Thanks Ianh, Urban, 3 bed. As far as I could see, (under the stairs full of junk). One fuse is used for the supply -> Meter -> Fuse Box. The other two are looped in off the first one, but dont have any outfeed. What's the usual supply to the Service Head rated at then if you could possibly use 3 X 100A Supplies?
If I remember rightly, I think it was a Single phase supply, but it was boxed in. The first 100A fuse was used for the supply,to the house hold, I think the other two 100A fuses were looped across the infeed, but there was no visible outfeed. I was curious why three fuses?
I'll try to get a photo but not sure how to post it on here,or post a sketch!
Texas_Ranger hit the nail on the head there - this is the sort of installation that would have been put in where a property would require seperate meters for flats etc. It is strange to see two fuses looped off the main cut-out (service head) as it does seriously reduce the load you can supply.
With a single looped service, you could put two 60A fuses in and rely on the diversity etc to prevent an overload. With two loops, you would only be looking at 30A fuses - more than enough for a one bedroom flat though.
It is unlikely that a PoCo would allow two loops these days - one is still acceptable over here, but a second would require a three phase service head, and a phase each.
The 100A written on the side of the fuse carriers is the maximum rating of the assembly, not the fuse size. A cut-out like this would normally have a maximum fuse size of 80A, as they will allow the current to exceed 80A for a while. If you wanted a 100A service, you would need a three phase heavy-duty cut-out
With regard to the conductor colours, these should either be red (phase) and black (neutral) or brown (phase) and blue (neutral) - these tails don't meet either of the current requirements!
One other thing - removing the cable cover on a service head in the UK can be seen as a revenue protection issue!
This is on a par with removing the meter seals and should not be done unless you have something in writing from the PoCo / metering company. The penalties can be quite severe!
I'm assuming the covers were over the unpainted areas and these covers would have been installed to prevent access to the tails prior to the meter. They should have tamper-proof stickers over them to prevent the screws being removed.
Once you have finished any work, you might consider letting the PoCo know that it wasn't sealed in case they want to come and re-seal it.