Yup, upper left of the schematic shows the terminal strip and breakers. The breaker amperage is listed to the right on the schematic. This terminal strip is downstream from the main fuse (300 amp on schematic) to the inverter/charger and the batteries. There is a single 8 ga. black wire that is terminated on that terminal block. On the other side of that terminal strip/block/assembly there is a 10 ga. Red (Jacks), an 8ga black (lights,furnace-waterheater, fans,slide switch, detectors), and three 10ga Red (don't know what they are for).
If possible, measure DC voltage of the 8 ga black wires at the 40 Amp circuit breaker. You will have power on both sides of the circuit breaker if it is functioning. If it's tripped, you will only have power on the single wire side.
