Electrical problem

This can happen on a 30 feed. You are sharing power with the pedestal in the next spot.

When this happened to me I was plugged into the 30A plug.
The Motorhome next to me had only 80 volts and I had 160 coming into my rig. The one with the higher load will have the lower voltage.
The voltage will depend on the load on that phase.

happycamper002 wrote:
........
Others will not agree but the luxury of having a 240 volt that would run several appliances at the same time is an overkill in an RV........

Not an overkill in the south and southwest when temps are running 100+ with heat index even higher and you need two A/Cs to keep the RV even reasonably cool. Add in Microwave and other 120 vac current drawing appliances and you can't do that on 30 amp.

newlee wrote:
This can happen on a 30 feed. You are sharing power with the pedestal in the next spot.

When this happened to me I was plugged into the 30A plug.
The Motorhome next to me had only 80 volts and I had 160 coming into my rig. The one with the higher load will have the lower voltage.
The voltage will depend on the load on that phase.

The only way you can get a 160 vac to neutral is when you tap into an industrial 3 phase 440v 120/208 source that is common in industrial plant.Even with 160 v would indicate a faulty transformer from the utility company. Power supply for residential or any occupancy designed for human habitation which include RV (in North America) are normally supplied with 120/240vac. We are talking about losing the neutral which is not indicated in the problem you experienced. The standard 30A rv plugs only carry one hot and one neutral-so where did you get the other hot leg?
I am a retired electrical engineer and used to design power distribution systems for a living for almost three decades.

BB_TX wrote:

happycamper002 wrote:
........
Others will not agree but the luxury of having a 240 volt that would run several appliances at the same time is an overkill in an RV........

Not an overkill in the south and southwest when temps are running 100+ with heat index even higher and you need two A/Cs to keep the RV even reasonably cool. Add in Microwave and other 120 vac current drawing appliances and you can't do that on 30 amp.

I live in the high desert in Southern Ca and we get 110 F too.I have my 28 ft Class A that I wired with two AC. They are wired so they work alternately to avoid overloading the system. Worked for me for over twenty years with the 30A supply.

Ok, Electrical 240/120 volt 101
50 amp service is sometimes called 240 volt, the thing is that NOTHING in your RV actually uses 240 volt save perhaps an Intelletec EMS They all use 120 volt.

So why do we get 240 volt.. well we divide it in two, that's the neutral's job

The reasons for this are techinical and I'll post 'em down the page but the 240 volts is divided. now if your loads are PERFECTLY balanced (not possible or more accurtally, probility down less than 1 percent Then the neutral carries no current and if it's open, nobody will notice, But if your loads are NOT balanced (99+percent chance) then the line with the greater load will see reduced voltage, the line with the lesser higher.. Had a "limited" neutral in my house once and when the A/C kicked in the voltages went crazy, with one dropping to around 80 and the other topping 150. (I had meters on the line).

This may have damaged your motor home's electronics.


The technical stuff

Imagine a water system consisting of two pumps and some hydraulic motors as follows

One pump feeds fluid (water in this caee) into a pipe, this pipe feeds water,via a valve, to a turbine,, Return water from the turbine is fed to another pipe, with a "T" on the end (more on the other side of the T in a sec) that feeds back to the water storage tank.

The other side of this T feeds water on to a 2nd turbine, also via a valve, and from there to a suction pump, and back to the storage tank.

Now both pumps are capable of exactly the same flow, Both turbines also, IF all the valves are open..

If both valves are open, one pump is pushing say 10 GPM, the other is sucking 10 GPM and no water flows in the "neutral pipe" back to the tank.

But close a valve (just one) and suddenly the "neutral" is either supplying 10 GPM or Returning it (Depending on the valve)

Now.. Add a 2nd and 3rd and 10th Turbine (With control valve) to each "Leg"

You now have a very good description of how your RV is wired.

But what happens if the Neutral pipe gets clogged? Well, with the one side having it's valve closed, Tremendous pressure is built up at the break, (higher voltages on one side) and very little watter flows in the open side due to all this back pressure.

Now that is a bit differnet, but the idea is the same

How to deal with this in the future

A Progressive Industries HW-50C will check for open neutral and advise you if same exists, It will also block power from your RV if said exists so you do not suffer damage. Air Conditioner Compressors are EXPENSIVE.

happycamper002 wrote:

newlee wrote:
This can happen on a 30 feed. You are sharing power with the pedestal in the next spot.

When this happened to me I was plugged into the 30A plug.
The Motorhome next to me had only 80 volts and I had 160 coming into my rig. The one with the higher load will have the lower voltage.
The voltage will depend on the load on that phase.

The only way you can get a 160 vac to neutral is when you tap into an industrial 3 phase 440v 120/208 source that is common in industrial plant.Even with 160 v would indicate a faulty transformer from the utility company. Power supply for residential or any occupancy designed for human habitation which include RV (in North America) are normally supplied with 120/240vac. We are talking about losing the neutral which is not indicated in the problem you experienced. The standard 30A rv plugs only carry one hot and one neutral-so where did you get the other hot leg?
I am a retired electrical engineer and used to design power distribution systems for a living for almost three decades.

You can get higher than 120V if you lose the neutral between the power source and a pair of 30A sites, one using L1 and the other on L2. The thing is, there isn't a complete circuit until there is something plugged into each site and then they are in series with 240V. In this case the other hot leg is you get is from the other site's hot leg, through their RV to the neutral you share.

wnjj wrote:

happycamper002 wrote:

newlee wrote:
This can happen on a 30 feed. You are sharing power with the pedestal in the next spot.

When this happened to me I was plugged into the 30A plug.
The Motorhome next to me had only 80 volts and I had 160 coming into my rig. The one with the higher load will have the lower voltage.
The voltage will depend on the load on that phase.

The only way you can get a 160 vac to neutral is when you tap into an industrial 3 phase 440v 120/208 source that is common in industrial plant.Even with 160 v would indicate a faulty transformer from the utility company. Power supply for residential or any occupancy designed for human habitation which include RV (in North America) are normally supplied with 120/240vac. We are talking about losing the neutral which is not indicated in the problem you experienced. The standard 30A rv plugs only carry one hot and one neutral-so where did you get the other hot leg?
I am a retired electrical engineer and used to design power distribution systems for a living for almost three decades.

You can get higher than 120V if you lose the neutral between the power source and a pair of 30A sites, one using L1 and the other on L2. The thing is, there isn't a complete circuit until there is something plugged into each site and then they are in series with 240V. In this case the other hot leg is you get is from the other site's hot leg, through their RV to the neutral you share.

This is the correct answer. If the neutral is open, or even has a high resistance connection between the point the two circuits connect to the common neutral and the power source.

Happens to stick built houses also. Had one house that was popping light bulbs like crazy. After testing turned out to be a failure in the utilities transformer internal neutral connection.

Dave

happycamper002 wrote:

newlee wrote:
This can happen on a 30 feed. You are sharing power with the pedestal in the next spot.

When this happened to me I was plugged into the 30A plug.
The Motorhome next to me had only 80 volts and I had 160 coming into my rig. The one with the higher load will have the lower voltage.
The voltage will depend on the load on that phase.

The only way you can get a 160 vac to neutral is when you tap into an industrial 3 phase 440v 120/208 source that is common in industrial plant.Even with 160 v would indicate a faulty transformer from the utility company. Power supply for residential or any occupancy designed for human habitation which include RV (in North America) are normally supplied with 120/240vac. We are talking about losing the neutral which is not indicated in the problem you experienced. The standard 30A rv plugs only carry one hot and one neutral-so where did you get the other hot leg?
I am a retired electrical engineer and used to design power distribution systems for a living for almost three decades.

Kind of scary that an electrical engineer does not understand this.

happycamper002 wrote:
the luxury of having a 240 volt that would run several appliances at the same time is an overkill in an RV. Then again it's just me.

Yup. It's just you.

wa8yxm wrote:


A Progressive Industries HW-50C will check for open neutral and advise you if same exists, It will also block power from your RV if said exists so you do not suffer damage. Air Conditioner Compressors are EXPENSIVE.

Bingo