Indeed so.I think more information might help in this situation, I mean if the OP lives in a detached house with some distance between neighbours then it is unlikely that the second fuse ever served a neighbour
As I said when that suggestion was made early on, it's certainly a possibility, but there are some things which perhaps make that less likely. For example, those 'new' fuse holders certainly post-date DC supplies, so it's not clear why it would have been fitted - unless for the reason previously suggested (the person who did it had no 'blankers' in his van, and therefore used a fuse holder instead).My money is on it being an old Dc supply that has been converted and is now just two phases, given the age of the incoming cable and the cutout, and that the fuse holders have been changed.
Are you talking about two fuses fed from the same single phase? If so, is that just because they didn't have a fuse of high enough rating and/or they were concerned about the 'rating' of the fuse holder?... That being said, the village where I grew up has no mains gas, and so a lot of people relied on storage heaters. A lot of people have now a second cutout fuse, that is redundant, having once served all the off peak heating. ... the bigger houses around here were built like that, obviously too greater load for the one fuse, but not enough to warrant a three phase supply.
I presume that would only apply to very large properties. Certainly in the past, I've seen countless 'average-size' houses heated by storage heaters and virtually all (***) have had a single-phase installation with a single (80A or 100A) fuse.
[*** my house is unusually large and rural (no piped gas) and was once heated with storage heaters, but it it did (and still does) have 3-phase supply - but it's the only domestic installation I can recall having seen in which 3-phase supply was used for storage heaters ].
Kind Regards, John