The lights of the menorah must be situated at least three tefachim (approximately ten inches) from the floor but no higher than ten tefachim (approximately thirty one inches). It is not the Chabad custom to specifically position them between seven and ten tefachim, or, alternatively, close to three. If someone did light the menorah above ten tefachim, they have fulfilled their obligation, but at twenty amot (approximately thirty feet) or higher it must be relit.
A menorah that is exceedingly tall may rest level with the floor so that its lights will be at the appropriate height. Out of respect for a mitzvah-article, a flat tray may be placed as a barrier between the menorah and the ground. According to most poskim, it is sufficient for the menorah itself to be in the ten tefachim range, even if its lamps are higher. To keep the lit menorah out of the reach of a child, a higher placement is certainly permissible. When there is a safety concern, there is room to be lenient and place the entire menorah above ten tefachim.
When more than one menorah is placed in an identical location, a heker (distinguishing feature) is necessary, such as each individual lighting their own candelabra, placed in a way that allows the viewer to easily observe how many lights each menorah contains. It should not appear as one menorah.
Rav Yosef Yeshaya Braun, shlita, member of the Badatz of Crown Heights. Day-To-Day Halachic Guide, reprinted from crownheightsconnect.com
