Inspected 38 a year old home with fuse main panel. The panel had 5 block fuses and 2 rows of screw in fuses.
The block fuses were made up of 3- 30 Amps, 1- 40 amp and 1- 50 Amp.
The 50 Amp disconnected the screw in fuses when pulled out. The panel was rated for 150 Amps. What is the main service rating?
Thanks
Did you check the disconnect on the outside of the home by the meter, There should be a main breaker pull out. That should give you the rating. If the box is rated for 150A it is possible it is 150 or 125.
Check the disconnect on the outside of the home.
What size were the service conductors ?
Unknown from here. But those green fuses are, typically, 30 amp. And 30 amp on what is probably 12 gauge wire warrants referral, IMO.
FYI, looks like the top wire is missing a knockout from my picture. Sorry unrelated 
There was no disconnect on the outside. Cable clamps were missing, abandoned wiring, neutrals doubled up and some arching observed. However, I need some help in determining main service rating. In most cases there is one pull out that would have maybe 100 or 150 Amps fuses, but this was muliple to disconnect all power.
Thanks for your help.
Attached is another picture. The 50 amp fuse had barely legible stamped on casing indicating main and lights. So is 50 Amps main service rating?
That is similar to a split bus panel . That 50 amp pullout feeds the smaller branch circuits .
The Aluminum service conductors are plainly visible in the first two pictures. The size of these will determine the Amperage. I would be guessing 2/0 but I am not there.
As mentioned since there is no single main OCPD you would need to determine the size of the service entrance conductors to know the size of the service. This service has five service disconnected means instead of a single main.
If the SEC’s are rated for 150 amps and the panelboard is rated for 150 amps I would go with 150 amps. 
Your answer is in post #3. What is the size of the service wires. If they are 2/0 then you have 150 amp service. If they are 1/0 then you have 125 amp service.