The "Meg" Build

Lt.Dan

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Alright, im doing testing. Here's what I've found so far.

The negative from my 48v battery is grounded to RV chassis. Im assuming this is happening through the 48v to 12v converter, because the output of the 12v side is grounded to a common ground screw on the frame.

The inverters do have continuity to the RV frame. Touching one of the screws on the inverter case to the frame confirms continuity.

There IS a neutral-ground bond when isolated from the grid! I confirmed this by doing the following;
While hooked into the grid via a 50 amp RV cord, I tested continuity between the neutral and ground right at the output of the inverters. Good continuity.
I unplugged the 50 am RV cord (forcing it to island), and I STILL have continuity between Ground and Neutral. Is the inverter bonding these itself??

edit: i also confirmed no AC voltage between battery and chassis on either positive or negative.
 

Lt.Dan

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Just found the inverter has continuity across GROUND INPUT and GROUND OUTPUT, as well as continuity between NEUTRAL INPUT and NEUTRAL OUTPUT on the inverters. There is also continuity between neutral and ground on both input and output, no matter what one.

I also shut off the main 50a breaker inside the RV Power Distributing box and checked for the same neutral- ground bond, and it was still good as well.

With the same main 50a breaker on or off, there is 52v AC between dirt and RV chassis, so that makes no difference.
 

Lt.Dan

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I Also just confirmed touching my stairs and the dirt results in a pretty good shock. No Bueno.

How come I've never noticed this before?? Lol

OMG IM A TERRIBLE PERSON, THIS EXPLAINS WHY MY DOG HAS BEEN HESITANT TO COME IN THE TRAILER FOR THE LAST WEEK OR TWO.
 
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GSXR1000

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I Also just confirmed touching my stairs and the dirt results in a pretty good shock. No Bueno.

How come I've never noticed this before?? Lol

OMG IM A TERRIBLE PERSON, THIS EXPLAINS WHY MY DOG HAS BEEN HESITANT TO COME IN THE TRAILER FOR THE LAST WEEK OR TWO.
I would not trust a high impedance meter for true bond continuity.

on each inverter tie the N-G and see if that solves it. I did light research and I don't believe your inverter have dynamic bonding
 

FilterGuy

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The negative from my 48v battery is grounded to RV chassis. Im assuming this is happening through the 48v to 12v converter, because the output of the 12v side is grounded to a common ground screw on the frame.
OK.... that is a new bit of data. I did not realize there was a DC-DC converter. From what you say it is a non-isolated converter. (Most of them are not isolated)
There IS a neutral-ground bond when isolated from the grid! I confirmed this by doing the following;
While hooked into the grid via a 50 amp RV cord, I tested continuity between the neutral and ground right at the output of the inverters. Good continuity.
I unplugged the 50 am RV cord (forcing it to island), and I STILL have continuity between Ground and Neutral. Is the inverter bonding these itself??
When the shore power is hooked up, the NG bond back at the house is in the circuit so I would expect continuity when plugged into shore power.

However, when not connected to shore power, I would have guessed there would be no N-G bond. How did you test continuity? Was the meter on volts or ohms? (I would not have tried an ohms measurement on a hot circuit, and I am not sure what the meter would do if there is voltage there. Back in the old days (when the Dead Sea just had a small cold), hooking an analog ohmmeter on a hot circuit would fry the ohmmeter every time)

i also confirmed no AC voltage between battery and chassis on either positive or negative.
This would be expected with the Negative bonded to chassis through the DC-DC converter.

Just found the inverter has continuity across GROUND INPUT and GROUND OUTPUT,
This is expected. I have never seen an inverter where Case, Ground-in, and Ground-out are not tied together.
as well as continuity between NEUTRAL INPUT and NEUTRAL OUTPUT on the inverters.
How was that confirmed? Was the inverter powered on?
I also shut off the main 50a breaker inside the RV Power Distributing box and checked for the same neutral- ground bond, and it was still good as well.
How did you check for the N-G bond?

With the same main 50a breaker on or off, there is 52v AC between dirt and RV chassis, so that makes no difference.
OK.... that is good to know. it tells us the problem is before the distribution box.
 

Lt.Dan

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OK.... that is a new bit of data. I did not realize there was a DC-DC converter. From what you say it is a non-isolated converter. (Most of them are not isolated)
Yes, sorry, its in my thread, but I understand it's hard to keep track of everybody's little details lol.

This is the converter im using. https://daygreen.com/collections/36...w-dc-dc-step-down-converter-voltage-regulator
When the shore power is hooked up, the NG bond back at the house is in the circuit so I would expect continuity when plugged into shore power.

However, when not connected to shore power, I would have guessed there would be no N-G bond. How did you test continuity? Was the meter on volts or ohms? (I would not have tried an ohms measurement on a hot circuit, and I am not sure what the meter would do if there is voltage there. Back in the old days (when the Dead Sea just had a small cold), hooking an analog ohmmeter on a hot circuit would fry the ohmmeter every time)
I tested with the meter on Ohms, and it showed 0 Ohms and beeps like there was continuity. I did not think to set it to volts. It did not adversely affect the the meter, and still measures volts and amps correctly.

How was that confirmed? Was the inverter powered on?
Again with the meter set to Ohms, and yes the power was on. All of my tests were done with the inverter power on.
How did you check for the N-G bond?
I checked for continuity between Neutral and Ground but based on how you are explaining it, I was doing it incorrectly. Should I do this with the DMM set to volts again?
OK.... that is good to know. it tells us the problem is before the distribution box.
Should I still disconnect the input from the transfer switch like requested earlier?
 

Lt.Dan

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Coincidentally I'm going on a trip this Thursday, so tomorrow I will remove the input at the transfer switch like requested, and add the N-G bond in the Power Distribution block.

When I return from my trip, I can resume my diagnostics...
 

12VoltInstalls

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THIS EXPLAINS WHY MY DOG HAS BEEN HESITANT TO COME IN THE TRAILER FOR THE LAST WEEK OR TWO.
That’s an interesting detail.

What changed two weeks ago?
With … main 50a breaker on or off, there is 52v AC between dirt and RV chassis, so that makes no difference.
Am I remembering right you have two inverters?
So… there’s possibly something crossed hot/neutral between the inverters and breaker… if not then you know the energizing of the neutral/ground occurs NOT in the house wiring.
I’d kill the inverters A, then B, and see if it drops to zero when one or the other is turned off. Then disconnect the 120 outs both hot and neutral one at a time and test. If steps to earth go to to zero then that’s a thing. Once all four (2 black/white pairs) are disconnected if you still have 52V you know it’s the inverters.

You can test a lot of things with a meter but ohms while hot and several other things either lie to you or blow the meter up. Disconnecting one at a time one wire at a time is an absolute binary.
 
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Lt.Dan

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That’s an interesting detail.

What changed two weeks ago?
I've been trying to figure that out myself, but I cant think of anything.
Am I remembering right you have two inverters?
So… there’s possibly something crossed hot/neutral between the inverters and breaker… if not then you know the energizing of the neutral/ground occurs NOT in the house wiring.
I’d kill the inverters A, then B, and see if it drops to zero when one or the other is turned off. Then disconnect the 120 outs both hot and neutral one at a time and test. If steps to earth go to to zero then that’s a thing. Once all four (2 black/white pairs) are disconnected if you still have 52V you know it’s the inverters.

You can test a lot of things with a meter but ohms while hot and several other things either lie to you or blow the meter up. Disconnecting one at a time one wire at a time is an absolute binary.
Yes, 2 inverters, but they are communicating with each other, so if I shut one off, then the other will fault out and shut down too.

I'll pull the output wires out of the inverter's and test. If the problem goes away, then I'll work my way towards the transfer switch.
 

Lt.Dan

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Victron equipment looks nicer and nicer every day... but for similar rated equipment, I'm going to be $8-10k (for just the inverters and SCC's!). I'm not even $10k into my whole setup, including 32x 280ah cells, BMS's, 2x LV6548, 36x solar panels, tools, wiring, equipment, etc. lol.
 

K8MEJ

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Victron equipment looks nicer and nicer every day... but for similar rated equipment, I'm going to be $8-10k (for just the inverters and SCC's!). I'm not even $10k into my whole setup, including 32x 280ah cells, BMS's, 2x LV6548, 36x solar panels, tools, wiring, equipment, etc. lol.

True, and you get what you pay for. The Victron gear is pricey, but it's nearly bullet proof. But time is also money. That said, I'm sure you can solve your issue with what you have. Hopefully it's not a fault inside one of the inverters again.
 

Lt.Dan

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I just disconnected the Grid Power Input to the transfer switch, so now it strictly goes to the input on the inverters.

No change.

I was about to add the Neutral/Ground bond, but I realized I'm still plugged in until tomorrow, so I have to wait. This is a pain.
 

Lt.Dan

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Would anybody think this wouldn't work? This isn't my picture, its just one I found on the interwebs, and I just added the little red line in Paint. So imagine the bottom inputs are Generator (INVERTER) on the left, and shore power on the right. If I bonded neutral and ground before the transfer switch, then whenever the Generator (INVERTER) has priority, it will bond the neutral/ground and passthrough to the breaker panel. But when on shore power, it will already be bonded and pass through like usual.

Can somebody tell me I'm wrong and dont get it? This seems like a much simpler and automated solution.
pd52-15-1000_2_500.jpg

EDIT: Nevermind, I remember now that when the inverter is in "Bypass" Mode, it will already be bonded as well, making a loop. Damn.

EDIT 2: I never thought to check or anything, but I wonder if the factory Onan 5500 had a neutral/ground bond already. I'm assuming it had to, or else it would have the same problems I'm having now.
 
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FilterGuy

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Is this a picture of the inside of your transfer switch? It does not seem so because the case and background look different than the other pictures. Furthermore, this only shows 120V for the grid power in and I thought you had 240V for the shore power plug.

1635381165379.png

Also, can you confirm the model switch is a Southwire 40100? (If it is a 40100, it is good news. A 40100 will switch neutral so my concern about connecting neutral in to neutral out is unfounded. They would be kept separate. (I feel silly for not looking up the 40100 earlier)
 

Lt.Dan

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Is this a picture of the inside of your transfer switch? It does not seem so because the case and background look different than the other pictures. Furthermore, this only shows 120V for the grid power in and I thought you had 240V for the shore power plug.

View attachment 70454

Also, can you confirm the model switch is a Southwire 40100? (If it is a 40100, it is good news. A 40100 will switch neutral so my concern about connecting neutral in to neutral out is unfounded. They would be kept separate. (I feel silly for not looking up the 40100 earlier)
The picture above is not mine, but it is 240v Split Phase. It has 2 hots (red and black) a neutral (white) and ground (green).

My transfer switch is a 40140, Is that still good news? Lol
 

FilterGuy

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My transfer switch is a 40140, Is that still good news? Lol
I think so..... I could not find a manual on the 40140.... but I did find a pic from ebay that looked like it was a 3 pole switch.

When you get a chance, shoot us a pic of the insides of it.
 

Lt.Dan

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I think so..... I could not find a manual on the 40140.... but I did find a pic from ebay that looked like it was a 3 pole switch.

When you get a chance, shoot us a pic of the insides of it.
Its a little difficult to get to mine, as I have to empty the basement and I just put it all away 🤣

I dont have a manual for it either,, like it didn't come with one? Lol. Here is a pic of a new one. Exact model as mine, 40140.

Screenshot_20211027-181744_Samsung Internet.jpg
 

FilterGuy

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OK.... Good. That is a 3 pole switch.... and that is good news. It eliminates the possible problem I had imagined of the in and out neutral being tied together.
 
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