When adding on a new room, it's important to plan for your electrical needs. Consider how many outlets you want, and where. Typically, a room is required to have a wall outlet every six feet, though your local code may vary. Think about wiring for your light fixtures: will you have one fixture in the center, recessed lights in the corners, or both? Don't forget a light for the closet, too. You'll also need to decide on the location of phone jacks and T-V cable. If the room is a shop, upgraded circuits may be necessary, depending on what type of equipment you'll be operating. For a home office, you might want a separate fax/modem line, or I-S-D-N. If the room you're adding is very large, or your electrical system is already 'maxed out', you might even need a panel or service upgrade. Meet with a qualified electrician in advance, and discuss all the details, while the walls are still open. Trying to install wiring once the walls are closed up becomes much more difficult and expensive.