However, a significant amount of the decision rests on the cost to deploy - in particular the cost to supply a power connection, and the cost to feed fibre - which requires space in ducting going in the right direction, or new ducting.
That makes a lot of sense. I've now got examples of cabinets that literally have 30 houses connected to them in the middle of nowhere. The one cab I'm thinking of has had to have two sections of ducting added (I think about 120 meters) to get fibre to the cab.
When you say you've "now got examples of cabinets", do you mean just that these examples are viable? Or is there something else about them?
However, your comment about those cabinets being viable for BDUK isn't my understanding. We had advice from a lawyer who specialises in the subject and he said if more than two principle providers (e.g. the area had cable on a large proportion of properties) then it wasn't possible for a subsidy to be applied for.
Are you sure the lawyer is talking about cabinets, or areas?
Certainly the concept of being an NGA white area goes to a finer level of granularity than a cabinet's coverage area. As Mr Saffron posted, Warwickshire have coverage maps that appear to be based on postcodes (they're fascinating to zoom in on), and are asking the public to identify anomolies.
There, BDUK would certainly show the streets that have no Virgin presence as NGA white areas - and so be candidates for NGA subsidy.
But what does this mean when considered at a cabinet level?
My impression is that subsidising a cabinet is *not* an all-or-nothing affair. Rather the subsidy would apply to the proportion of customers that live in the white zones, but that the "bid winner" would have to use it's own money (and commercial criteria) for the remaining proportion.
Perhaps this is an issue that TBB can take up: What happens where a cabinet area has a mixture of NGA white & grey zones (or even black zones)?
After that, the decision then depends on who decides. If BT themselves would decide, I guess they get told the amount of subsidy available, and the decision will be based on whether the volume of subsidy available is enough to take the cabinet over the threshold into viability.
If the council decide, then I guess they just get told how much subsidy is required to make each cabinet viable. They then have to choose (on a subsidy-spent per person basis?) which cabinets get done, until their budget is used up.
I also don't think the council could pay for the sub-station to be upgrade. In that example, the area becomes viable for FTTP rather than FTTC. BT will not talk about FTTP.
Perhaps the council has other subtle ways to get the cost of supply spread over multiple parties (or years).
I guess you say that the area becomes viable for FTTP because that is unpowered equipment, right?
If so, I'd re-phrase that. I'd say that FTTP may become the only possible candidate, but it doesn't make it any more viable. Certainly the lack of FTTC makes FTTP-on-demand unlikely.
Another course is to just wait, until some other infrastructure change causes an upgrade to the electricity supply independently. Then the cabinet viability may swing the other way.