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Old 11-29-2022, 04:58 PM   #1
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THOR #10956
Open neutral

Electrical question

50 amp service. Outlet and cord have been tested and are good. Running Hughes Watchdog EMS (hard wired) Flip on breaker, EMS does its test, rv powers up without issue. At some point later the EMS kicks off with an open neutral error message. ( could be 30 minutes or 6 hours). EMS will immediately reset and start the whole process over.

If I truly have an open neutral in the RV how could it be on/off , on/off? Whit would it error out, but immediately reset?

Iím leaning to think the problem might be the EMS. Itís only been installed for about 5 months, no issues until now.. Anybody every seen anything like this? Any help will be appreciated.

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Old 11-29-2022, 05:26 PM   #2
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Take the ATS apart and check every connection by removing, inspecting and properly reconnecting. Many have found loose connections there with wire nuts

Also check every main connection in the panels by physically torquing them

Torque preferably with the power off unless you have proper tools
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Old 11-29-2022, 08:02 PM   #3
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Quote:
Originally Posted by EVMIII View Post
Electrical question

50 amp service. Outlet and cord have been tested and are good. Running Hughes Watchdog EMS (hard wired) Flip on breaker, EMS does its test, rv powers up without issue. At some point later the EMS kicks off with an open neutral error message. ( could be 30 minutes or 6 hours). EMS will immediately reset and start the whole process over.

If I truly have an open neutral in the RV how could it be on/off , on/off? Whit would it error out, but immediately reset?

Iím leaning to think the problem might be the EMS. Itís only been installed for about 5 months, no issues until now.. Anybody every seen anything like this? Any help will be appreciated.

You have two possible issues:

An intermittent open neutral, or
A faulty EMS.

To answer your specific question. The intermittent open neutral can be due to a poor contact situation. The ATS mentioned above is a likely suspect but it can also be the SP cable or any of the connectors.
The connection starts out good until current flows through it, heats it up, makes the connection high resistance (open) which your EMS sees and shuts everything down. Once shut down, no current is flowing, the contact cools and becomes lower resistance (good) and the cycle starts again.
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Old 11-30-2022, 02:50 AM   #4
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First, you need to find and inspect all connections between the post and your Hughes. Including the inside of the Hughes for loose connections. Cable connectors, sockets, including the back side of the rigs power socket. I always carry DeOxit D5 contact spray. Keep all connector contacts oxide free. I suspect it maybe the connection in the back side of your Rigs power connector or inside the Hughes, but you cannot rule out the power cable.
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Old 11-30-2022, 03:08 PM   #5
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Don't rule out the post!

I had a similar problem with the post's neutral wire. The post would work most of the day until late the afternoon when the suppertime crowd began consuming power. In my case I only had a surge protector. All of a sudden, the power would begin pulsating. The ATS would be clicking loudly, lights flickering, microwave flashing, co2 alarm chirping, a plug-in voltmeter needle swinging. In the end before maintenance figured it out and fixed a bad burnt connection in the post it destroyed the ATS, converter and inverter.

I would follow the suggestions above first. Especially the ATS connections.
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Old 12-02-2022, 03:55 PM   #6
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Working isolating problem

Thanks for the help thus far, hereís where I am this morning.

RV is hooked to shore power (my house). Verified 120+ at plug on both lines, 0 on ground and neutral. Verified at cord plug also.

RV AC master breaker is turned off. Inverter/charger is On.

This is the readout from my hardwired watchdog EMS

Volts match the reading at the cord. Now to show my lack of electrical knowledge, what is this telling me? Why is everything coming off 1 line? Is measuring what is coming in the EMS or what is going out? If itís whatís coming out does this tell me the EMS is problem. Can someone smarter in the ways of electricity help me understand? Thanks again.
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Old 12-02-2022, 04:14 PM   #7
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Thanks for the help thus far, hereís where I am this morning.

RV is hooked to shore power (my house). Verified 120+ at plug on both lines, 0 on ground and neutral. Verified at cord plug also.

RV AC master breaker is turned off. Inverter/charger is On.

This is the readout from my hardwired watchdog EMS

Volts match the reading at the cord. Now to show my lack of electrical knowledge, what is this telling me? Why is everything coming off 1 line? Is measuring what is coming in the EMS or what is going out? If itís whatís coming out does this tell me the EMS is problem. Can someone smarter in the ways of electricity help me understand? Thanks again.
2.3 AC Amps is not a lot but the real question is:

If the "RV AC master breaker is turned off" (assuming you are talking about the double pole AC breaker in your Power center that removes SP from the breaker panel), why are you drawing ANY amps?

It could be the pass though coil on the EMS. It could be the SP activating coil on the ATS (if it has one) or, at 2.3 amps, I would say both. But that seems like a lot of current for 2 constant duty actuating coils.

But otherwise, it's perfectly normal for a single, or even multiple loads to pull from one hot leg. Other loads will pull from the other hot leg.
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Old 12-02-2022, 05:54 PM   #8
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2.3 AC Amps is not a lot but the real question is:

If the "RV AC master breaker is turned off" (assuming you are talking about the double pole AC breaker in your Power center that removes SP from the breaker panel), why are you drawing ANY amps?

It could be the pass though coil on the EMS. It could be the SP activating coil on the ATS (if it has one) or, at 2.3 amps, I would say both. But that seems like a lot of current for 2 constant duty actuating coils.

But otherwise, it's perfectly normal for a single, or even multiple loads to pull from one hot leg. Other loads will pull from the other hot leg.
I wasnít clear. I have 50 amp coming in. The master AC breaker in the RV is turned off. I am trying to isolate the ďopen neutralĒ to isolate the problem to the watchdog or the inverter. A little more research has shown that my charger only uses line one and since itís the only thing running so those readings make sense. It ran all morning without issue, I have just turned on the main RV AC panel breaker but Iím not running anything to draw power. If it still doesnít error Iíll start trying one breaker at a time with draw to see if I can find the problem.
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Old 12-02-2022, 06:26 PM   #9
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I wasnít clear. I have 50 amp coming in. The master AC breaker in the RV is turned off. I am trying to isolate the ďopen neutralĒ to isolate the problem to the watchdog or the inverter. A little more research has shown that my charger only uses line one and since itís the only thing running so those readings make sense. It ran all morning without issue, I have just turned on the main RV AC panel breaker but Iím not running anything to draw power. If it still doesnít error Iíll start trying one breaker at a time with draw to see if I can find the problem.
You're still not clear:
The Inverter does not go through your EMS.
If the "master AC breaker in the RV" is turned off, nothing should go through your EMS.
Is your "charger" the converter? If so, how is is running if the "master AC breaker in the RV is turned off"?

That's not going to work. Your EMS senses an OPEN NEUTRAL on incoming power, not on loads.

The loads just create more current draw to aggravate the intermittent problem on the incoming lines. So no need to flip load breakers one at a time, turn them all on and then load the SP as much as you can to "find" the issue.
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Old 12-02-2022, 07:59 PM   #10
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As you can see, I know just enough to be dangerous (literally). This is my understanding of the power system in my rv since the solar and EMS were installed.

1. Power comes from my shed from a 50 amp plug. I have checked this plug with a multimeter and everything checks out at the plug.

2. I am using a new 50 amp cord. Plugged into my receptacle itís tests just like the plug.

3. From the plug it goes directly to my Watchdog EMS.

4. From the EMS it runs into my switch (AC/Generator)

5. From the switch to my Victron Energy Multiplus 3000 Watt 12 volt inverter and 120 amp battery charger.

6. From the Inverter it goes to the batteries (charger) and to the AC panel.

Got a bunch of other solar equipment in there that the do their things and eventually get back to the inverter to store in the batteries or use in the RV.

As I understand the EMS missing neutral error message that I received is indicating the system is not detecting a neutral on the line inside the rv to complete the circuit. Since it is only connected through the switch to the inverter that problem has to be from the inverter back to the plug.

The neutral wire from the watchdog isnít finding a neutral on the switch or more likely the inverter.

Does this make sense?

Thanks for the responses.
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Old 12-02-2022, 08:28 PM   #11
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Originally Posted by EVMIII View Post
As you can see, I know just enough to be dangerous (literally). This is my understanding of the power system in my rv since the solar and EMS were installed.

1. Power comes from my shed from a 50 amp plug. I have checked this plug with a multimeter and everything checks out at the plug.

2. I am using a new 50 amp cord. Plugged into my receptacle itís tests just like the plug.

3. From the plug it goes directly to my Watchdog EMS.

4. From the EMS it runs into my switch (AC/Generator)

5. From the switch to my Victron Energy Multiplus 3000 Watt 12 volt inverter and 120 amp battery charger.

6. From the Inverter it goes to the batteries (charger) and to the AC panel.

Got a bunch of other solar equipment in there that the do their things and eventually get back to the inverter to store in the batteries or use in the RV.

As I understand the EMS missing neutral error message that I received is indicating the system is not detecting a neutral on the line inside the rv to complete the circuit. Since it is only connected through the switch to the inverter that problem has to be from the inverter back to the plug.

The neutral wire from the watchdog isnít finding a neutral on the switch or more likely the inverter.

Does this make sense?

Thanks for the responses.
Well Bud, I didn't wire your Inverter/Charger but the way it should work is:

From the ATS The AC SP goes directly into the Power Center to the incoming Main AC Breaker pair.
The Main AC Breaker pair powers the AC buss and each of the individual AC breakers including a breaker for your Inverter/Charger. The AC loads are all downstream of their respective breakers including the Charger load.
The charger supplies the House batteries and DC loads through the house battery disconnect latching relay commonly known as the USE/STORE or Master Power switch.
When no SP or generator is available your Inverter/Charger switches to Inverter mode and powers the AC load center back through its respective breaker. The Main AC Power breaker pair are not even in the circuit at that point.

So you can see where the EMS is only concerned with incoming power and connections from the SP pole through the SP cable to the EMS. With your EMS before the ATS it is not even concerned with your ATS connections.
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Old 12-03-2022, 03:18 AM   #12
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Just a note of caution. An open neutral will still allow appliances to run. The return will be through the opposite hot. Even loads will keep the voltages even on each side. When the loads are not even the voltage will increase on one side and go down on the other. Yes anything plugged in that uses power, microwave, TV, converter, etc. will be affected. Voltage too high will shorten its life and cause failures within a year or less. Under voltage may also cause problems as well. You need your neutral to provide the return. I had, without knowing a loose neutral in my power reel and it took a while to fine it. I lost more than what I listed over six months. The converter was the first, TV second, microwave third, an AC unit fourth, etc..
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Old 12-03-2022, 11:34 AM   #13
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What are you calling the EMS? If it is the WatchDog that you clearly have at the pedestal and the WatchDog is issuing an "Open Neutral" error then the open neutral is most likely at the pedestal plug in the pedestal panel. These kinds of open neutrals can and usually are intermittent. I once had to have the campground change the socket in the pedestal to correct an open neutral problem. The campground owner was clueless as to how two phase power worked. Each leg of a 50 amp service is 180 degrees out of phase with each other. Voltage between either leg and the neutral is 120 volts but voltage between the legs is 240 volts. That is why an open neutral can cause serious damage to appliances in your RV and must be corrected.
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Old 12-03-2022, 02:10 PM   #14
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What are you calling the EMS? If it is the WatchDog that you clearly have at the pedestal and the WatchDog is issuing an "Open Neutral" error then the open neutral is most likely at the pedestal plug in the pedestal panel. These kinds of open neutrals can and usually are intermittent. I once had to have the campground change the socket in the pedestal to correct an open neutral problem. The campground owner was clueless as to how two phase power worked. Each leg of a 50 amp service is 180 degrees out of phase with each other. Voltage between either leg and the neutral is 120 volts but voltage between the legs is 240 volts. That is why an open neutral can cause serious damage to appliances in your RV and must be corrected.
I am referring to my watchdog as my EMS, but it is hardwired in my coach. It is the first thing my incoming power reaches (just as if it was connected to the pedestal). I have checked connections on watchdog and everything seems solid. As mentioned I have checked the cord and pedestal and they check ok. Due to the randomness of the errors code I guess I canít rule out sporadic burp in the outlet. I am going to a state park up the road next week to just try it out on a different pedestal to see if that makes a difference. Nothing I do in the rv seems to effect the error, ie run everything, nothing, or something in between. Itís been plugged in for 24 hours now without the error but nothing is different than before. I did shoot every line and connection with my temp gun and didnít find anything getting hot. If the issue continues at the other pedestal I will shift my attention to the watchdog. It has a replaceable card on the inside. Thanks for all the help.
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Old 12-03-2022, 06:10 PM   #15
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You noted you checked your pedestal connections. did you check all 4 terminations at the main? Or wherever the 240v 50-amp originates that feeds the pedestal
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Old 12-03-2022, 09:06 PM   #16
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Do you get the open neutral everywhere you go or just in one location where you plug in? Everywhere would indicate a shore cable problem, only in one location would be your supply receptacle.

As others have said it is not uncommon to have a loose or arcing neutral wire. I have a Ting device at home which is very for detecting power quality issues including open neutrals (which can also occur at the utility providers transformer). I haven't used a Ting in a motorhome. See https://www.tingfire.com/

My homeowner's insurance (State Farm) got me the Ting for free as a fire safety device. It measures the voltage at 30MHz to detect problems. For intermittent problems it is good to have a recording device which the Ting approximates (you can't actually view the recording but it will tell you the results).
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Old 12-04-2022, 12:41 AM   #17
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Do you get the open neutral everywhere you go or just in one location where you plug in? Everywhere would indicate a shore cable problem, only in one location would be your supply receptacle.

As others have said it is not uncommon to have a loose or arcing neutral wire. I have a Ting device at home which is very for detecting power quality issues including open neutrals (which can also occur at the utility providers transformer). I haven't used a Ting in a motorhome. See https://www.tingfire.com/

My homeowner's insurance (State Farm) got me the Ting for free as a fire safety device. It measures the voltage at 30MHz to detect problems. For intermittent problems it is good to have a recording device which the Ting approximates (you can't actually view the recording but it will tell you the results).


Iím heading up to a local State Park for a couple days next week to check that out. As mentioned I have checked my outlet and cord and they always test ok, but due to the randomness of the error anything is possible. I sincerely hope my outlet is the problem, that would be the least expensive alternative. Thanks for the response.
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Old 12-04-2022, 12:54 AM   #18
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You can check the cord by putting your multimeter in continuity mode using an audible sound to indicate continuity. Then connect to the neutral at each end (with the cord not connected to power) and bend the cord around. If you hear an interruption of the sound then you have a loose or broken wire. You could also borrow a cord from someone and see if it still triggers your broken neutral alarm. In your outlet you should be able to check the wiring terminations for tightness. I also have a Seek Thermal infrared camera adapter for my iPhone. I have used it to spot loose connections which typically get hot.
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