Low voltage at campgrounds? I found the solution.

Electrical household appliances are rated for operation at 120 volts. Toasters, hair dryers, electric heaters, etc. are all designed for use at 120 volts and anything less will reduce their output. Check the label on your appliances to verify. A motor only can sometimes be rated at 110 or 115 volts.

The output of purely resistive devices like say a toaster, varies as the square of the voltage. If you had a 1500 watt toaster and the voltage got down to 105, the output would be 1148 watts (reduced to 77% of the rating). Some appliances will struggle to work and some will take longer, or both. Some appliances are very heat output sensitive like those plastic food wrap things that seal the plastic on one end from heat.

Standard voltage in Canada and the US is 120 volts and is the "nominal" voltage that power utility companies are supposed to provide under lightly loaded system conditions. They are required to comply with standard ANSI C-84.1 which specifies the maximum limits to be minus 13% and plus 6% of nominal voltage which means the lowest level can be 104 volts.

Pacific Gas & Electric on voltage tolerance boundary

Further, the electrical code (NEC or CEC) specifies a maximum voltage drop in a system from the point of supply to the point of utilization. It used to be 3% but I believe it has been raised to 5% overall. The very worst case scenario would be 5% less than 104 volts 0.95 x 104 = 99 volts. At that level, the electrical code has not been violated and the utility co. is in compliance.

Where things can get way off is in campgrounds, mobile home parks and multi-unit residential buildings. The electrical code allows for de-rating of feeder cables (to one area of a CG, ex.) and main services based on "diversity" factors. It goes something like this: The first 5 units are calculated at 100%, the next 10 at 75%, the next 10 at 50% and the remainder at 25%. The theory is that not everyone is running at 100%, 100% of the time. However, as we all know, in the height of the camping season, campgrounds can be packed to capacity. On top of that, there can be a LOT of AC units running in addition to other loads in an RV. As a result, the voltage in campgrounds can get quite low, and still not violate the NEC or CEC. It's not because the electrician screwed up or the CG owner cheaped-out. The code may have changed in recent years on the calculation method though, as I don't stay on top of this anymore.

One thing I don't know is when a CG has pedestals with both 30 and 50 amp receptacles, how the de-rating is calculated. I doubt they are all calculated based on 50A, but what if there was an occasion where there were a lot of 50 amp-ers in use?

The above code calculation method does not take autoformers into account and if there are a lot of them in use, the feeder or system voltage could be even worse.

Autoformers will result in increased input current. To make math simple and using a 30 amp service, say the autoformer adjusts the output to a constant 120 volts and the CG is down to 100 volts. If you are drawing 25 amps (at 120V), the input current would be 120/100 x 20 = 30 amps. Ignoring the losses in an autoformer, the input power equals the output power. If your AC is running, you turn on a toaster and have some other loads on and are drawing an even 30 amps after the autoformer at 120 volts, the input current would be 36 amps and the breaker in the pedestal would trip (or in your panel) if a that level long enough.

Autoformers don't "steal" power as such, but they do drive the CG voltage down because they are drawing more current at the low voltage than would otherwise happen and your neighbors will suffer somewhat - could be insignificant or not, depending on the quantity of autoformers in use. Theoretically speaking, if there were enough RV-ers in a CG using an autoformer, the CG main breaker would trip.

As far as damage to AC units go, I would read your AC unit's manual. I read a Coleman manual last year that said damage occurs at 105 volts and below. An info page from Airxcel (Coleman) says it's okay down to 103.5 volts. I'm sure all the brands vary a little. Duo-Therm is 103.

Personally, I think 105 volts is a good figure to shut down. I sure wouldn't go sightseeing for the day and leave the power on at 105. I also think the low voltage cutoff of 102 volts for the SurgeGuard is too low. Regardless, we don't worry about our AC. In 3 TTs in a row, we've never used our AC even once because it just doesn't get hot enough around here where we camp.

Cummins12V98 wrote:

samsontdog wrote:
I have never in over 10 years told that I could not use my Autoformer in a Park

You have never been to Thousand Trails Palm Springs then!

A few years ago someone convinced them that Autoformers or the like were causing their pedestals to go bad. The fact was their pedestals were ancient and were in need of replacement. I guess this last winter they had no problems with people using them. I built ours in and it works great and by doing so I don't have to lock it up as they are easily stolen.

Palm Springs has changed it tune and now allows them. As stated above old wives tale, if the autoformer has any effect on the park it is to smooth out power as at least everyone that uses one will pull more consistently.

There is no park that would care whether you used or did not use an autoformer. As mentioned above, the autoformer draws additional amps and turns them into volts. It WILL bring lower voltage to higher numbers at the expense of total amps available. This is usually not any kind of an issue as we generally don't max out our amps but it can be if you are trying to run A/C plus other accessories on a 30 amp circuit. So now if you had 30 amps available without this unit you might only only have 20-25 amps left over.

Pedestal to Hughes autoformer to PI to ATS. Works great.

I am really glad to see that there are not a lot of autoformer bashers out tonight.

Bill.Satellite wrote:
There is no park that would care whether you used or did not use an autoformer. As mentioned above, the autoformer draws additional amps and turns them into volts. It WILL bring lower voltage to higher numbers at the expense of total amps available. This is usually not any kind of an issue as we generally don't max out our amps but it can be if you are trying to run A/C plus other accessories on a 30 amp circuit. So now if you had 30 amps available without this unit you might only only have 20-25 amps left over.

Look at my post just above. I said they did not allow them. That is a fact! Now they do that is a fact also!

That's a good indication that you should never visit that park again as they simply do not understand the product they don't allow. Many don't allow you to use a combining device (plug one into a 20amp and one into a 30amp (or 2 30's) and provide the RV with 50amp-60amp) but the autoformer does not do this and does not add an excess strain to the RV parks electrical system. There would be exactly ZERO reason for any park anywhere to disallow the use of this device. It just keeps the RV parked in their site safe from the crappy service they are providing. If they are not providing the crappy service and there is good 110-120V service available then the autoformer would actually do NOTHING!

Gil, in the middle of everyone going round about who does and doesn't allow boost transformers, very nice write-up !

Low voltage at a campground is kind of like a brown out, where the power company doesn't have the capacity to supply all its customers. Rather than cut some of them completely off, they allow the voltage to fall, which reduces the current draw. If all the customers used autoformers to bring their voltage and current draw up, there would be a blackout. Seen this way, it makes sense to prohibit autoformers in campgrounds.

The need for extra power for air conditioning on sunny days suggests it is a good fit for solar energy. Anyone know of a campground that uses solar for its electricity?

Harvey51 wrote:
... snip:

The need for extra power for air conditioning on sunny days suggests it is a good fit for solar energy. Anyone know of a campground that uses solar for its electricity?

Solar is great for individual off grid or RV applications, but isn't generally practical / cost-effective for commercial use without goobermint subsidies. Thus the reason you don't see campgrounds with space devoted to solar farms, and probably won't.

Harvey51 wrote:

The need for extra power for air conditioning on sunny days suggests it is a good fit for solar energy. Anyone know of a campground that uses solar for its electricity?

Yes, Buttonwood in PA has solar but it isn't working out all that we'll for them.