Voltage Drop w/AC on

[gosland]

Hi All - I have a 30amp RV outlet at my house. It tested 122v going in and coming out of the outlet. When plugged into my camper, my outlets in the camper show 120v, when I turn on one of the AC's (all I can do w/30amp) my voltage in the camper drops to 117v. I know low voltage is not good, but how low is "low"? I have not tested it at a campsite with 50amp yet. Thanks

[mjammersc]

117V is fine. For a reference the Progressive Industries EMS Surge Protectors Low/High protection points are 104V & 132V. 110-125V will be what you will see most of the time.

[jcurtis934]

As mark said...fine...but sort of sounds like that outlet is wired using wire that is a tad small in size to me...or maybe just old and tired like me. John

[gosland]

The outlet is wired with 10/2, about 45' of wire from outlet to panel. It seems like the converter in the camper is dropping the voltage.

[BB_TX]

There will be some voltage drop in the wires. And some in the connections. Make sure all the screws in your wire connections are tight, at your source main breaker panel, your 30 amp outlet, your trailer breaker panel, etc.

117 v is fine for your trailer.

[mjammersc]

The main drop is coming from the long lines. The drop won't be seen until you pull the current for the AC. 45' of 10 AWG is ~1.4V at 15A and then you have the line to the trailer and probably 20-30' of 12 or 14 AWG in the trailer which 25' of 14 AWG is ~1.9V. Here is a link to a voltage drop calculator where you can see how the numbers work - it is a good thing to look at when you wire something and have a working knowledge of, especially if you ever do solar. http://www.calculator.net/voltage-drop-calculator.html

Also the converter in the trailer converts AC to DC for all the DC powered items (inverters go the opposite way) so that is independent of the AC power drop other than the inverter may also be pulling more AC power to charge your batteries and run DC items in the trailer too which just adds to the line loss.

[Art-n-Marge]

Case in point, isn't the AC voltage usually between 120v and 110v, plus or minus 5 so 125v to 105v should be about right before any mototized sruff (like a fan, A/C unit, microwave or power tool) incurs damage? That said, there is nothing wrong with 117v.