With older homes, there is often quite a bit of work that has been added to, or changed, over the years. This often shows up as wires spliced in the fuse box, or double wires under the screws.
I do try to find out what the wires are for; besides wanting to identify them on the panel schedule, quite often these wires are for things (like the furnace) that need to have their own circuit.
There's another matter that also needs to be looked into as well....the number of circuits vs. the appliances present. For example, a home with an electric range, water heater, clothes dryer- yet only one 220 circuit. Such an arrangement is clearly dangerous, and some additional circuits will have to be installed.
Likewise, if the box is full of #14 wire with 30 amp fuses, you'll probably need to split up some circuits.
If the house is full of three-prong receptacles, on an ungrounded system, I'll want to get that fixed- usually by using a GFI breaker.
In other words, for me there is much more to a service change than just replacing the fuse box. Simply replacing the box, while leaving the rest alone, assures that the customer will be calling you ("the junk breaker you put in keeps tripping")- and continues an unsafe situation.
If someone objects to my pricing, well, they're free to look around. I really don't want something bad to happen, that I was in a perfect position to prevent.
