It's definitely a loose neutral. I'll go further to state that, in the last house I lived in where we had this problem, it turned out that the neutral was actually *GONE*, and everything was going through the ground wire, to the incoming water supply, through the pipes in the road, through the neighbor's ground wire, and through THEIR neutral wire! I had always noticed the lights randomly changing brightness when I visited that house before moving in, but never realized the true severity of the problem until the day the water district unhooked a pipe in the roadway and half of the stuff in the house "blew up".

Call an electrician. Now. Unless you know how to fix it, in which case, get to it, now.

Oh, and a personal peeve.

USA has 120 and 240. There is no 220. 220 is not a multiple of 120. 120 x 2 is NOT 220. If you insist that we have 220, then we need to have 110 also.

Thanks for the quick responses. I put a call into my local power company and they are going to send someone out as soon as possible. If need be, I will also call an electrician to fix any inside wiring issues, since the power company only handles the feed up to the breaker box. I'll post the outcome of the situation when it's all fixed.

Also, thanks (pharkus) for the correction on voltage terminology.

110/220 V was an older standard for residential single phase wiring.

Upgrade in power distribution and better standardization finally led to the adoption of 120/240 V as the nominal voltages, each with about a 10% tolerance.

208 V remains a common voltage derived from 3 phase service.

At least part of the 110 vs 120 was due to the varying use of Y and delta systems in the distribution network.

I have like 126/252v .. Called PowerCo. They came out and measured volts and put a load on it,, said that was within acceptable guidelines.

Said they had loaned power to a neighboring cities power company and upped the taps temporaryly to compensate for the extra load at the time. They have left it there for a few years now.

Not a real big deal here but causes some ratching noise on some tripp-lite line voltage regulated ups's and transformers at times.

Indeed. That goes along with the "nothing's perfect" theory. 120V is seldom, if ever, 120V.

I BELIEVE the current "standard" is 120/240. That doesn't mean it's always (or ever) accurately 120/240.

I'm not so bothered by 110/220. Either way, the higher number is twice the lower number, unless you're in some area where they've given you two of a three-phase service, in which case the higher is 1.732 times the lower.

Getting the wrong "standard" voltage is easy and forgivable - it only indicates that the poster never bothered to look it up. Who cares. Getting the wrong multiplier indicates that you don't understand how the voltages are derived, or that your brain has a permanently-loose neutral.

120/220 will never happen, nor will 110/210, 120/250, 120/230, or any of the other odd combinations I keep hearing.

Like I indicated, it's all, ultimately, meaningless - it's just a personal peeve of mine. In the grand scheme of things, it doesn't matter if I call it 107/251.

"120/220 will never happen, nor will 110/210, 120/250, 120/230, or any of the other odd combinations I keep hearing."

You are assuming all power is single phase.
Odd combinations occur in a number of places with 3-phase power.

120/208 V is a common one.
The 208 is phase to phase on a 3 phase system, and the 120 is from a buck transformer across the 208 V.

Add to that that many older workers have been used to 110/220, 115/230, and if they worked in commercial stuff all sorts of weird combos exist.

Line-to-line and line-to-neutral in 3 phase differ by a factor of sqrt(3).

Do a search on 'CEBEMA curve' for a very common 'quality' level for AC power.

Link to cbema curve

Here is a link that might be useful: cbema curve

I just noticed that the curve above is only the droop side.
Below is an article with both sides.

Here is a link that might be useful: Better CBEMA

Brickeeye
You are assuming all power is single phase.
Odd combinations occur in a number of places with 3-phase power.

Actually, brickeeye, I specifically acknowledged your example: Me
Either way, the higher number is twice the lower number, unless you're in some area where they've given you two of a three-phase service, in which case the higher is 1.732 times the lower.

And that's all I'm saying: The multipler is 2, or 1.732. I am not saying anything else, and please don't correct me on anything I never said. Me
nor will 110/210, 120/250, 120/230

All numbers I've heard, and all invalid, unless something is broken. Brickeyee
Add to that that many older workers have been used to 110/220, 115/230

Both of your examples comply with my assertion. 110x2=220. 115x2=230. Brickeeye
Line-to-line and line-to-neutral in 3 phase differ by a factor of sqrt(3).

sqrt(3) = 1.7320508075688772935274463415059 - or, for those of us who don't need that many digits, the 1.732 I stated above.

To follow up with my situation, I had the local power company come out, and they actually found some damage to the neutral line. They replaced all three lines a couple of days ago, and so far everything is stable. I even tried pulling a large load through the RV circuit (by turning on a space heater, microwave, TV, etc.), and the voltage reading only changed by a couple of volts, rather than 15 to 20 like it originally was.

Thanks again for the good advice.

Glad you got it fixed, and on the POCOs nickel to boot.

"Neutral Fault" is the problem. By the way my country supply is 230vac.

You have described the classical unbalanced load problem on a house transformer. The outside transformer has a center tapped 240 V winding. The center tap is grounded. The voltage from either end of the transformer winding to ground is 120V, but the voltage from one end of the winding to the other is 240 v.

Inside the house in the distribution box are two "hot' bars and one neutral bar. One end of the transformer bar is connected to one of the hot bars and the other end of the winding is attached to the other bar. The center tap is connected to the neutral bar.

Here's a peculiarity of the transformer. The total voltage across the transformer winding tends to be constant. If a heavy current draw in one half of the winding reduces voltage in that portion, the voltage in the second half of the winding will rise and tend to maintain the total voltage. Therefore, if half of the transformer falls by 10 volts, the other half will rise 10 volts.

That is why electricians try to "balance" the circuit loads so that on the average, the load on each half of the transformer is approximately equal. If an out-sized load, say a welder, hits, one leg of the transformer, enough to drop the voltage in its leg, the voltage in the other leg will rise.

Whats happening is the RV is connected to a single house circuit and at times draws an out-sized current especially if other loads in the house also appears on the same circuit. The solution is to split the load from the RV and connect to two circuits, one that draws from one bar in the distribution box and the other drawing from the other bar.