GFCI breaker problems in trailer

Either the breaker is faulty, or you wired it wrong. Check the documentation for the breaker to determine the correct wiring.

Typically you connect the ungrounded (hot), and grounded (neutral) branch circuit conductors to the appropriate breaker terminals. Then you connect the breakers grounded (neutral) pigtail to the neutral bus bar.

Uh-oh. Your voltage (hot to neutral) should not be 130V anywhere except a few countries where 127V is common.

Start by measuring across the two hot "legs" in your panel. This value should be 220-240V, tending toward the latter, e.g. 238V.

Now measure each leg to neutral, these should be very close to half that, and very close to each other, e.g. 118-120V.

If they are not, but the two values add up to the first number, you have a very dangerous condition called a "lost neutral": the two "hots" are good, so 240V machines are happy. But the "neutral" is floating, and voltage on each leg is going to vary all over the map as the loads change, e.g. 171V and 67V, which will cause your appliances to catch fire. If you have this, shut off the main breaker now and unplug everything 120V or 120/240 until you fix it for good.

In light of your dryer error, a more likely possibility is that you have lost a leg of "hot". In this case, all the 120V circuits on that leg will be out, while the ones on the other leg work fine. 240V-only appliances will not work. 120/240 appliance controls may work, but the heaters won't. This is not an emergency in the same way as a lost neutral.

You may be having this problem with your entire house, it may have only appeared first at the pool. I gather your dryer is not at poolside.

The answer for any kind of "lost" wire is to give the panel a thorough take-apart and inspection. Look for loose screws (prticularly on heavy-wire lugs), corroded or arced contacts on breakers, burnt busbar, etc.

If you have a smart meter, good chance the power company can turn it off remotely using their SCADA system with a phone call.

White to green: In a properly wired house to code, with the main breaker off, resistance between neutral and ground should be as close to zero as your meter can detect. Voltage should be zero obviously. However, if any circuit is on, all bets are off. Voltage may be somewhat more than zero (but not more than 6 volts), which will make it impossible to measure resistance.