top, or to the actual level of the flame (e.g., if glass inserts are used)?
The reasoning is that at that height there is more pirsumei nisa since one who needs the candles for light would normally place it higher. That would seem to indicate that the light (flame) should be at that height. Conversely, a candle hanging down from above 20 amos would be OK accordingly.