I live in an older ranch, built in the 1930's. The previous owner put in a 100 amp main panel (modern circuit breakers). There is also an old fuse box/sub-panel. The only thing running off it is an electric hot water heater. It has two 30 amp old-style screw-in fuses in it. The main supply wire running to the older fuse box appears to run out toward the meter. It definitely does not run toward the main panel. A friend with some knowledge about electricity told me that in days gone by, electric water heaters were metered seperately and this is likely the reason for the different line and panel.
My questions: Is this an independent line that doesn't tax the load to the main panel? Can I take adavantage of this by putting in a seperate panel and increasing the amps available to the house, maybe put the water heater, washer, and dryer, which are all in the area, onto a separate panel and free up space/capacity on the existing panel for other uses? And, how would I tell for sure if the line is truly independent?