Having a small cabin dropped at deer camp and I’m wanting to run two 20amp 120v circuits. One will feed outlet for window unit a/c and additional outlet and other will supply outlets and lights. We have meter and main panel on pole which feeds couple other things at camp. What should I install for sub panel in my cabin?
This could be served by a multiwire branch circuit in the cabing - one leg for the AC receptacle, the other leg for the rest of the receptacles and the lights. This way all you need at the cabin is a disconnect, and you can run everything from the panel on the pole.
Assuming you're running conduit underground, I'd oversize the conduit so you'll have room to upgrade in the future.
I would run 240V here
Running a 4-wire feeder to the cabin means that you can put 120V loads on opposite legs of the feeder, which reduces the amount of current flowing by half compared to running a single 120V leg (3-wire feeder), and thus reduces the losses due to voltage drop and reduces the wire size needed as well.
Put in conduit, and a fat one at that
Since you are planning to run the feeder underground, you'll want to put it in conduit to provide maximum damage protection. I would use 2" Schedule 80 PVC with the top buried a minimum of 18" as per NEC burial requirements and prefabricated sweeps for bringing the conduit out of the ground -- this provides enough room for pretty much any sort of service someone wants at the cabin site in the future, and is relatively easy to install.
Inside this, I would pull 4 12AWG THWNs (hot, hot, neutral, ground) through for the feeders, as this is treated as a single multi-wire branch circuit with a disconnecting means, and bring the conduit and feeders to a non-fused, 60A A/C disconnect box (these are quite inexpensive) mounted on the outside of the house (you will need a 2" to 1" reducing fitting and 1" PVC nipple to attach the feeder conduit to the AC disconnect, BTW).
At the disconnect:
- The two hot wires land on the two "LINE" lugs in the A/C disconnect box.
- The feeder neutral is left floating free until the loads are wired
- And the feeder ground wire is terminated to the ground bar in the neutral
You will not need a grounding electrode (ground rod) here as per the exception to 250.32. The breaker in the pole panel should be a 20A, 2-pole, AFCI type breaker -- this will provide the necessary protection for the entire cabin.
Your branch circuit plans are fine
You'll want to run two 12/2s from the A/C disconnect box -- one will feed the lights and receptacles as a "home run", while the other will feed a dedicated single 5-20T receptacle for the HVAC equipment. Each hot exiting the disconnect will land on one of the LOAD screws, while the bare ground wires land on the ground bar, and the white neutral wires all get combined in a wirenut. Further wiring of the interior can be done using 12/2, as usual, or 12/3 if you wish to use switch loops; 4" square boxes with plaster rings or flat covers are recommended due to the generous space they provide for wiring compared to normal single gang boxes.
As to air conditioner selection
While Houston is a warm climate, it still can get somewhat cold down there (to around 32°F). Thus, I would recommend some means of heating be present in addition to the cooling capability. Luckily, Amana makes a wall-sleeve-mounted (through-the-wall) heat pump unit that comes close to the BTU you are after, the PBH092G12CB, that runs off 120V. It's not suitable for colder climates because it is very limited in its supplemental heat output (only 1.1kW) and its low ambient capabilities (down to 38°F), but in mild coastal Texas, it should suffice in providing cooling and relieving heating needs in all but the depths of winter down there. (Larger units require 240V power, which would require a subpanel at the cabin.)
Jon.. I agree with the comment above. If you go to Lowe's or Home Depot you can get a small circuit panel very reasonably priced.. You can also maybe get what's called a Dryer disconnect Panel.. which will handle the 2 - 20 amp 120 volt circuits you are running to the cabin. They can also handle, usually, a 30 amp load so if you want you can wire that panel with #10 wire for extra ampacity for something you may want to add in the future .