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Captain Slow · 07-18-2019, 07:31 PM

What is this display telling the coach owner? What is the voltage referenced to?

Boilervol · 07-18-2019, 07:53 PM

That’s your incoming line voltage and the amp draw on each line. Those voltages are off. They should both be close to 120v

Boilervol · 07-18-2019, 08:03 PM

If that’s your actual incoming power you need to disconnect. Do you have A surge protector with ems

DrPhil · 07-18-2019, 08:05 PM

Since you have a new coach, and assuming you've not had such a reading before, there is likely a problem with the 50 amp pedestal plug of the campground. If you get this issue repeatedly with different pedestals, then you might have an issue within your transfer switch or within your cord reel. In either case, I wouldn't use it until someone takes a look.

ptw · 07-18-2019, 09:03 PM

Most likely, there is a bad neutral connection somewhere. 135 is too high and 103 is too low. You will damage your equipment at those voltages. With a bad neutral the voltages will change with the loading on each leg. So it may go higher or lower yet. I would unplug it right away! Try it someplace else to see if it is your coach or the pedestal as Dr. Phil mentioned.

spyderRV · 07-19-2019, 01:51 AM

If the neutral was loose wouldn't the side pulling 2 amps have the lower voltage?

Sbrownstein · 07-19-2019, 02:38 AM

Quote:

Originally Posted by spyderRV

If the neutral was loose wouldn't the side pulling 2 amps have the lower voltage?

Well, I really don't want to think about that but if the neutral were totally gone, both legs would be showing the same current...until the load seeing 135 volts blows up. However, you can't draw any current unless at least one load on each legs is energized.

Mental gymnastics aside, should be disconnected and figured out quickly.

vsheetz · 07-19-2019, 03:02 AM

Yep. Both power legs are represented. One us too low. The other too high. Disconnect from CG pedistal and operate from inverter and generator until resolved.

Stuart W · 07-19-2019, 04:38 AM

103 +135= 238. Almost 240 volts. This indicates a lost neutral. With a lost neutral condition the voltages are not being regulated to 120V. Unplug immediately!

ptw · 07-19-2019, 05:14 AM

Quote:

Originally Posted by spyderRV

If the neutral was loose wouldn't the side pulling 2 amps have the lower voltage?

If it was a bad neutral on the coach the current would be equal on both sides and the voltage would change with the impedance of the loads. Looks like it may be a bad neutral on the campground transformer. With a bad transformer neutral, the voltage would also be dependent on what your neighbors are pulling. Check with other people in the campground to see if they are having problems, but disconnect first.

Captain Slow · 07-19-2019, 11:09 AM

Excellent responses! Everyone is right-on with their comments about the defective neutral. When I noticed the high / low readings on the Power Control System Central Monitor Panel made by “Precision Circuits Inc” I immediately went into panic mode.

Prior to making contact with Precision I verified the voltage at the pedestal, transfer switch (down stream of hose reel connections) and the breaker distribution panel in the coach. All the Line to Neutral points were something like 118 VAC and 119VAC so I couldn’t understand why the monitor panel read 103 VAC and 135 VAC. Then, while working in the breaker panel taking voltage measurements I discovered a voltage of 18.7 VAC between Neutral to Ground. So I measured the L1 to Grnd and L2 to Grnd test points and found the same readings as shown on the display.

Then I started to trace the wiring to the display, thinking someone had transposed the “Neutral” and “Ground” connections on the back of the meter. When I was able to contact the Precision Circuits tech support they told me something that was not in their documentation anywhere. The voltages on the display are from Line to Ground voltage taps! No where in their documentation available online do they tell you where the display voltages are taken from! All of you who have responded (thanks for responding) and myself assumed the measurements were standard Line to Neutral measurements.

Yes there is a grounding issue which I have informed the campground owners so they can repair.

The purpose of this posting is to let everyone know exactly how to interpret the voltage readings on the display, because Precision Circuits, Inc for some reason has chosen not to tell the coach owners who have this system in their coach what their system monitors. Strange marketing approach.

Sbrownstein · 07-19-2019, 11:50 AM

That is pretty amazing. So the indicator will NEVER warn about a floating neutral and a floating neutral will start to blow stuff up. Nice.

The grounding problem you have is pretty much innocuous until the GFIs start to refuse to operate because of a higher than normal neutral to ground voltage.

Strange.

Captain Slow · 07-20-2019, 07:58 PM

I should have titled this posting something else. My purpose was to inform owners what the display was telling them.
Not Very many comments. I bet you could make some money by asking people if these voltages are referenced to Neutral or Ground and one in a thousand could give you the right answer.

ptw · 07-21-2019, 06:40 PM

Quote:

Originally Posted by Captain Slow

Not Very many comments. I bet you could make some money by asking people if these voltages are referenced to Neutral or Ground and one in a thousand could give you the right answer.

I am sure there are several people here that could answer that question.