Updating electrical service
Some panels seem to only have three wires coming into them.
This is either because the neutral and ground are connected together at a different point (eg: the meter or pole) and one wire is doing dual-duty as both neutral and ground, or in some rare occasions, the service has only one hot wire (110V only service).
It helps to have a small backhoe or something when installing your new electrical service but you can dig it by hand if it's not too far. This panel has a 200A main breaker to feed a 200A break panel in the cabin and also has a 200A breaker panel built in.
There are four wires involved with supplying the main panel with power.
The other two wires will usually be black, and are the "hot" wires.
In fact, one of the first utilities you'll want to get connected on your construction site is power.
We installed a temporary power meter in the ground near the power company transformer by our cabin (give the utility company a call and see where they want you to place it if you don't know).
Reference NEC 2008, Table 250-66 Part of installing a new electrical service is mounting a main power panel or power meter. Utility companies will typically require a working space in front of your power meter similar to what is shown below.
This allows service technicians or electricians to comfortably and safely work with your power meter and main service panel.
Three of them will come from the utility company, and a fourth (bare) wire comes from elsewhere.