Re: Small Subpanel Replacement
Old thread, so I'm probably way too late to the party.
For the load you describe, 10/3 as a 30A/240V service would be plenty adequate. But if you ever want to run heavier power tools (like an air compressor) you might want to go with a little heavier service (8/3 as 40A/240V). An air compressor starting up when you're running some other power tool could cause the circuit breaker feeding the garage to trip.
Originally Posted by MyMilan
You might never need the extra capacity, but having it could be a selling point when you're ready to move on. And if you ever imagine using an industrial-sized welder, you'll probably want at least 60A service.
If it's more than a couple hundred cable-feet (one-way distance) from the main panel in the house, you might want to upsize your wire to prevent voltage drop. If the no-load voltage is 123V, putting 30A of load at the end of a 200-foot run of 10/3 will drag the voltage down to 111V.
Calculate voltage drop here: http://www.calculator.net/voltage-drop-calculator.html
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.