Electrical – What wire type & size for sub-panel in a shed

Per the calculator here[http://www.electrician2.com/calculators/vd_calculator.html], 150 feet at 100 amps on 10Ga copper would be 15.5% drop - not the least surprising given that 10Ga is 30 amps in normal use and that's a long run.

• 3AWG copper is 3.1% drop - not quite kosher, but pretty close.
• 2AWG copper gets it down to 2.4%
• 3AWG aluminum is 5% drop.
• Aluminum has to be 1/0 (0) gauge to get below 3% drop (2.5%).

1" schedule 40 Conduit is not adequate to run a service with any of the sizes that will actually carry that load. I'd suggest 2" schedule 80 so that you could run it on aluminum wires, since they will cost a good deal less than copper, even at the larger size, in general. Schedule 80 only costs a little more than schedule 40, and is thicker/more robust. Since you already have it, run the 1" conduit in the same trench and you can use it for network, telephone, intercom or the like.

In a quick look at my local prices from vendors that publish prices...(there are often better prices from other vendors, but the relationship between Cu & Al is less variable.)

• adequate 2Ga Cu $1.79/ft
• not quite adequate 3Ga Cu $1.39/ft
• overkill 2/0 Al $0.98/ft
• and adequate 1/0 Al $0.82/ft

If you buy a separate ground wire, and upsize the conduit to fit it, there's also a 4/0 4/0 2/0 aluminum wire (twisted together, but not jacketed) for $2.09/ft, or less than 3 individual 1/0 wires. A better supplier might have a similar product with all 4 wires at a similarly attractive price. Depending on insulation type, that will still fit in a 2" conduit (or need 2-1/2 for other insulation types.)

None of this assesses whether your service into the building will carry the additional load, either. You may need to upgrade that before proceeding.

Both compressors (moreso) and tablesaws are hard to start - and both benefit from being run as 240V loads if possible, since they'll draw less current that way.

Your 200 amp service can supply your 150 amp water heater. But will anything else in your house require power at the same time? Such as a microwave, room or house heater, room or house air conditioner, stove or oven? Have you considered using the 24 instead of the 36?