How to test power output of 30 amp

Damdifino wrote:

dougrainer wrote:
He has another post about his AC just humming. So, he probably thinks he has a power problem. Doug

You're right. I am obviously not versed in these matters. Because my A/C struggles and fails to start up, I reasoned that one thing to check would be the output of my shore power.

Check voltage at the breaker in the RV panel during start up.

It could measure fine at the pole. You should measure inside as close to ac as you can..

dougrainer wrote:
He has another post about his AC just humming. So, he probably thinks he has a power problem. Doug

You're right. I am obviously not versed in these matters. Because my A/C struggles and fails to start up, I reasoned that one thing to check would be the output of my shore power.

To test POWER plug a volt meter in inside the RV. I have 3 of them

An Analog on one leg.. Another analog on the other leg and a Kill-a-Watt digital on the inverter line And a nice new inverter to power the inverter line in UPS mode (Instant transfer if shore power lost kind of like a 2,000 watt UPS for your (or in this case MY) computer's of which 3 are right sensitive. (the other 5 are internal battery backup up plus one more that defaults to power on so it's ok. NOTE two of the sensitive ones are DVR's one of each is a Digital TV converter.. The rest of 'em have keyboards and touch screens and/or mice. Yup. do a log of computing).

He has another post about his AC just humming. So, he probably thinks he has a power problem. Doug

He's gone.

Checking under no-low load doesn’t tell you much.

More important is what the voltage at your AC with the compressor running.

That’s easy to measure at the RV breaker inside the RV or even at the ac unit.

Damdifino wrote:
I want to test the power output of my 30 amp plug on my house to which I connect my RV. Which two of the three holes should I put the probes from a multimeter in?

Assuming you meant "voltage" and not "power", as above- stick the probes into "hot" and "neutral"--mostly to make sure it is "120" and not "240"

If you want to know about the "power", now you need to check the voltage in a 15a receptacle in the RV while something is on, like the microwave. That "loaded" voltage will be lower. How much lower? is the question. If you are on a long thin gauge wire extension, this can be a real problem.

Why am I a little nervous about OP testing his plug?

The prior answers have assumed you really want to test the no-load voltage of your outlet, and they are probably correct. If you really want to test the "power output", you need to have a load connected to the outlet, 30 amps for a thorough test, when you read the voltage. No-load voltage is an indirect indication the the outlet will probably provide power, and you can go ahead and assume it will provide its rated ~3,600 watts, but you have not tested for that.