I have this old, small house, lived here for 30 years. Before my time, electrical service was upgraded a couple of times, apparently. There is currently 100A service to a circuit breaker box. Box contains 16 circuit breaker slots, two or which are labeled "do not install breaker here". There are no sub panels or fuses anywhere. The house has never been remodeled nor had the overall circuitry upgraded other than what I've already described. I'd like to get at least one additional circuit to the kitchen. These old places were never designed for microwaves, electric teakettles and all those modern appliances, so basically there is just one 20A circuit to the kitchen receptacles. I looked in the breaker box and find there is one open slot for a new breaker. But, when I look at the existing use of the box I see there is one buss for both ground and neutral. And it's pretty darn small. All terminal screws are in use, and in fact a couple of screws on the buss are hosting two wires - two bare ground wires on one buss slot, two white neutrals on another. I asked an electrical contractor about an upgrade to the box but that quickly outstripped my budget. I need to consider an alternative. First question - is it safe to have a single buss for both ground and neutral? I guess it was OK at one time but how about in today's world? Second question - is it OK that a couple of 20A circuits share buss terminals as long as ground is with ground, and neutral is with neutral? Third question - if all this OK, would it be OK to double up the neutral and ground of a new circuit with those of an existing circuit, as long as both circuits are the same amperage and approximate use? I was thinking the new kitchen 20a circuit could share ground and neutral buss terminals with the existing kitchen circuit since both are used only intermittently and for small appliances. The fridge is in a different room and is plugged into a different circuit than either the existing kitchen receptacle circuit or the proposed new circuit.