OK, here you go:
- 3/4" Schedule 40 Rigid PVC conduit is good for (4) 6-gage THHN/THWN wire. Per Table C.10.
- for 60 amp sub-panel to that location, run (1) 6-gage white - neutral; (1) 6-gage black - hot; (1) 6-gage red - hot; and (1) 10-gage green - ground. Use stranded wire, it will be easier to pull. Some jurisdictions do not allow taping (color coding) a standard black 6 gage wire (ie - San Francisco). You should
use color coded for 6 gage and larger gage wires.
- The conduit should be buried minimum 18" Ideally
, it should be sealed and sitting on 6" of sand, so 24" total. Unless it runs under a concrete slab.
- Attach a pull string to the wires and pull out the feeder wires. Ideally, use a fish tape, but the pull line will be good. Make sure it is strong enough.
- I am not sure what type/size of service you have and where you live, so the amount of ground rods will vary. For instance, in San Francisco, it is (2) ground rods, 6' apart. In Marin County, it is (1).
- If you have a 200amp service, use #4 copper. If you have 100-150amp, then #6 copper. Bond to the ground/neutral bar (if it is combo meter/main/distribution) and run to ground rod (8' x 5/8" for most areas) and then water pipe. Or, some areas allow vice-versa and more ground rods. Rods need to be minimum 6' apart. One continuous run on the ground wire. Use either solid or stranded. Protect ground wire appropriately.
- Finally, match the 60amp breaker make/type to the panel you have. IE - Murray breaker to Murray panel. And, make sure you have the load allowance.
- PS - just read your grounding method. If it was me, I would ground/bond the main panel and run a ground wire through the conduit since you said you grounded the kitchen outlets to the main panel. However, a second ground rod, at the garage panel, is good. Oh ya, bond to the water pipe within 5' of the water pipe coming into the house from underground.