I need to install a sub-panel in a shed. Total run distance from main panel to sub-panel is 80 ft and includes three 90 degree turns. Burial distance will be 18". I'm thinking to install a 60-amp main breaker in the sub-panel and running #6-3 THWN in 1-1/4" PVC conduit. I hesitate using direct buried cable as it seems a bit more vulnerable (but I'm no expert). I will be driving an 8' ground rod. A worst case inventory of expected loads is about 30-amps (1500 watt heater, 300 watts in lighting, 12.5-amp table saw, other?). This gives me a bit of room to grow. Am I doing anything stupid?
Well, I would not say you're doing anything stupid. You have some very good questions.
- If you did decide to direct bury the wire the minimum depth for direct burial is 24", not 18".
- At least three #6 ( black, red, white) and one #10 insulated ground ( green coating).
- Anything <= 60amps just requires a #10 insulated ground with green coating.
Second, Consider voltage drop:
- Load: 30 Amps @ 240V Single Phase.
- Length of run: 80 feet
- Wire Size: #6 Copper
- Voltage: 240V
- Voltage Drop: .81 %
- Voltage At End of Circuit: 238.05
That is less than 3% which the NEC recommends for a feeder. Very Good !
Note: I would hesitate to install the ground rod if you have a in-ground pool in line of the transformer.
Correction: This being a feeder would require a grounding electrode!
because of the number of ckts you want, you need 60 amps minimum to your shed see article 225.. burial depth is 18 or 24 inches depending. see table 300.5. wire size for UF, six is only good for 55A. with pipe and #6 thhn, 65A, see table 310.15B16. here in WA you need TWO count'em TWO ground rods, (NEC may or may not say one will do, since i live in WA i dont care what it says, i have to install two). separate the grounds from the neuts. ground can be bare or insulated. you are not going to a moble home. sorry, i just looked at the posting date. you're already done. bye!