This is true because the quad that is coming out has the 30 A tied together for 240v and the 15's are not — they are individual 15 A circuits.

BTW, there is no 110v in the USA. You can call it 115/230 or 120/240 depending on how you measure it on your service.

Correction, I uploaded the wrong picture for the 15 amp breaker
http://forums.pelicanparts.com/uploa...1560463213.jpg

This is like failing all my quizzes leading into the final exam :) With the world watching haha.

On the original breaker, the (2) 15A circuits are each on separate "hot" legs. If you install the 15A tandem breaker, the (2) 15A circuits will be powered from the same "hot" leg. You have to make sure that the (2) 15A circuits aren't sharing a neutral or you could potentially overload the neutral with 30A.

I don't follow the purpose of the tandem 15A breaker. What is going to be connected to it?

The existing breaker occupies 2 spaces and provides (1) 30A 240V circuit and (2) 15A 120V circuits. In order to supply a 240V circuit the breaker has to occupy 2 adjacent spaces in order to connect to both "hot" buss bars which alternate from space to space.

I would probably just use 1 pole of the existing 30A breaker for the 120V circuit to the trailer, as it's really 2 single pole breakers internally, they're just mechanically tied together.

One additional consideration is that this circuit should probably be on a GFCI seeing as it's outside and cord connected.

Many thanks to all for the guidance - job completed (mostly) today, took all of 1 hour with lots of checking and rechecking.

After I mounted and wired the RV 30 amp box I jumped into the panel

1. Powered down home stuff like TV, Internet, and computers
2. Turned of all individual breakers
3. Turned of the main breakers
4. Verified all wires were dead (of course the main feed wires were still hot)
5. Knock out the access plug at bottom of panel
6. Ran watertight whip to panel, mounted in knockout hole, and cut the excess wire leaving 6" extra to play with
7. Connected RV box wires neutral and ground to the panel bar (only 1 bar in panel - assuming that is correct - I see existing green, white, and bare wires attached)
7. Removed existing wires to existing breaker and remove breaker
8. Connected the 2 15 amp black wires from previous install into new 15 amp tandem and install into the panel
9. Routed old 220V wires to back of box, with wires nuts, tape, and label.
10. Attached new 30 amp black RV wire to the 30 amp breaker and install into panel

Check everything over, take my tools back to garage, check everything again. Energize the 125 main breakers, turn on individual breakers, check everything out, then finally turn on the 30 amp RV breaker.

Success!

http://forums.pelicanparts.com/uploa...1560729620.jpg
http://forums.pelicanparts.com/uploa...1560729620.jpg

Here is the RV 30 amp box. You can see I left the watertight whip a bit too long as it is pressing against the feed lines for the pool equipment that is buried. I will have to take a couple inches off the length to keep it separate. Next weekend...I don't have my "big ass RV extension cord" just yet, the trailer is currently fed with 15 amp power for lights and basics. I also dislike the breaker labeling on the panel, will replace all with stick on labels.

http://forums.pelicanparts.com/uploa...1560729620.jpg

Again thanks all for your guidance and support!