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Comments for What’s causing fluctuating line voltages in RV?

  • Greetings Gary,

    Voltage fluctuations are a natural result of many factors (i.e. Power Plants Generators and Distribution, , Local Distributions, Connections, Amp Loads, Wiring Sizes, Wire Type, etc). All play huge factors. Campgrounds are notorious for incorrectly sizing their loads and provide very little maintenance of their units once installed.

    There are standards for fluctuations. Here are but a couple:

    http://www.powerqualityworld.com/2011/09/voltage-fluctuations-flicker.html

    http://www.powerqualityworld.com/2011/04/ansi-c84-1-voltage-ratings-60-hertz.html

    Even generators are notorious for voltage fluctuations as they are mechanical devices and the RPM on the generator cannot be kept at an exact RPM turn ratio. Especially as new loads are introduced such as the start up of an A/C unit. Start and Run Capacitors are added to compensate for some of this surge affect.

    But the good news is that most devices are designed to operate within a “band” of ranges. An appliance rated at 120 Volts can operate usually anywhere from 105 to 128 volts.

    As for the inverter, it is a pure sine wave inverter and they are designed to take a range of input voltages and provide a constant out voltage that does not change. Having said that, it’s important to purchase a quality inverter if you want durability as they do take on a lot of heat.

    One item that all RVer’s should consider installing is a Power Monitoring System such as one offered by Progressive Industries. Low voltages, incorrect voltages, cross phasing, dropped neutrals, Lost Grounds, etc are but a few things that will cause your equipment damage. This system monitors this and will drop out power to your RV to prevent the damage in nanopseconds. It will allow you to investigate the problem and correct the problem before damage can occur. We have one on our RV and it has saved us a number of times. BTW…I have no affiliation with Progressive Products but I am a happy customer to date.

  • If the voltmeter is digital, and it most often fluctuates between the 2 same values, it could be that the actual voltage is between the 2 displayed values, and the meter just can’t decide which to display. You could double check with a plug-in analog meter and see if the needle fluctuates.

    My guess is that this is normal digital meter behavior and there really is not a problem.