GORDIE'S NEW ELECTRICAL TROUBLE SHOOTING THREAD

[Melbo]

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

[Gordie Allen]

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.

[opus]

"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.

[Melbo]

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

[bevans6]

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

[Melbo]

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

[eagle19952]

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.

[Gordie Allen]

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??

[niles500]

Sounds like a bad neutral

[Melbo]

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

[luvrbus]

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

[Len Silva]

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.

[Seangie]

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

[Gordie Allen]

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

[pvcces]

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