RECAP:
After leaving Larry's we had an electrical meltdown of the frig cord (120v ac). About 10 minutes after switching to the inverter. Lots of smoke. I threw the main breaker and meltdown stopped.
FACTS:
Frig was running on inverter at the time.
Most damaged line by far was the ground. Ground plug was melted into socket.
My house batteries connect to a Victron Multiplus true sine wave inverter.
The house batteries are supposed to be grounded through the Multiplus; however, I get zero volts on my multimeter from Multiplus to chassis.
zero volts from positive battery post to chassis
12 volts from pos to neg post on all house batteries (I have 4 in parallel)
12 volts between pos and neg lines running from house group to Multiplus.
I can't get 12 volts from any house pos source to chassis
If I hook a 12 volt motor directly to the pos and neg posts of the batteries it runs
If I ground the motor to the chassis, it doesn't run.
I've cleaned and tightened my ground connection from the Multiplus - no current flow
Multiplus charges batteries from shore power.
I have a second 120 line that bypasses the inverter and goes to the second post on my main. That works fine when plugged into shoreline. I moved all my breakers to that bar.
OPINIONS NEEDED!!!!!!!!!!!!
My first impression is that you lost the ground connection for the batteries, and they tried to ground through the fridge cord. Huge difference in current between 12v and 120v, the ground current would have been far larger than a fridge cord could carry. I don't understand the "The house batteries are supposed to be grounded through the Multiplus;", my rule of thumb is everything gets independent grounds Neutral is a different matter, of course. If you can't get 12 volts from battery positive to chassis ground, I would say fix that with a cable equal to the largest positive voltage cable to the inverter, and get your batteries grounded properly. You can never have too many grounds. I would further say that something inside the Victron is fried, maybe a solenoid or breaker that makes the path to ground for the batteries. I don't normally expect to see fuses or breakers in the path to ground, but there is some reason to put one in, in some cases. I would expect that the Victron is going to need a service call, or a replacement.
edit: if the battery ground is through the inverter, the loss of battery ground and then the failed ground path through an inverter load is extremely plausible.
Brian
Not that I am saying it can't be done since I just don't know, I would certainly want my battery bank ground to the chassis anyway.
Gordie this is just a thought but is there any chance a "chassis ground" got left off during the mechanical repairs?
The reason I ask is because right after that repair is when all this electrical trouble started.
;D BK ;D
His problem is on the AC side our boat had 2 Victron Inverters the batteries were charged through the inverter only and had no other grounds except through the inverter the batteries were a direct connect to the inverter his problem is not on the DC side those send out all kinds of signals for the DC side
I hope his inverter is still under warranty the Victron is a hard inverter to get serviced or repaired not much in the way of service yet on a Victron ours always had problems and the guys in San Diego at the marina would rip me big time I finally replaced both to sell the boat
Gordie-
Any chance the AC cord ground out on the chassis somewhere? Or maybe if there was a short in the fridge and a metal part of the fridge was in touch with the chassis somewhere causing the 120v to ground out to the chassis DC ground?
Other questions -
1. Does the fridge still work?
2. Were your house batteries tied to the chassis/start batteries anywhere? Or just connected straight to the inverter?
3. Did you blow a fuse anywhere along the way? (I'm assuming the negative side of your DC circuit was not fused?)
I think Brian is onto something with the 120v side and the 12v side getting connected at some point whether it was in the coach or in the inverter itself.
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Right now I'm leaning towards Brian's theory and Clifford's opinion. The only ground is through the inverter. I'll add a second (maybe third!) chassis ground tomorrow and see if I can find a reason why I lost the Victron ground. No breakers tripped. Big 400 amp fuse on pos side to inverter is good. Hopefully inverter isn't fried. I'll replace the frig cord and pray that nothing else was damaged there. Victron is about 18 mos. old.
Have your ruled out your fridge? The compressor rotor could be locked or failing/hard start..
It was the ground plug lead that melted, and it doesn't carry any load normally. I looked up the Victron, and indeed the batteries are directly connected to it, positive and negative, and it provides the ground connection. In order for the failure scenario I am thinking happened to work, the battery path to ground would have had to be interrupted inside the Victron and somehow the fridge would have to have a direct path to ground from it's chassis so the ground current from the battery would have to find a path through the inverter to the house panel to the fridge. It now seems a tad unlikely, one would think the house panel would be grounded and the path would have stopped there. Unless the house panel used the same Victron ground as the battery, instead of a true chassis ground. Without knowing more about the Victron and the house panel install it's impossible to guess more. One would think the fridge was on a breaker, which should have tripped in an ordinary over-current situation.
I'll be really interested to find out what the actual answer to this one is! I see flaws in every scenario I can dream up to explain this.
Brian
Could he have a hot skin problem which would explain the ground melting the cord, Just throwing it out there.
Dave5Cs
Brian, and all
The 120 panel has an isolated neutral and its own chassis ground. That ground shows continuity to the chassis. The battery ground from the Victron appears to be open (not connected inside the Victron, so no ground). The Victron ground wire is 0000 and has a clean, solid connection at both ends. It also has continuity from the Victron to the chassis. The frig is on a 15 amp breaker, which didn't trip. My plan today is to add a direct ground from the battery pack to the chassis. I also bought a new cord for the frig. Hoping it still works. I'm currently using the side of the ac panel that bypasses the inverter. Other than limiting usage to avoid overload, are the other issues with this strategy? I know the neutral isn't balanced.
Dave,
By "hot skin" do you mean a voltage leak to the chassis? Would you measure this by testing chassis to shore ground?
I guess I would pull the Victron out, get it on a bench and open it up to see what the path from battery ground to it's chassis ground is, and why that path is open. It might be a fuse. The question is - if it is a fuse, why did it blow? If it's a breaker, you could see if it resets and then connect a battery and see what happens. I would only do this after making sure that the Victron is out of warranty and you can't talk them into helping you out. Have you called their support line, if they have one? Sadly I see a Magnum in your future...
Brian
Gordie yes I found that mine had hot skin because the ground plug was broken off indie the power cord i was using. I used a 120 volt tester and put 1 lead in the power cord hot side and the other negative lead to the metal outside of our coach and it light up 120 volts going through the metal. Fixed the ground and it has been good ever since.
Gordie - First of all, thanks for posting this and keeping up with this thread. Its really forced me to do my homework and check my electrical connections on my bus as well.
I want to clarify some things as the word "chassis" seems to be unclear as to if its the bus chassis or the inverter chassis.
My understanding is that a 12v system and a 120v system should never use the same ground. And I just wanted to clarify that when you say the 120v panel is grounded to the chassis that you are indeed reffering to the inverter chassis not the motor coach?
I'm also assuming that you have your inverter tied into your electrical panel and the inverter passes power through itself into the panel when power is external and when there is no external power the inverter then begins providing inverted 120v power.
The last thing Ill mention is tying the neutral and ground together. Most inverters do this inside the inverter. One thing I have noticed though is that on outback inverters they sell a "mobile" version that ties the ground to neutral when there is no outside source and disconnects that tied bond when the source is external so that the ground is properly tied when an external source is applied. Does this model of Victron inverter do the same?
Is it possible if the Victron doesn't automatically switch the neutral and ground that when it was tied to shore power something over time maybe damaged the neutral/ground bond on the 120v circuit inside the inverter which is where (maybe?) this problem originated from (and possibly why Cliff had a problem in the past with the inverter?)
Just asking questions to clarify and understand. I've got a good understanding of electrical but I'm certainly not an electrician and am quick to get an electrician involved if its something not crystal clear to me.
Thanks again - curious to see if you can figure this one out.
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Sean - ground is ground, it's the same for everything on the bus or the house or any other thing. In a bus situation your engine electrics use the chassis as ground, the house 12v or 24v system uses the chassis as ground and the house 120v system uses the chassis as ground. Chassis ground is tied to the inverter, the generator and the batteries as on-board power sources, and ground from the shore supply cord is tied to chassis ground on the bus.
Brian
I have posted this before --- 120 volt electric systems have three (3) wires -- 1 an ungrounded conductor (this is typically referred to as the HOT -- 2 a grounded conductor (this is typically referred to as the NEUTRAL ) -- 3 a grounding conductor ( this is typically referred to as the ground ). With that as a starting point the electricity flows out the HOT (referred to as an ungrounded conductor ) and back on the neutral ( referred to as a grounded conductor ) to the SOURCE of the power. The "GROUNDING' conductor ( referred to as a ground ) should NEVER carry electricity UNLESS there is a FAULT. The HOT and NEUTRAL make a CIRCUIT (that is a circle). The ground is only for mistakes. If there is is some kind of error -- mistake -- general mess up -- unconnected neutral -- brain fart -- or other type of incident the ground takes the electricity and is supposed to send it to "HELL" or other place where it is not going to bother us. A hot ground will LIGHT up the skin of your bus -- fridge -- appliance or ANYTHING else. An open neutral (i.e. no place for the electricity to go ) can make for electricity "searching" for somewhere to go. This can happen in DC or AC or ANY electrical situation. When this happens you can get FEEDBACK. This (in 12 volt) can result in half power to fixtures or (in 220 volt systems) over powering a system. I understand the statement that a ground is a ground BUT a ground is for safety ONLY and should NEVER be used. Find out what is working and what is not and of course have a good ground. BUT most importantly find out what is working and what is not.
HTH
YMMV
Melbo
All my systems are grounded to the bus. My over the road system (start batteries, external lights, reverse solenoid etc.)(12v), my house batteries (12v) and my main 120v panel. The inverter has a specific ground that goes from its "chassis" to the bus (12v). It also has an internal connection for the 120v ground wire (green), ie. it has lugs for black, white and green going in and out of the inverter. That green wire then goes to the ground bar in the main panel, my main panel has a ground wire bolted to the bus chassis as well. If it didn't, the panel would have an open ground when not plugged into the shore line. At least that's my understanding. Neutral (white) is isolated from the ground in the main panel, inverter, etc. throughout the system. Connecting my multi-meter from black to white gives me 120v, so neutral should be good. I just realized I haven't checked for continuity between neutral and ground. I should not have continuity there, correct? I'll check this in the morning.
"I read"...albeit skimmed with one eye.....that 120v and 12v were never to be run together. That meaning next to each other, wires touching, etc. It might have had something to do with bleed through. I honestly dont know. Thought I would throw it out and see if someone else could take off on it.
Opus
I tend to agree with you. I was searching for the thread about the hot skin on a bus. I could not find it. I would be cautious about how the circuits are grounded and wanting to know that the 12 volt DC and 120 volt AC are not sharing conductors.
If you can locate the thread about the "hot skin" there is some VERY GOOD information about what to avoid and why.
HTH
Melbo
It's kind of obvious, but - ground is indeed a load carrying conductor in typical DC systems - the load path to a starter motor, for example, is positive to the motor terminal and negative return through the grounded chassis. So saying that "BUT a ground is for safety ONLY and should NEVER be used." needs to have the qualifier "in AC house systems" or words like that. This is probably one reason why low voltage DC and high voltage AC are always to be run in separate conduits, and have a separation in a box, or separate boxes. With low voltage DC you have the option of using the chassis for the load return or running a separate negative wire all the way back to a central ground point, which I call "home-run" wiring. My bus is wired that way for the house, I put in a fuse box for 12V positive and a terminal strip for 12V negative, and every light or other load has two wires to it.
Brian
Yes Brian you are correct about my reference to the "grounding conductor". It only applies to 120 or 240 volt AC systems. Chassis grounds in low voltage systems are commonly used as a return path.
Thank You for pointing out that correction.
Part of the reason I believe the low voltage and house systems got mixed up as you originally mentioned.
Melbo
http://www.noshockzone.org/ (http://www.noshockzone.org/)
here is the hot skin info...and more.
I don't think tht is the problem, there might be an appliance that has internally shorted to ground...maybe the refer..i would not plug it in too my coach sources until I verify it's condition...
search mike sokol for those electric posts.
he answered all my e-mail ??'s....nice guy.
OK guys, this is what I've come up with. Tell me if it makes sense. I have a 50 amp shoreline that feeds into a two breaker box (50 amp each). BLACK and NEUTRAL (WHITE) go to the inverter. RED bypasses the inverter. BLACK, RED and WHITE then go to the 120v main panel. The RED side is a direct feed from shore line. BLACK goes through the inverter. I pulled the main breaker and wired the RED and BLACK directly to their respective posts to eliminate the main breaker as a suspect. Neutral goes to its lug as well. With all the circuit breakers pulled, I get 120v all the way down both sides of the panel. If I plug in a breaker (15 amp), I only get 60v on the load side. That's with every breaker. And that's with no load on the circuit. They're basically open. My thought is that something has crapped out along the path of the NEUTRAL inside the inverter, since both BLACK and RED share the neutral, both sides of the panel are messed up. Otherwise the RED side should be independent of the inverter and work fine. My next step is to bypass the inverter with the NEUTRAL and see what I get. If I don't get a voltage drop with the RED/WHITE circuit, then NEUTRAL is the problem. As an aside, the four stage charger works just fine when in "charge only" mode, so I can keep my house batteries charged for the little DC needs that I have (water pump and propane furnace). In the meantime, I'm running my LED lighting on one 15amp extension cord, and one mini split on another. This makes me a little nervous, as I'm depending on the shoreline breaker for protection. The LEDs draw less than 2 amps and the mini 9 amps. Cords are heavy duty and do not get warm at all. If I'm right, I plan on getting a 30 amp cord and run it straight to the panel, bypassing the inverter altogether, but keeping the charger portion available. Thoughts??
Sounds like a bad neutral
Rather than rewire anything here is what I would do in that situation.
Get and extension cord and a multitester. Locate the "neutral" "ground" and "hot" and label them on the outlet end of the cord with a sharpie so you know EXACTLY what is what.
Using the tester test between the extension cord "hot" and the neutral going in to the inverter. Then test between the extension cord "hot" and the neutral coming out of the inverter. You can also check the resistance between the "neutral" on the cord and the "neutral" into and out of the inverter. Lots of other things you can check BUT if there is a weak connection you may not find it unless you have a load tester to check with.
Keep us posted on what you find.
HTH
Melbo
P.S. be careful to check the setting on the tester when you change tests
When I lost the neutral to the house from the pole it smoked everything on 110v searching for the neutral it didn't bother any of the 220v items
Quote from: luvrbus on January 19, 2014, 08:41:57 AM
When I lost the neutral to the house from the pole it smoked everything on 110v searching for the neutral it didn't bother any of the 220v items
That is what typically happens when you lose a neutral. With the neutral open, all the 110 volt loads on one side of the panel are in series with all the loads on the other. If both sides were closely balanced, you would not have a problem. If they are unbalanced, the the side with the smallest load sees a higher voltage and the equipment is damaged. The neutral only carries the difference between the two sides.
Gordie -
I would test the following at each point -
Ground to Neutral - (0v)
Ground to Red - (~115v)
Ground to Black - (~115v)
Red to Black - (208 - 240v)
Red to Neutral - (~115)
Black to Neutral - (~115)
I would test these at -
The pole (baseline)
Before the inverter (black only)
After the inverter
Before the panel (black and red)
After the panel
And then at each breaker inside the panel.
Since we are all assuming you lost something in the inverter I'm thinking you'll see the variance post inverter.
I just had a similar problem where weird things were happening and it ended up being a neutral wire that wasn't 100% connected properly in my 50amp connector. Visually it looked fine but when I checked the voltages to the neutral I was only getting 80v instead of 115. I clipped the neutral and rebuilt the 50amp connector and that fixed it. I never would have been able to find that had I not checked the previous at each point.
The weird things were that some of my electrical items wouldn't turn on when the genny was running and then it started happening at the campground pedastal and I traced it back to the 50 AMP connector in the bus using the previous tests that a good electrician friend of mine told me to do.
Hope this helps.
-Sean
Fulltiming somewhere in the USA
1984 Eagle 10S
www.herdofturtles.org (http://www.herdofturtles.org)
Well, you guys were on the right track. I think it's a bad neutral path in the inverter. After checking all connections and re-tightening all the lugs, I decided just to wire the main panel directly to the shoreline, bypassing the inverter altogether. Everything works fine and tests correctly, including the outlet to the frig. Bought a new cord for the frig, but haven't wired it yet. Maybe later today. The good news is that the Victron has a two year warranty. We'll see if they honor it. Thanks for everyone's input. I'd be a lonely world out here without your support!
Gordie
Gordie, since the inverter typically uses a relay to switch the neutral when you plug in to shore power, there is probably a bad relay in the inverter. In the past, I have not had any trouble changing out a relay, so a repair might not be very serious.
For what it's worth.
Tom Caffrey
Thanks for the info Tom. I'll see what the seller has to say about the warranty and then decide to tackle it.
In most electrical installations, the neutral is never switched. It is a necessity in our conversions at both the generator and inverter. Of course, any switch, relay, contactor, or plug is a weak point in electrical work. We must remain vigilant that whatever switching method we use, the neutral is dependable.
Have you noticed if there are any error lights on the inverter? Victron has a nice decoder that lets you interpret what the various flashes might mean if there are any. They even just released an app version of the decoder.
I suspect you might have either a bad relay in the inverter, or something incorrectly wired elsewhere.
Have you confirmed that the circuit breaker on the fridge circuit is working correctly? Have you checked all your AC outlets with a circuit tester for open neutrals, etc?
I'm very eager to learn what failed here.
But... You are still under warranty, so you should be starting with the manufacturer. I've generally gotten good responses from knowledgeable folk when I've written to Victron with questions.
Keep us all posted.
- Chris
Chris,
No flashing lights on the inverter. I checked all the outlets with a simple outlet tester. Everything is good. Breaker for frig is good. I bypassed the inverter for now and have no issues when hooked to shore power for my 110v stuff. I have rewired the inverter with a 15 amp cord, and have the inverter on charge only. I plug it in every night to top off the house batteries. I have two 12v motors (water pump and bay fan) that run off the house batteries. It goes through the charging stages just fine. Since the meltdown happened as soon as we unplugged from shoreline, and I've had it working in both modes for almost a year running the frig, air conditioners, water heater, etc. I'm pretty sure it's the inverter. Will keep you updated on what I find out from Victron.
Gordie what size and length is the cord from the Battery bank to the inverter?
Just wondering if it is to small and or to far away and your power drops off to much to pull the power for very long? or your circuit s are not balanced and when searching for power the refrigerator get to much and finally burnt out?
Dave5Cs
Per Victron's installation instructions, I have two 000 in parallel running from both the positive and negative posts of the battery bank to the inverter - 3 ft. in length. Positive goes through a 400 amp fuse before getting to the inverter.