How can I measure amps available. My RV park tells me they supply 30 amp service. I doubt it very much as I don't have enough light to read by when the fridge cuts in. RV and appliances are 10 years old.
This is not the first time I've tried to have this question answered elsewhere.
Thanks for any assistance.

What is the distance from the parks electrical service panel and your connection and what size cable was used?

This sounds like a voltage drop problem not an amperage problem.

How can I measure amps available.You can tell by the number on the breaker. Voltage drop is another thing entirely.

About 150'

The simplest way is to buy an Ammeter and take a test reading on the incoming cable.

For a distance of 150' you are getting 231 Vac (+/-) at 30 amp. You could purchase a larger sized cable, using #6 AWG conductors ($$$$$$) to get the 10 volts back, personally not worth it.

Have the RV park test the circuit to prove they are supplying 30 amps at 240 volts. Or have them move your connection point to a different transformer.