low amperage

[Jimdel41]

i was camping last week at an older camp ground in south louisiana and was having trouble with the breaker at the campground kicking off in the extreme heat of the day. this is the first and only time this has happened since i got the motorhome about 2 months ago. had an electrician check and he told me i was pulling 26 amps on a 30 amp system. i have a 04 pace arrow with the 30 amp shed system. i was running both air conditioners and this only happened around 3pm -6 pm in the evening . the coach units ran all night and all day until this time of evening. i had camped for 4 day in the same weather at a campground approx 15 miles from this campground with no problem. the electrician thought i had a problem with the coach. i got home plugged in to power at the house let both airs run at the same time of day and did not have a problem. i think the problem was low voltage at the campground. any thoughts from more experienced campers. thanks in advance.

[jzick]

Another good reason to always use an energy management system that will monitor electric. Low/fluctuating power can cause serious damage to AC units and other electrical stuff.

[myredracer]

Almost guarantee it was low voltage. If it gets down to 105 volts and less, that's not good. It's bad for some appliances and components and can cause damage. It's especially hard on AC units.

If it drops to 105V, you should "power down" and go on life support. Lights will be okay since running on 12V. Anything that has a resistive element only inside such as a coffee maker or toaster will still function but will take a lot longer to work. Power output (watts) varies as square of the voltage so at 105V a toaster would be putting out 76% of it's normal rating.

It's a good idea to have a power line voltage monitor like the inexpensive ones CW has. I bought a permanent LED monitor that recesses into a wall.

Is there anything you can do? Yes. There is something called a Franks autotransformer that will boost the voltage back up to the normal/nominal level automatically. Not cheap and they're heavy. ww.voltagebooster.com/ If you do decide to get one, understand that nothing is free in life and if you boost your voltage back to 120V, this device only makes it worse for everyone else in the campground. I do not advocate these for that reason and if you hear your fellow RVers cursing and screaming when you have one, you'll have to decide if you'll be able to sleep at night. Actually, if enough people had one in a cg, the entire system could be taken down.

Some campgrounds were just never designed to handle simultaneous heavy loads. Not sure what you can do in advance to find out and I guess the only thing is to read reviews. We were in one cg in Oregon 2 summers ago and the wiring was all strung up between the trees. Some of it was Romex which wouldn't even be legal. Our breaker box was swinging free from the wire attachment point 15' up the tree. No issues with ACs due to all the trees and mostly smaller trailers, but in the morning with lots of cooking appliances running it got down to almost 105 volts.

If you can, you are probably going to be better off the closer you are to the main source of power. If you can spot the incoming overhead high voltage wires and it comes in ear the office, get a site nearest to that.

[rexabbot]

You were running close to 30 amps with just the to A/Cs.
As soon as the frig or water pump or battery charger or whatever kicked in you would blow the breaker.

You can't run to A/C plus other stuff at the same time.

[FlyingDiver]

If the feed voltage was too low, the amperage pulled would have gone up. I agree with myredracer - the campground power was low.

Also, officially the lower limit is 108V. Nominal is 120V, +/- 10%, so 108-132 are the limits. Outside of that, you need to disconnect.

[flaggship1]

Myredracer - I am not familiar with a Franks Autoformer - I know the Hughes Autoformer and I have a PowerMaster Voltage Controller VC50.

I'm curious where you found your facts on a voltage controller or autoformer taking down the power grid for others. I think DWs hair dryer stands a better chance of doing that than the draw from the PM VC. Any info appreciated.

That said - if I read the OP correctly the breaker at the post was tripping. Are you saying a Voltage Controller / Autoformer would have prevented that? I'm ready to learn and appreciate your insight.

Also - glad I have mine mounted in my electric bay with my PI SP.
Steve

[FlyingDiver]

Originally Posted by flaggship1

I'm curious where you found your facts on a voltage controller or autoformer taking down the power grid for others. I think DWs hair dryer stands a better chance of doing that than the draw from the PM VC. Any info appreciated.

This is a common meme in the RVing community. The reasoning is that using an Autoformer to raise the voltage also raises the current draw. So if your demand is 20 amps at 120V (2400 watts), you'll be pulling 24amps if the pedestal voltage is 1000V (still 2400 watts). Plus a little for the inefficiency in the autoformer. A couple percent, maybe. If everyone (or a significant percentage) does that, then the amp draw on the park transformer goes up 10-20%, which drives the voltage down even further, which raises the amperage, etc, etc, until the transformer breakers kick off.

Could it happen? Sure. Is it likely? Depends on how bad the park power really is.

I don't have an autoformer, but I might get one in the future, but only for a specific case. My hookup at my dad's farm is low voltage, but only because it's undersized and a long ways from his main panel. Using an autoformer on that line isn't going to effect his house or anything else.

[YC1]

Was the breaker panel in the direct sun? If so put some shade over it. Not unusual to lose some capacity on a hot breaker panel.

[myredracer]

flagg,

Being an electrical engineer, that's my area of specialty... To simplify it, power into the autotransf. (watts = volts x amps) = power out. If you up the output voltage from an autotransformer, it's input current will go up when the input voltage falls below the nominal 120V. If you want your full 30 amps delivered at 120 volts and say the pedestal voltage is down to 110 volts, then the input current goes to 120/110 x 30A = 33 amps. It's just basic Ohm's law.

And as FlyingDiver says, if more fellow RVers started to hook up autotransformers, there would be a upwards spiral until the total cg amperage load exceeds the main campground breaker. Probably never happened, but is theoretically possible. This scenario is similar to a utility brownout leading to a blackout. (Utility companies use on-line voltage tap changers to maintain a nominal voltage.)


You'll find lots of discussions and info. in RV forums about the use of autotransformers, like here for example: Positive: Franks Autotransformers - Forest River Forums

[flaggship1]

I read much before spending the $650 to buy the PM VC50. I determined it was worth the investment and would do no harm to me or anyone else. I will do some more homework to better understand how the step up process is accomplished such that a 105 input voltage reading at the post - using this
pulls more out of the post than 105 being delved to the VC.

I thought I had it right in my mind but apparently it's acting like a vacuum cleaner sucking power from everyone. All I was trying to do was limit ware and tear on my appliances, etc., while getting the 50 amp VAC I was paying for, and no more - while allowing my EMS to shed and keep me going and PI SP to keep me safe from faulty posts.

Back to the text books. Threads can only go so far in educating. Thanks for sharing your expertise.

[FlyingDiver]

Your meter is showing 105V available at the pedestal, right? With the VC-50 in the circuit, what's the voltage? Should be 118V or so (website says max boost 12%). How does it get that extra voltage? By pulling extra current (amps) and converting that to volts. So if you're drawing (for example) 50 amps total (both legs), you're using 50 amps x 118V = 5900 watts. But the input is actually only 105V, so the draw from the pedestal is 5900 / 105 = 56 amps.

56 amps into the VC-50 (at 105V) gives you 50 amps out of the VC-50 (at 118V).

[flaggship1]

Originally Posted by FlyingDiver

Your meter is showing 105V available at the pedestal, right? With the VC-50 in the circuit, what's the voltage? Should be 118V or so (website says max boost 12%). How does it get that extra voltage? By pulling extra current (amps) and converting that to volts. So if you're drawing (for example) 50 amps total (both legs), you're using 50 amps x 118V = 5900 watts. But the input is actually only 105V, so the draw from the pedestal is 5900 / 105 = 56 amps.

56 amps into the VC-50 (at 105V) gives you 50 amps out of the VC-50 (at 118V).

Oops - that was hypothetical. On Edit - So the 50 amp breaker at the post let's me pull 56 amps without tripping? I'm going back tongue books. Unfortunately they are in the mh at the shop.

[FlyingDiver]

Originally Posted by flaggship1

Oops - that was hypothetical.

What part? The calculations are the same, just change the draw amp number to what you're actually using. The short answer is, if the VC-50 is doing 12% boost, then you're actually pulling 12% more amps than your inside EMS is showing.

["007"]

Welcome to irv2.
I would add for starters a Surge Protector if you have none at least it will protect your electronics in your coach from any surges up or down from campground power systems.