Wearing a Gartel during Menorah lighting?

In Sefer Haminhagim (page 8) it says that "Chabad custom is to wear a gartel (after one is married) for Tefila and for certain Mitzvos". The Sefer Haminhagim goes on to say that it is unclear which Mitzvos we wear agartel for, and why some and not others".

Later, by the Mitzvah of Kidush Levanah and lighting the Menorah (page 59) it says that our custom is to wear agartel. Why only these two?

[Side note: The Sefer Haminhagim was written by Rabbi Groner. It's known that almost everything was told to him (or shown to him) by the Rebbe.]

One way to understand this can to find a connection between the above mentioned two Mitzvos. Both are done during (or near) nighttime.

The reason for wearing a gartel is to separate the head - the upper half of the body, from the lower parts. At night we need extra protection.

True, we need to go out there, but safeguards must be set!