I imagine the 28A listed for the dryer is an over-estimated UL number, but nevertheless, it's what's on the label.
An attached 2-car garage will be built as part of the addition, and those 500 square feet are included in the 3VA/sqft calculations since the garage will be lit, ringed with receptacles, and include a workshop area. A 12x12' shed will also be powered (mainly for lights, although it's also set up as a workshop) but I didn't include it in the calcs. This house has city water, so no water pump is needed.
As a matter of philosophy, when the emergency heat is running is really, really, not the time to find out that you actually need just a few more amps on that service.
Exactly my concern! The way I'm thinking now is that it'll cost the same to upgrade the panel 2 years down the road as it will to upgrade it at the onset of the project. But again, if it doesn't need upgraded, that's a lot of money that doesn't need to be spent.
The worst-case scenario is a very cold day with both furnaces on emergency heat while a roast is in the oven, clothes are in the dryer and the water heater is on. (EG, christmas eve!) It would only trip the main once... wouldn't be difficult to have a *bit* of power discipline until the service could be upgraded. And even that is assuming the main will trip with a 200A load; in reality, it should almost always handle more for a short period of time, but I know it's very bad practice to rely on that. Speaking of which... are slow-trip breakers legal for residential use? We use them occassionally for shipboard power to handle large inrushes, but that's a whole world removed...
[This message has been edited by SteveFehr (edited 03-20-2005).]