How to test power output of 30 amp

[Damdifino]

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?

[time2roll]

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.

[Big_Katuna]

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

[Damdifino]

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.

[wa8yxm]

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).

[dougrainer]

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

[2oldman]

He's gone.

[Big_Katuna]

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.

[BFL13]

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.

[Lwiddis]

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

[road-runner]

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.

[wa8yxm]

There are 3 ways to do it. Easy, Easier and not so easy.

To test POLARITY and voltage get a 15-30 amp adapter and a THREE LIGHT outlet tester. You can find the first in the RV section of some Super stores (IE Wal-Mart) or any RV store and most campground stores the 2nd in the ELectrial of many stores (CW included) and most hardwares.

Plug the 3LT into the adapter and the adapter in. Two green (on most of 'em) means wired right. RED means Wrong. (Legend in printed on the 3LT in case it is different)

Then to check voltage plug in a Kill-A-Watt or measure (If the probs reach) slot to slot. and short slot to hole. (120/120 note that the 2nd test is optional)

Option 2

Plug in a portable Surge Protector like the Progressive Industries PT-30C that does all the tests for you Now easier than that it does not get.
NOTE if your RV is a 50 amp use the proper dogbone and the PT-50C

Or go with the hardwired version.. Again easier than that it DOES NOT GET


FInally the not so easy (But still easy) way.

How to wire a TT-30

This shows a photo of the TT-30 outlet

Neutral to ground should be zero volts
Hot to neutral 120 volts
Hot to ground 120 volts


Happy measuring (NOTE 115 to 125 is ok, 110 is marginal over 125 is not good either).

[time2roll]

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?

First look and see if it is a NEMA 10-30 connector. No good.



If you see a NEMA TT-30 then start testing.



http://www.myrv.us/electric/Pg/30amp_Service.htm

[Old-Biscuit]

Hot to Neutral..120V
Hot to Ground...120V
Neutral to Ground....ZERO

[Old-Biscuit]

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