Zack wrote:
I just recently bought a house that was made in the 1950's. I would
like to add a hot tub to the house (220V). Protection to the house's
electrical system is provided by a fuse box - which is full. My
question is, how do I add a sub panel to the fuse box assuming that the
electrical system can handle the load? I am assuming that I branch the
wire directly off (in parallel) of where it comes into the fuse box.


What size main fuses are in your existing fuse box? This should tell
you what size service wires you have. (I will assume a standard 60A
Square D fuse box.)

Do you have an electric range? If not, the cartridge fuse pullout
labelled "RANGE" can be used to power your hot tub (with proper GFCI
protection, etc.) or used to power a small subpanel. If the RANGE
connections are already being used by a water heater, dryer, etc., you
are kind of out of luck unless your fuse box has feed thru lugs (lets
you tap in after the MAIN fuses).

A better solution is to replace the fuse box with a breaker panel -- it
doesn't have to be 200A. You need to run a load analysis to see how
much you need (I only needed about 85A when I ran the calculations, but
opted for a 150A panel instead of a 100A or 125A so I would have enough
capacity to add a big subpanel later for a workshop.)

Bob