I had an interesting variation on this situation (I've posted it here before). When my house plans were being formulated, my plumber, who was going to install the electric boiler and electric DHW, recommended 400A service. But, when the electric service was installed, only 200A was run (??, I don't know why, same GC). While the house was being built, one of the first things they did after enclosure, was to run the in-floor radiant heat (this was during the winter at temperatures as low as -20°). No problem, the workers kept warm enough, even though the window and door openings only had plywood over them. THEN, the GC realized his mistake and decided to upgrade to 400A which meant running a new line from the pole transformer to the meter (on a stand 150 feet away from the house), replacing the meter, and running a second 200A buried line to the house and installing a second load center. He said it was his mistake and would only charge me for the additional materials, but I'm not sure. My boiler can use up to 100A by itself (it's on a 120A circuit). Anyway, I still don't think the extra 200 was necessary but it's nice to have the second load center, the first one is full! Are your quotes for 200 or 300 Amps, or is that the difference?

Just weighing in from another obscure section of the country. Rural western Maine. My town does not HAVE a permit process for electrical work, so all the permit discussion is irrelevant. If you call the power company and ask them to come turn off the power so you can replace your breaker box, they will send someone out who will do so. However, if you ask for permission to cut the seal and pull it yourself, that will also be allowed, a note will be made and the meter reader will re-seal it next time he comes around. IF you choose to have the poco cut the power, the entire "inspection" process when you call for it to be reconnected consists of the poco guy himself checking to make sure that you have all the necessary grounds and a proper service disconnect. They do have some company-specific rules/preferences with regards to the installation of NEW services, but replacing/upgrading an existing one seldom meets with any more than this basic inspection. The biggest danger I can imagine in pulling the meter is not being electrocuted. As someone pointed out, it's 120/240. People survive getting shocked at that voltage every day (and yes, I know, some don't). However, a dead short on the poco side of the meter base would be nearly-unlimited current. My only fear of doing this has been based on that scenario. Perhaps the last guy who worked in there, the one who hooked up the meter base to begin with, screwed up somehow and the incoming wire isn't tightened down sufficiently, and during my removal of the meter, it will work its way out and hit either the side of the box or one of the other wires? Perhaps the meter base has been overloaded, the terminals got really hot, the insulator material that holds them in place has become brittle, and during my removal of the meter, one of them will break off and again hit either the side of the box or one of the other wires? I do it anyway, as I feel it's my risk to take, but I do believe this could happen. Re-energizing, what if whatever you replaced while the power was off happens to be defective from the factory? I always turn off the main breakers then do a continuity/resistance check of the LOAD side of the meter base (meter removed) to see if anything is shorted, but what if something weren't COMPLETELY shorted and just happened to break down when higher voltage (120/240 as opposed to the 3V from my meter) was applied? Again we're talking about nearly-unlimited current (10-20 thousand amps), rapidly-expanding air molecules (from the heat from the spark) and a nice refreshing shower in molten metal. Again, I do it anyway, but the risk is always in my mind, and I can picture it happening some day. I do have a concern with the original poster doing this work. I've said in here a billion times I think it's great when people REALIZE that they don't quite know something, and ask. I think asking all the right questions is just as good as knowing all the right answers. The original poster, however, seemed quite convinced that a 200A panel could just be thrown in place of a 125A panel, and didn't so much as ask about the size of the wires going up the mast (mast? wow, around here we just have SE stapled to the side of the building!) I make no negative judgment against those who "don't know", but those who "think they know, and are wrong" are dangerous.

Great! Thanks for your patience in reading all that detail. Thanks for your responses. Further: I will run a full size (4 AWG) NEUTRAL. What size GROUND should I run in the house to shed panel conduit... a green insulated 6 AWG stranded copper maybe? I will use a 70 AMP breaker in my house panel. Another person gave the same recommendation. Should I make the associated step-down for the main breaker in the shed panel from 100 AMPs to 70 AMPs or leave that as described? Regarding "install a ground system (2 rods typically)": My house was built in 2005 with one 8' ground rod wired into the main house panel by the electrician. Electric co-op employees stood on that single bar when they connected my meter to the power pole. Is the "2 rod" ground system new since 2005 or did everyone involved in energizing my house leave me with something that is dangerous, illegal, bad? Thanks again.

I thought about the conductor/resistance part. I dismissed it for a couple of reasons and I hope my logic was sound. Tell me if it is not. First, largest length of larger conductors is the drop or underground feed between the transformer and the home. The length of these are short compared to the conductors between the meter an the use point. The contribution is negligible. There are some homes that have a long way between the transformer and the home and maybe the OP has this situation. Second, the power loss in the drop or underground feed does not count because the meter is measuring power. In this light, the homeowner will save the power company some power by buying a larger service. The growth of power consumption in residential sites grew for so long ,and the bias to making bigger when replacing equipment is so strong, that increasing service size is almost a knee-jerk reaction. Will we ever see the point when someone needs to replace a rusted-out 200A main panel and meter and says, or the electrician says, don't need 200A, you could probably get away with a 125, but lets oversize and go with 150? Recently, I arranged a service size increase in my dad's home. I did not want to. He had 125 A service going back decades, but I think the 1959 original was smaller. The nominal 200A combo main panel/transfer switch that I chose had two choices for main breakers, 200 and 150A. Darn it! That forced a complete main service replacement. On the positive side, adding the remaining stuff did not add much to the overall cost of genset instalation. Ron, in your situation, if they are really bothersome, I'd be tempted to sign up for the energy savings program and then watch them scratch their heads after showing up. That kind of event might generate useful feedback to the sales part of the organization from their own field people (that is not getting trough from you). Once I got a call from a long distance telephone service provider asking me if I wanted to sign up. I thought for a second and said, go ahead. This was not too long after deregulation of that part of telephone service. At that moment, I was sitting at a university phone :-) The university had a system that went out and compared rates from two or three long distance services and put your call through the best way. I don't know what happened as a result of my saying yes to that caller. I am reasonably sure it is not what he expected. Was I being mean-spirited? I don't think so. I did benefit from a little amusement. I did not see my saying no and explaining likely being productive. If lucky, maybe I saved hundreds of other people on the university's exchange from nuisance calls and forced a productive change on their marketing end before they got too far into it.