Community Forums

RJay · 07-28-2011, 03:36 PM

Several weeks ago I post about the electrical facilities upgrade going on at the RV park where I'm staying. Yesterday I found myself in a conversation with the person who is over-seeing the upgrade and found out some interesting information.

The work is to upgrade the remainder of the park to 50 amp service. The voltage of the main trunk lines is three phase 480 volts which is reduced to three phase 120/208 volts at each distribution transformer throughout the park. From there the 120/208 volt feeds are then run from the transformers to distribution boxes where alternating two live legs with a neutral and ground are run to new power pedestals at each site.

What's interesting about this is the voltage going into the RV from the pedestal is 120 volts between each live leg and neutral and 208 volts between each live leg, where customarily it would be 240 volts. The is not an issue for most of us but for the newer all electric coaches it may cause performance problems for heating water and possibly resistance heating since those appliances may require 240 volts. Some high end coaches that have 240 volt heating elements in their Hydro Hot systems will suffer reduced hot water recovery times because of the lower voltage. I don't know if some of these high end coaches that have three roof air conditioning units are run off 240 volt motors but that would be a concern.

I'm not suggesting that this is a trend at other parks but it just reinforces the practice to test the voltages at the power pedestal before we plug in.

doc · 07-29-2011, 02:55 PM

Another reason I own a Progressive Surge Portector.

Nuge · 07-29-2011, 03:19 PM

Might be useful to say where this is at for those without a meter or knowledge of how to use one...It would be just TERRIBLE to pay for camping and electrical service only to have your systems fried by insufficient voltage!! Would the CG be responsible??

RJay · 07-29-2011, 03:49 PM

Doc,
Don't be lulled into a sense of security because you have a surge guard. In this case I don't believe it will detect this situation. In looking at the specs for a EMS-HW50C which I have, it states “If 240 volts is detected when plugging into AC power, the EMS will NOT allow power to the RV” I believe what this is referring to is a line to neutral 240 volt condition, not a line to line condition. A 50 amp service is 120 volts line to neutral for each of two live legs and 240 volts line to line. The only place in the specs that talks about a line to line condition pertains to surge protection not to voltage detection. I have a call into Progressive Industries to clarify this.

AFChap · 07-29-2011, 04:21 PM

Interesting / frustrating how some park owners what to take shortcuts in providing electrical service. The bottom line is that they will NOT be providing what they claim they are.

I know of a military park what provides both sides of 50a service from the same phase, which results in 0 voltage between the two legs. Most users never know they are not getting what they paid for...

wa8yxm · 07-29-2011, 05:08 PM

Your volt meter is your friend.

RJay · 07-29-2011, 05:17 PM

The people who run this park are very nice and care about the people who stay here. I don't believe the owner's are even aware of the consequences of this situation because they are away on a three week vacation. I'm hoping this is just a situation where the wrong transformers were ordered.

brucerob · 07-29-2011, 06:33 PM

Without going into a lot of detail a 120/208 volt service is not a short cut. This is the voltage that is used in most commercial installations including schools, hospitals, restaurants, large stores, etc. There are advantages to using a 120/208 volt 3 phase system as opposed to a 120/240 volt 3 phase system, the main one being that the amperage can be balanced on all three lines of the 208 volt system. On a 240 volt 3 phase system one line will have a reading of approximately 200 volts between hot and neutral, therefore that line would be unusable in an RV and all the load would only be on the other two lines.
480 volts 3 phase is an industrial/commercial voltage, they are not taking the cheap way out but are doing it the proper way.
I don't know how this works with the RV surge suppressors but I suspect, as was mentioned, that they read the line(s) to neutral. I also suspect that most loads in an RV are 120 volts. If there is a 240 volt heater on 208 volts the heat output will be decreased by approximately 25%.

I hope my reply answers some questions, I meant to keep it short but when I get going.......sorry.

RJay · 07-29-2011, 07:05 PM

Quote:

Originally Posted by Nuge

Might be useful to say where this is at for those without a meter or knowledge of how to use one...It would be just TERRIBLE to pay for camping and electrical service only to have your systems fried by insufficient voltage!! Would the CG be responsible??

There is no reason to create a problem for the park because RV'ers are not exposed to any problems. The portion of the park undergoing construction is not open to the public. Secondly, the other half of the park which is taking reservations has perfectly fine electrical service.

FlyingDiver · 07-29-2011, 07:29 PM

Quote:

Originally Posted by brucerob

Without going into a lot of detail a 120/208 volt service is not a short cut. This is the voltage that is used in most commercial installations including schools, hospitals, restaurants, large stores, etc. There are advantages to using a 120/208 volt 3 phase system as opposed to a 120/240 volt 3 phase system, the main one being that the amperage can be balanced on all three lines of the 208 volt system. On a 240 volt 3 phase system one line will have a reading of approximately 200 volts between hot and neutral, therefore that line would be unusable in an RV and all the load would only be on the other two lines.
480 volts 3 phase is an industrial/commercial voltage, they are not taking the cheap way out but are doing it the proper way.
I don't know how this works with the RV surge suppressors but I suspect, as was mentioned, that they read the line(s) to neutral. I also suspect that most loads in an RV are 120 volts. If there is a 240 volt heater on 208 volts the heat output will be decreased by approximately 25%.

I hope my reply answers some questions, I meant to keep it short but when I get going.......sorry.

I believe that may be appropriate in situations where all loads are 120 or specifically designed for 3-phase. Residential systems (which RVs count as), are designed for 240v split phases (aka 120/240), not 3 phase, and can be damaged by that installation. Sounds like someone did a major screw up on this one.

joe

brucerob · 07-30-2011, 08:15 AM

There are a few houses that have 120/208 volt single phase systems and many apartments also. I researched and could only find one rv product that uses 240 volts, that was a heating appliance and would not be damaged by 208 volts.
I checked the power monitors from both Surge Guard and Progressive Industries along with the Autoformer from Hughes, they all appear to be monitoring the 120 volt circuits (L1 to N on 30 amps, L1 to N and L2 to N on 50 amps).
I do not see how an RV electrical system can be damaged by a 120/208 volt system. The manufacturers of the RV's and related appliances must be aware that their equipment might be connected to 120/208 volts. This is not an unusual voltage and has been around for many decades.
Hopefully a manufactures' rep or a power monitor manufactures' rep can set me straight. I would much rather connect my RV to a modern electrical system, be it 120/208 or 120/240 volts than a old system of dubious quality.

FlyingDiver · 07-30-2011, 08:27 AM

I have a Maytag residential dryer in my unit that expects true 240v.

I sent an email to Progressive Industries to get their take on how their EMS-HW50C would handle that kind of feed.

joe

Nuge · 07-30-2011, 08:31 AM

Quote:

Originally Posted by RJay

There is no reason to create a problem for the park because RV'ers are not exposed to any problems. The portion of the park undergoing construction is not open to the public. Secondly, the other half of the park which is taking reservations has perfectly fine electrical service.

I wasn't trying to "cause" a problem for the CG owners, but PREVENT a problem for the M/H owners... Isn't that who this site is about??

njs42 · 07-30-2011, 08:48 AM

Quote:

Originally Posted by Nuge

I wasn't trying to "cause" a problem for the CG owners, but PREVENT a problem for the M/H owners... Isn't that who this site is about??

Ease up there---you are both doing fine. I do not understand any of this---but it is interesting reading and learning and I can assure you from an outsiders view no offense has been meant by anyone IMHO-----

I have never heard of any thing like this so this is very educational---thanks to everyone for sharing.