It seemed to me that the wiring between the transformer and the
lightfittings would radiate horribly. The length of the cable between
transformer
and lamps would depend on the building and who wired them up !

These low voltage lighting "transformers" do indeed radiate truly horrendous
amounts of hash right across the LF/MF range. There used to be some in our
kitchen but they very quickly got removed after I started LF listening. Even
LW/MW broadcast reception suffered noticeably, although the lead lengths on
the low voltage side of this installation were no more than about 1.5 - 2m.

On the other hand, the GE low-energy lamp in my lab is almost silent on
136kHz - which was something of a pleasant surprise.

73, Kevin G1HDQ