30A/20A pedestal

kohldad wrote:
For some reason I'm drawing a blank though I could wire a complete house and have done so in the past.

Installing a 30A/20A pedestal with breakers at my daughter's house. I want to have full use of both outlets at the same time so when we have two campers they each have a plug. Purchased a pre-wired 30A/20A box which will only be about 15 feet from the meter combination box. I have room for two breakers in the box.

Thinking I should just install a double 30A breaker in the combination box, run 10-3 in buried conduit to he pedestal.

Problem I'm having is since I will be using each outlet separate, will the 10 ga neutral be sufficient or should the feed actually be #6 to have the neutral large enough to handle the return for 30a and 20a outlet combined?

you would actually need a 30/20amp breaker, since the outlet rating would be over

i would install dual 30's and use 10-3 with ground.

when running opposite phases, the neutral would only take the difference

so with a 30 amp one side and 20 amp on the other side the neutral would only be pulling 10 amps

when running opposite phases, the neutral would only take the difference

so with a 30 amp one side and 20 amp on the other side the neutral would only be pulling 10 amps

That is where my thinking was flawed.

I can get by with a double 30A in the combo box because the breaker only protects the run. The pedestal has a 30A and 20A breaker protecting the outlets.

Reason for a 20A plug is it is GFI and will be used for other things. Only a small truck camper will be using it, not a large RV with high loads so the 20A will be enough.

Thanks for the quick response.

Moved from technology corner

For conduit, you need four separate wires rather than 10/3 + G cable. The wires need to be rated for wet locations (which commonly available separate wires generally are). So you'll either need to run the conduit all the way to the main breaker box, or have a box midway at some convenient place to transition from the cable to the wires in conduit.

(I think the code doesn't technically forbid using cables in conduit, but it does impose some additional size and derating requirements. Regardless, underground wiring in conduit needs to be water rated, so ordinary romex is out of the question. Pulling individual stranded wires is also a lot easier than pulling multiconductor cable, especially as the cable usually has solid conductors.)

If your pedestal allows for it, and I suspect it probably would, I might consider installing a 50A dual breaker for the main in the house panel and, of course, running the appropriately sized wires for 50A. That way, should there be a desire at some point in the future to upgrade to a 50A pedestal, only the pedestal needs to be changed.

DrewE wrote:
For conduit, you need four separate wires rather than 10/3 + G cable. The wires need to be rated for wet locations (which commonly available separate wires generally are). So you'll either need to run the conduit all the way to the main breaker box, or have a box midway at some convenient place to transition from the cable to the wires in conduit.

(I think the code doesn't technically forbid using cables in conduit, but it does impose some additional size and derating requirements. Regardless, underground wiring in conduit needs to be water rated, so ordinary romex is out of the question. Pulling individual stranded wires is also a lot easier than pulling multiconductor cable, especially as the cable usually has solid conductors.)

If your pedestal allows for it, and I suspect it probably would, I might consider installing a 50A dual breaker for the main in the house panel and, of course, running the appropriately sized wires for 50A. That way, should there be a desire at some point in the future to upgrade to a 50A pedestal, only the pedestal needs to be changed.

This works as long as the pedestal has its own breakers for the 30amp and the 20amp.

#10 neutral is fine for 15' split phase service up to 30 amps.
Split phase neutral only carries the differential in current so 30a max.
Similar to the laundry connection using split phase on a duplex outlet.

john&bet wrote:

DrewE wrote:
For conduit, you need four separate wires rather than 10/3 + G cable. The wires need to be rated for wet locations (which commonly available separate wires generally are). So you'll either need to run the conduit all the way to the main breaker box, or have a box midway at some convenient place to transition from the cable to the wires in conduit.

(I think the code doesn't technically forbid using cables in conduit, but it does impose some additional size and derating requirements. Regardless, underground wiring in conduit needs to be water rated, so ordinary romex is out of the question. Pulling individual stranded wires is also a lot easier than pulling multiconductor cable, especially as the cable usually has solid conductors.)

If your pedestal allows for it, and I suspect it probably would, I might consider installing a 50A dual breaker for the main in the house panel and, of course, running the appropriately sized wires for 50A. That way, should there be a desire at some point in the future to upgrade to a 50A pedestal, only the pedestal needs to be changed.

This works as long as the pedestal has its own breakers for the 30amp and the 20amp.

The pedestal in question was mentioned as having breakers. That's still a good point to make; the receptacles must have overcurrent protection that is not in excess of their ratings.

If the pedestal box didn't have breakers, you'd presumably have to run two completely separate circuits (withotu a shared neutral), unless somehow you found or assembled a ganged 30A/20A breaker, since you don't want a 20A receptacle on a circuit allowing 30A.

Not too far down the road someone is going to buy a new camper and want a 50 amp plug.
I would over size the conduit.

Dusty

Just to clarify....when you say "double breaker", you need one like this that is two breakers with a common trip. This will use two spots in the panel and ensure that the circuits are out of phase so they can share a neutral. In this case you can use either 10/3 UF cable OR run 4 THHN conductors in 3/4" conduit, usually red and black for the hots, and a white for the neutral and green for the ground.



IF you are referring to the unit on the left ion the pic below as a double breaker, you MUST run separate neutrals for the 2 circuits since they will be on the same phase, and you will overload a shared neutral. Not a big deal, just add another white in the conduit.

Yep, full size double breaker so each leg is on separate phase. Have all the material at the house now and just need to dig a deep 10' ditch.

Thanks for all the help, I'm sure my install will pass an inspection if ever done.