139:8 It is a mitzvah to place the Chanukah candles at least three handbreadths above the ground, but less than 10 handbreadths. If the menorah is placed more than 10 handbreadths high, it is still valid, but if it is more than 20 cubits high (around 30 feet), then it is invalid. (If one placed his menorah below three handbreadths, it is valid after the fact – Mishnah Brurah 671:26.) This is because if it is above 20 cubits, it is out of the public’s line of sight. One who lives on an upper floor can put his candles near a window even though it is higher than 10 handbreadths from the ground, but if the window is more than 20 cubits from the public ground level, it is not in the line of sight of passersby. In such a case, it is better to place the menorah by the doorway.
139:9 The candles should be in a single row (straight, not circular – Rema 671:4) at equal height, not one higher and one lower. There should be a space (of a finger’s width – MB 671:18) between one candle and the next so that the flame of one candle does not draw near to its neighbor, making it like a torch. Wax candles should be spaced apart so that the heat doesn’t make the wax melt and ruin them. If a person filled a dish with oil, placed wicks around it and put a cover on it, then each wick is considered its own candle; if it was not covered, then it may not even be used as a single candle because it is like a torch. If a lamp has two or more openings, it may not be lit by two people, even on the first night of Chanukah, because then it will not be evident how many candles each one of them is lighting. (If one has no other options available, he may rely upon the lenient position and do this on the first night – Shaar HaTziyon 671:16.)