Low Voltage - Heat Wave

[Lynnmor]

You might want to check your voltage if you are here in the east. My area dipped to 103 volts, that I observed, and it may have been lower. In a campground, with heavy loads, it is probably lower. I contacted the electric company and they said nothing can be done.

As some of you know, voltage below 104 can damage an air conditioner. And no, there is nothing on the news about the problem.

[Cummins12V98]

Low voltage has not been a concern using my 50A AutoFormer on the last three 5 RV's. Installed into my electric cord reel compartment. No worries about theft.

[CA_Traveler]

pnichols wrote:
I'm curious. If one has a 30A RV, but pays for a 50A RV site and then uses a 50A-to-30A adapter on the 50A pedestal receptacle to power their rig ... do they still run the risk of experiencing 30A low voltage service on high usage days?

Larger wire with less voltage loss is used for a 50A pedestal so you are more likely to have higher voltage with a 30A rig.

But there is always a risk. In 14 years with a 50A rig I've had low voltage on 50A one time running 3 A/Cs. It was a older CG, very hot day, all sites full and A/Cs running. Every 2 sites had a common hookup area, rigs parked in opposite directions, one site had a 30A pedestal and one had a 50A pedestal. It was in CA wine country so we bore the burden and went wine tasting. :B

[Ralph_Cramden]

Lynnmor wrote:

pnichols wrote:
I'm curious. If one has a 30A RV, but pays for a 50A RV site and then uses a 50A-to-30A adapter on the 50A pedestal receptacle to power their rig ... do they still run the risk of experiencing 30A low voltage service on high usage days?

Of course. It is possible that the 50 amp site might have less voltage drop if the wire size is larger, but you have no way of knowing that till you try both the 30 and 50 sites under load.

I started this thread to point out a significant problem. If the voltage is too low coming into the campground it can only get worse at the connection.

And it usually does get worse.

Typically its going to be wired thus.



I doubt anyone is going to go through the expense to run dedicated circuits to each pedestal for 50, 30, and 20, not that it would even matter.

I know of a PA state park that has a 30 amp pedestal between every two sites with 2 30 amp receptacles in each pedestal. The way its wired one recptacle is off the black leg, the other the red, and it alternates that way around the loop. It depends what leg youre on when the place is crowded. One receptacle can be 99 volts while the other is 137 in the same pedestal. I think they have a neutral issue going on.

Instead or replacing the 30+ yr old wiring, or remodeling 5 1960s era shower houses/restrooms, they spent the money upgrading 10 sites to FHU. They're also building a new shower house for their 8 rental cabins, which required about a mile and a half of sewer and water line. Talk about having your priorities in order

[Lynnmor]

pnichols wrote:
I'm curious. If one has a 30A RV, but pays for a 50A RV site and then uses a 50A-to-30A adapter on the 50A pedestal receptacle to power their rig ... do they still run the risk of experiencing 30A low voltage service on high usage days?

Of course. It is possible that the 50 amp site might have less voltage drop if the wire size is larger, but you have no way of knowing that till you try both the 30 and 50 sites under load.

I started this thread to point out a significant problem. If the voltage is too low coming into the campground it can only get worse at the connection.

[pianotuna]

Phil,

I have used an autoformer on several 50 amp shore power supplies. My breakout box has two 20 amp breakers on one leg and a 30 amp breaker on the other leg. Occasionally I have tripped the 30 amp breaker.

[pnichols]

I'm curious. If one has a 30A RV, but pays for a 50A RV site and then uses a 50A-to-30A adapter on the 50A pedestal receptacle to power their rig ... do they still run the risk of experiencing 30A low voltage service on high usage days?

[SoundGuy]

pianotuna wrote:
My comfort zone is 107 and up, so the current ems units are useless to me.

SoundGuy wrote:
Your choice, but clearly Progressive Industries' engineers who have selected 104 vac as their low voltage threshold would disagree. Choices, choices - whom to believe? :W

myredracer wrote:
You might start with reading the RV AC manufacturer's min. requirements. I've seen one of them specify. min. 105.

I'd have to check my documentation but as I recall my Dometic A/C specifies 103.5 vac so Progressive's 104 vac low voltage threshold meets that requirement. Regardless, by purchasing my Progressive EMS I've obviously chosen to put my trust in their engineering rather than someone's internet opinion. 😉

myredracer wrote:
As well, a static min. voltage reading isn't always the whole picture because when an AC starts up and draws 5-6 times running current, voltage can drop out of sight and lead to damage to the motor windings over time.

Absolutely, but with an LRA of +/- 60 amps on compressor start up specifying a low voltage threshold of 107 vac instead of 104 vac isn't going to make any difference at all. When I tested both the Coleman Mach III+ and later the Dometic I currently have with an EU2000i source voltage from the genset momentarily dropped to half :E but the genset recovered almost instantly and did not shut down due to overload. Obviously I had to remove the EMS in order to do this but it did work reliably until ambient temps rose into the 90s. That was before I knew anything about the Micro-Air Easy Start so if I were to do this again I'd invest in an even more capable EU2200i and install an Easy Start on the A/C.

[CA_Traveler]

X2 Plus it's not clear what tolerance A/Cs have for low voltage which is so common in CGs. Years ago 2 of us actually measured A/C amps as the voltage was lower. Defying all wisdom the amps when down as the voltage dropped.

Motor theory teaches us lower voltage requires more amps for a given HP. Who says an RV A/C uses the same HP with lower voltage?

myredracer wrote:

SoundGuy wrote:

pianotuna wrote:
My comfort zone is 107 and up, so the current ems units are useless to me.

Your choice, but clearly Progressive Industries' engineers who have selected 104 vac as their low voltage threshold would disagree. Choices, choices - whom to believe? :W

You might start with reading the RV AC manufacturer's min. requirements. I've seen one of them specify. min. 105.

As well, a static min. voltage reading isn't always the whole picture because when an AC starts up and draws 5-6 times running current, voltage can drop out of sight and lead to damage to the motor windings over time.

[myredracer]

SoundGuy wrote:

pianotuna wrote:
My comfort zone is 107 and up, so the current ems units are useless to me.

Your choice, but clearly Progressive Industries' engineers who have selected 104 vac as their low voltage threshold would disagree. Choices, choices - whom to believe? :W

You might start with reading the RV AC manufacturer's min. requirements. I've seen one of them specify. min. 105.

As well, a static min. voltage reading isn't always the whole picture because when an AC starts up and draws 5-6 times running current, voltage can drop out of sight and lead to damage to the motor windings over time.

[SoundGuy]

pianotuna wrote:
My comfort zone is 107 and up, so the current ems units are useless to me.

Your choice, but clearly Progressive Industries' engineers who have selected 104 vac as their low voltage threshold would disagree. Choices, choices - whom to believe? :W

[pianotuna]

My comfort zone is 107 and up, so the current ems units are useless to me.

[SoundGuy]

myredracer wrote:
During peak demands of the summer and high AC use, voltage is just gonna go down. Guaranteed. Reducing voltage drop would be an extremely expensive proposition and will never happen.

That's not entirely true any longer. Here in S Ontario Hydro 1 along with the local hydro operators have been pouring considerable sums into upgrading facilities to help avoid this voltage sag issue. It wasn't all that long ago that even here in suburbia we could see significant voltage sag under conditions like we've been experiencing here in the east for the last week. Today incoming source voltage to the house is ~ 123 vac with minimal load and when I just turned on the trailer A/C my Progressive EMS showed me pulling ~ 14 amps yet incoming voltage to the trailer only dropped to 118 vac. In this heat virtually every house in the neighbourhood, every house & every business in the city will be running A/C so yes, the situation has gotten better in some heavily served areas. :B We travel though with our camper so I still expect to see low voltage situations, ergo the reason I protect the trailer with a Progressive EMS that will disconnect if the voltage drops too low.

[myredracer]

Lwiddis wrote:
“they said nothing can be done.”

Yes it can fixed. “They” just don’t want to spend the money. To heck with your RV damage.

Voltage can be as low as 100V and still be within the ANSI, NEMA & NEC min. requirements therefore the poco or a CG won't do anything. Some explanation of voltage tolerance boundary and ANSI C84.1 is here.

Older CGs can be much more susceptible to low voltage due to the way they were wired and due to the min. NEC requirements in effect at the time. An autoformer is a good "tool" to have for CGs but not much you can do at your house. Low voltage can cause expensive damage to RV components (esp. AC units) and cause some appliances to significantly underperform. A permanently mounted LED voltmeter inside and an EMS unit are also good to have so you can monitor voltage and have power automatically cut off below a certain level.

You can't blame CGs for low voltage. The majority of them simply built to the min. requirements of the NEC in effect at the time they were built. Utility co. voltage can drop in high demand situations like heat waves. The NEC allows a certain % of voltage drop between the poco service and point of utilization. During peak demands of the summer and high AC use, voltage is just gonna go down. Guaranteed. Reducing voltage drop would be an extremely expensive proposition and will never happen.

All the 50 amp RVs these days with their higher demands also contribute to low voltage issues.

Knowing that low voltage is a common issue when camping in the summertime is your first line of defense. Things you can do include getting an autoformer, choosing a CG built after 2005 (or one that has upgraded their electrical), choosing a CG that originally built above. min. code requirements, choosing a site closest to a pad-mounted transformer in a CG, use a 50 to 30 amp adapter (if you have a 30 amp RV) and minimizing your load in your RV.

We're currently in a CG in Bend Or, and after being here a week so far, the voltage has been pretty steady at around 115-117. There's still a few nice sites left here, so come on down!!

[pianotuna]

I've used the Sola Basic at 97 volts. It boosted voltage to 107. The boost points are 110, 100, and 90. Buck is at 135. If I had sufficient knowledge and skill I'd bump the boost points to 114, 104 and 94.

For the 97 volts, the shore power 15 amp breaker did pop after about 30 minutes. I reset it and added the hybrid inverter charger to the mix. That allowed me to cool the RV down, drawing energy from the battery bank and solar panels. I did limit input amps to 12 (post pop).