- What size conduit should I use? (I was thinking 3/4")
Since you're pulling more than 2 wires through the conduit, you're only going to be able to fill the conduit to 40%. Since you didn't specifically mention what type of conduit you're using, I'll list all metallic and PVC conduit.
- 3/4" Intermediate Metal Conduit (IMC) @40% = 0.235 in.²
- 3/4" Rigid Metal Conduit (RMC) @40% = 0.220 in.²
- 3/4" Schedule 80 PVC @40% = 0.164 in.²
- 3/4" Schedule 40 PVC @40% = 0.203 in.²
I'll assume you're using THHN/THWN/THWN-2 conductors, so you'll need to know the area of these conductors in the various sizes.
- 12 AWG = 0.0133 in.²
- 8 AWG = 0.0366 in.²
To figure out if the conductors will fit, you just have to add them up.
3 #8 x 0.0366 in.² = 0.1098 in²
3 #12 x 0.0133 in.² = 0.0399 in.²
0.1098 in.² + 0.0399 in.² = 0.1497 in.²
You end up with a conductor fill value of 0.1497 in.², which means you'll be able to use 3/4" conduit no matter what type you choose.
NOTES: For a look at some of the tables where these numbers came from, see this answer.
- Can I snake all wires for the AC and outlet in one conduit (2 conductor 1 ground for ac [8awg] / 1 conductor 1 neutral 1 ground for outlet [12awg]) - not sure the fill on this size
No problem, see above.
- When I stub up, I need to wrap around the foundation a little bit; any issue going above a hose spigot?
Shouldn't be a problem.
- Am I crazy for using rigid metal conduit? A lot of people I know say just go 'as deep as I can' and use PVC. But that's against code and even though this won't be inspected I try to stick to code as much as possible
You can use metallic conduit if you want, but it will likely be cheaper to use PVC (even though you'll have to dig deeper).
I think you may be confusing PVC pipe (used for plumbing), and PVC conduit (used for electrical). There's no problem at all with using PVC conduit, unless there's a local amendment that restricts its use. However, you'll only have to bury metallic conduit 6" deep, whereas PVC will have to be 18" deep. So if you don't like digging, metallic conduit might be worth the extra cost.
Turn off all the breakers, try them one at a time and see when the voltage returns, this should help to locate the problem area. Once you have the area found, turn on all the breakers, except the breaker to that area, and check it again. Now with the problem breaker/breakers off, go through the devices and check if any have a bad wire. I would start with the switches that controls the outside light.
Best Answer
Is it practical? I guess the question is, "does lightning strike twice?"
One problem is with near misses. Lightning has so much voltage at biblical amperage, that it creates a voltage gradient across the ground. Earth at your remote outlet could be 20,000 volts hotter than your house. This is what kills animals; the voltage on their front feet is different enough than their back feet that a lethal current can flow through their chest.
Without a ground rod, you hope the PVC and THWN insulation is strong enough to survive a 20,000V differential. With a ground rod, you remove all doubt - you are grounding both ends of the ground wire. That means the ground wire will be participating in this voltage gradient (helping to arrest it also). This has the risk of burning out the ground wire and having this voltage arc internally to the hot and neutral.
So lightning is such a slippery customer that it's hard for me to call it "definitely good". There are outlier conditions in which it could make things worse, as I described. But it's the way to bet IMO.
Of course, since it's not a mandatory ground rod, it doesn't need to meet standards for mandatory ground rods like the 25 ohm impedance test.