using 110 receptacles for 12V. Warning!

System · October 2007

Gawd, I wish someone had told me. I have had endless problems lately with my system, no matter what I do.
Finally, tonight I realized I had a wiring fault. A bit of frenzied investigation revealed that neg. 12V current was being dumped into my ground wire.
When I built my cabin, I thought I would be able to get on the grid, and wired it for 110 with standard sockets with grounds.
Now I figured out that the ground wires are contiguous with the + slots in the receptacles! When I converted the receptacles to 12V use, I didn't know that, and left the ground wires connected.
Now I got to disconnect some ground wires.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Er, wait a minute. I made a mistake. I should know by now that ANY logical explanation could never work for matters electrical.

I ONLY get continuity between the + slot and the ground. Not the - slot and the ground. So how did 12+V of - current get in my ground?
And yes, I wired the 12V so that the + side is the shorter slot on the right.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Something is definitely not making sense here. Neither one of the current carrying slots in a standard 110 Vole receptacle are connected to ground at the outlet. What you will probably find is that your "110 volt" circuit breaker panel has the "neutral" which should feed the wide slot of each receptacle, bonded to Ground inside the panel.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Thanks, Wayne. I did the wiring myself, and i ain't no electrical genius. I'll check the breaker box in daylight tomorrow.

If I touch one probe of the DMM to the ground wire at the receptacle, and the other to the small slot, I definitely have continuity.

After I posted last night it occurred to me that the way the - juice gets in the + slot is, duh, because anything plugged in and running would naturally bring the flow of electrons to the + slot.
And the only reason these electrons then went down the ground wire may be because I created a circuit there when I put 1 prong on the ground rod (or ground) and 1 prong on the + terminal.
It probably would not flow there otherwise.
Shoot, I was getting 11 volts with the - prong stuck into the DIRT several inches away from the rod.

icarus · October 2007

Re: using 110 receptacles for 12V. Warning!

For a whole variety of reasons (code compliance one of them) you really shouldn't engergize 120vac 15amp recpticals with 12vdc. It is only a matter of time before someone (maybe even you,,,I speak from experiance) will plug in the wrong load to a give receptical than then you will have trouble. One way that is legal, as well as safe, is to replace the 120vac 15amp outlets with 120vac 20 amp outlets.(Nema 520 type) That way you cannot plug in a 120vac line cord into the receptical. It is my understanding that this is legal as long as there is no 120vac in the building. ( I understand that you may not care if it is legal or not, but you should make it safe).

As to your problem it sounds like you have a grounding problem somewhere. If the "white side" of the receptical is grounded at the panel as well as the grounded side you shouldn't have any problem, if your batteries are also grounded on the negative side. Perhaps there is something I'm missing.

Icarus

mike95490 · October 2007

Re: using 110 receptacles for 12V. Warning!

The narrow slot is supposed to be the "hot" (black) wire. Harder for kids to get a paper clip into it.
The wide slot is supposed to be neutral (white), and only tied to ground in the breaker panel.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Wayne from NS Cana wrote: »

What you will probably find is that your "110 volt" circuit breaker panel has the "neutral" which should feed the wide slot of each receptacle, bonded to Ground inside the panel.

Actually, Wayne, I just remembered something. When I originally wired the cabin, I ran separate lines for 12V. Then later, since I was not able to get on the grid, I retro-converted 2 of the 120 lines to 12V, leaving the other 2 breakers for 110 for when I fire up the genny.
I had run 12V wires into the box for such an eventuality. Not bad for a non-genius.
I wired the 12Vers directly in the box, bypassing the breakers.
All ground leads from the 4 lines converging in the box are connected together to the big ground wire.
And I have more 12V wiring, as I mentioned, that does not come near a breaker box, but those lines should not touch the breaker ones anywhere.
But I think the most problematic line might be one of the original ones that is not breaker-connected.

PS if you like cool pics of natural organic cloud formations, check out my site
http://www.loohan.com/spew.htm .

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

icarus wrote: »

For a whole variety of reasons (code compliance one of them) you really shouldn't engergize 120vac 15amp recpticals with 12vdc. It is only a matter of time before someone (maybe even you,,,I speak from experiance) will plug in the wrong load to a give receptical than then you will have trouble. One way that is legal, as well as safe, is to replace the 120vac 15amp outlets with 120vac 20 amp outlets.(Nema 520 type) That way you cannot plug in a 120vac line cord into the receptical. It is my understanding that this is legal as long as there is no 120vac in the building. ( I understand that you may not care if it is legal or not, but you should make it safe).

Yeah, I'm a mess. I don't remember whether they were Nema 520 or not, but when I checked the local hardware store for alternative receptacles, the only ones they had cost like 4X as much.
I put conspicuous globs of white silicone to plug the ground holes in the black receptacles on the 12Vers. And I live alone. And I never use 110 here except when the genny is running, which is seldom. And there are no codes in my county for residences.

As to your problem it sounds like you have a grounding problem somewhere. If the "white side" of the receptical is grounded at the panel as well as the grounded side you shouldn't have any problem, if your batteries are also grounded on the negative side. Perhaps there is something I'm missing.

Icarus

Now I'm really confused. The white leads in the box are on a bus bar. Are you saying I should connect the ground to this?

And I'm not sure what you're saying about batteries grounded on the neg. side.
The - 12v is on the left (large) slot of the receptacles, but unless that's what you're talking about, my batteries aren't grounded.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Oh, I see Mike is saying the same thing about Grounding the white side at the breaker box...

But before I do that, I'll wait for a reply about the battery grounding.

And since the 12v isn't even really part of the breaker box, I'll have to find another way to ground the white ones.

icarus · October 2007

Re: using 110 receptacles for 12V. Warning!

If I am reading you correctly you have 120vac and 12vdc in the same breaker box. Once again this is a serious no-no. Consider doing a seperate panel for the generator circuits. (Code issues not withstanding your lack of need for compliance, it is a good idea to use good wiring methods thoughout any installation.

As to the "white" wire and ground. In a typical installation, the white wires bond in the panel to the neutral bus bar. That bus bar may or may not be bonded to the grounded bus bar, and hence to "ground" at the panel. If it is not bonded to the grounded bar at the panel, it grounds at the transformer on the pole. Hence the white side is ultimatly grounded in any installation

Icaru

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Thanks, Icarus, I will go ahead and run a line from the ground to the bus bar.
I presume this is what I should do even in my atypical situation. This puts a direct connection between the juice in the bus bar and the ground wires still in some of the 12V receptacles.
Should I then disconnect the ground leads going to the 12V receptacles? Hmm, I suspect I know the answer to that one already...

Inside the box, in order to put the 12V line separate from the 120, I would have to run the 12V wires out of the box through drilled holes and mount another box in my overcrowded little closet. Or not even mount another box, but just connect the line wires to the incoming wires outside instead of inside the box.
But as it is, there's already a good inch between the wires of different voltages.

mike95490 · October 2007

Re: using 110 receptacles for 12V. Warning!

I think you have another serious problem, if your white wire is going to the skinny slot of the outlet. Bad. It should go to the wide (tall) slot.

BB. · October 2007

Re: using 110 receptacles for 12V. Warning!

Remember, there are no standards for using a 120 VAC socket with 12 VDC...

But, White/wide blade/silver-screw (neutral in AC wiring) is grounded at the neutral buss bar/metal cabinet and a wire ran from the buss bar to your ground rod and/or cold water pipes.

The Green Screw (ground lug/blade) is run with a separate wire (insulated or bar) eventually back to the panel, all green/bar wires bonded together (buss bar or local bonding screws) and eventually will makes its way to the neutral/ground rod/ground rod connection. Do not bond the white and green/bare wires anywhere else except in one spot (typically at the main panel). Otherwise, you could overheat the safety ground wire(s) by over current (from too many loads going through the safety ground instead of the white wire).

The ground wire must be large enough gauge to safely trip the breaker/fuse for the hot lead. Also, it must be low enough in resistance to trip the breaker/fuse.

Color wise--Black/Red/colored wires in AC wiring are considered to be hot on different circuits and White is neutral (eventually ground). Of course, this does not match DC wiring specs. Best thing to do--use some colored tape where the wires are connected... Use Red for +12v, Green for safety ground, leave it white (???) for -12v.

When connecting your 12 vdc appliances and your three prong plug (+/-/safety ground)--you may have an issue. If your appliance has a plastic case and a +/- lead, then just connect to the +/- leads of your outlet.

If your devices has a metal case that is grounded to the DC "-" lead, then connect your device to your outlet's +/- leads.

If your device has a floating metal case (not connected to DC +/-), then you probably should connect the case to your safety ground (green/bare ground wire).

In reality, you probably don't need the safety ground connection in your 12 VDC power distribution system... But if adding a safety ground connection to any of your appliances make sense, it should not hurt (again--always first checking that the safety ground is isolated from +/- power terminals).

-Bill

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Bill, no, the white side goes to the left/long slot. the only way electrons got to the short slot and hence the ground wire was via plugged-in items. When I unplugged everything, there was no longer continuity between the + and the ground in the receptacle.
In fact, now I can't duplicate finding continuity between either slot and the ground, which leads me to suspect that I got confused about what I had measured. Probably I had measured voltage between the + & ground, not continuity. Except then, where would the voltage have gotten into the ground if there is no continuity with the slots?

I did run a wire from the bus bar (only used for AC) to the ground, but it didn't help anything.

Thanks for all the info, Bill, but I hardly run anything on 12V that draws significant current.
My main ground wire is 4awg, I think. There are only 2 AC white leads on the bus bar, and the only time I use AC is when I run the genny for a power tool.

I got the whole system disconnected and am trying to find out where the problem is.
On top of that, my new Tri-Star relay driver appears to be malfunctioning, even when disconnected from everything except clean direct lines to the batteries.

Man, i love frittering away the hours on electrical stuff.

System2 · October 2007

how to trace wire faults?

Maybe some of you veterans can help me with this.
I am using the ohm function of my DMM instead of the continuity tester, on the theory that if there is a weak connection, I might see anomalously high impedance in a line.

I tested the most suspected lines: the 2 original 12V recetacles, not tied to the breaker box. They are on 2 different walls, but are continuous with each other. And buried under sprayed-in foam insulation and drywall, using twist connectors but no way to access them. Another no-no, i know. I suspect a connection could have gotten weak in there.

There are 2 wires sticking out of the wall that go to this wall wiring. This is where my juice normally runs into the wall, but I have that disconnected.
So first I checked the - one in there against the - slots in the 2 receptacles. Got about 1.1 ohm on each. Then tested the + line, and got ~2.2 ohm on each. Is this enough difference to indicate a fault?

The wire length is not more than 20', and the wire is solid 10 awg.

BB. · October 2007

Re: using 110 receptacles for 12V. Warning!

1.588 ohms per 1,000' for 10 AWG wire at 70F (according to the spread sheet in the General Solar Topics section)...

The 1.1 or 2.2 ohm readings are probably not real accurate. 20' of wire would only have about 0.02 ohms of resistance--very difficult to measure with an ohm meter. It may be real, or it may be the result of bad electrical connections, or just errors in probing the wires.

Is 2 ohms enough to cause you a problem? Depends on how much current is being used and the operation range of the device connected.

For example--a 1 amp draw will drop 2.2 volts on your circuit (V=I*R=2.2 ohms*1 amp=2.2 volts)--may be enough to stop many 12 volt items from working correctly. Add this to the 1.1 ohm return run, and a 1 amp load will have 3.3 volts of drop (12 volts in, 8.7 volts out) and not many 12 volt items would run on the voltage available at the outlet.

But, that is based on your (probably) less than accurate ohm meter reading. You would be better off connecting a known load (like a 12v 12 watt/1 amp filament lamp or an electric motor with a fan--some consistent load) and measuring the current and voltage drop and calculating the resistance from R=V/I.

-Bill

icarus · October 2007

Re: using 110 receptacles for 12V. Warning!

Bob's got it right on.

It seems to me it is time to start from the begining. Diagram your 120vac and your 12vdc wiring, and starting from the source, (battery/panel/generator) start testing one box at a time with everything else down stream disconnected. Test voltages at each box, connecting the next one in the string. (It is far from the original post, I'm not entirely clear what the problem is).

Remember the adage(s) Keep it simple stupid (no offence meant!) and avoid the ready, fire aim. If you test things logicly you will eventually find the problem.

Good luck,

Icarus

BB. · October 2007

Re: using 110 receptacles for 12V. Warning!

Icarus,

Bob?

Loohan,

Also, if you are having problems... Take that 12 volt (12 - 50 watt) filament bulb and put it in series with the + lead from the battery (or to the distribution box). It will prevent any shorts/fires (limit your current to about 1-5 amps), and you can measure voltage (and even short +/- together and make sure the bulb burns at full brightness when shorted--i.e., good solid connection (otherwise the bulb should be off if not shorts) and see where your issues are.

-Bill

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Thanks guys.

I put the system back together bypassing the suspected wiring (the in-wall wiring for the 2 original 12V receptacles) leaving me with the other receptacles working (that were converted later).
I work weekends and won't be able to work on this again until Monday. I'll know by then if my guess is right. Because the battery will be charged up better.

Let me back up and describe the problem, as I don't know what kind of fault would cause it.

Even with 2 new batteries, new Morningstar TS-45, and 160 watts of PV, I could never fully charge the batteries. I'm only using 2 Trojan T-105s. Even with sunny weather and running virtually nothing on it, it would never fully charge, so I couldn't equalize it. And I could completely drain the batteries by running hardly anything overnight.
What could cause such an apparent loss?

Here's an excerpt from an email I wrote Aug 13 with technical info. This has been going on over 3 months.

(quote from email)
So I bought 2 new Trojan T-105s, which cost $207 something with tax. Ghasp! If I had bought when I first noticed the others were bad, I could have saved a bunch. I have not tried equalizing these yet.

I just measured the outputs from the PV wires where they end at the controller in the cabin. Totally clear day, but extremely hot. We are in a heat wave, and the panels must be baking.
Nonetheless, I got 17.18V from the panels, which is near the rated max of one of them, but the other is rated around 14V, so I'm surprised it's that high. Maybe the lower voltage doesn't pull down a higher voltage.
Amps are 8.9.
I guess this is pretty good. I thought heat reduced PV efficiency.

icarus · October 2007

Re: using 110 receptacles for 12V. Warning!

Sorry 'bout that Bill,,er Bob, or,,,

Loohan,

It sounds like you should invest in an meter to check the system. If you can't charge a couple of trojans something is sucking them down!

Icarus

BB. · October 2007

Re: using 110 receptacles for 12V. Warning!

Loohan,

What brand/model of panels (sorry if you typed it before--did not see it on this thread).

When you measured 17 volts at the panels--What was the current flow into the batteries (at that exact moment)? What was the voltage at the battery.

Basically, if you have voltage and no current flow the panels will read high voltage.

Assuming that Morning Star TS-45 controller is a PWM (not MPPT) and you have maximum current flow (batteries need charge--below 13.5 volts or so), you should see 15 volts or so maximum (or less) at your panels. Basically, if the batteries are able to accept all of the current, the TS-45 controller should be just like a switch from the battery to the solar panels, and the solar panels should have pretty much the same voltage as the battery (until the battery nears fully charged and the TS-45 starts tapering off the charge current).

The 14 volt panel should not put out much current once it is above its rated 14 volts...

Also, is your meter working well? Calibrated (check it on your car battery and see if it is anywhere near accurate). To be real useful in checking your battery charge/voltage--your meter needs to be accurate to +/-0.05 volts (or better).

Something does not sound right... If you are reading 17 volts and 8.9 amps (151 watts) and you have no loads on your batteries--they should be charging.

8.9 amps / 220 AH =4% --

That is a pretty minimum size solar array vs battery capacity--A "dead" battery bank would require 24 hours of sun to fully charge (6+ days of full sun--depending on where you live/weather/etc.)...

Are you checking with a good hydrometer (and temperature compensating the readings)?

-Bill

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

I do have a cheap DMM which is somewhat close; I've used it a fair bit lately on various things.

I think I created some confusion in my quote from my Aug email:
"I just measured the outputs from the PV wires where they end at the controller in the cabin. Totally clear day, but extremely hot. We are in a heat wave, and the panels must be baking.
Nonetheless, I got 17.18V from the panels, which is near the rated max of one of them, but the other is rated around 14V, so I'm surprised it's that high. Maybe the lower voltage doesn't pull down a higher voltage.
Amps are 8.9."

Note that I said "I just measured the outputs from the PV wires where they end at the controller in the cabin." Then later I said "I got 17.18V from the panels" by which it may not be clear that I still meant at the ends of the panel wires where they end in the cabin. So the 17.18V and 8.9A is what I got coming into the TS-45.

What I think is that the reason the batteries aren't charging is that I'm losing some juice somewhere somehow. I just don't know enough about electricity to know whether it's possible to just lose it like you can water or gas, or what would cause that.

OK, I worked until late PM today and yesterday. Came home after there was no more sun on the panels.
There was ~12.6V measured at a wall socket when I got home yesterday. This was despite the fact that I had bypassed the wiring I thought was suspect. And unplugged everything.

So I bypassed ALL the house wiring last night,
and left it that way until I got home this PM after a very sunny, clear day. Now when I reconnect the load briefly to measure at the wall socket, I get 12.9. Which is the best I've seen in some time.

I guess I will keep the load disconnected as much as possible, and hopefully nurse the batteries back to a full charge so i can equalize them.

I know that I don't have the best battery/PV ratio, but I need 2 batteries to get 12V, and don't want more panels right now.
You see, I actually get by on very little electricity, so I normally wouldn't run down the batteries too badly. the reason I'm having problems is (I think) in my wiring.

So I'll try to nurse back those batteries, and meanwhile check those other wire lines more closely.
I'll try bypassing them, and only hooking up the lines I bypassed before.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Well, I left the original 2 12V lines hooked up overnight, and lost virtually no voltage. So the problem is somewhere in those other 2 lines that I later converted, and I did find one anomaly on one of those lines:
One of the outlets had the polarity accidentally reversed. This was not even a wall receptacle, but a cord-end receptacle on a cord running outside so I could use power tools outside when I fired up the genny. And I had used this outlet in the past, even a couple times with a polarized heavy-duty 120V drill, and never noted any problems.
I had not used the outlet at all since I had to convert the entire line to 12V.

Actually, that was 2 such drills. The first I had borrowed, and it stopped working while I was using it, after seeming to work fine at first. It just quit completely. Now I wonder if that was my fault.
But I used the 2nd one at least twice with no apparent problems.

But I don't see how it is possible for a reverse-wired receptacle, not in use, to cause apparent losses of electricity.

I used to rent a room in a house that had most of its outlets reversed, which did not seem to cause any problems with most things. That was quite a house. The carpentry work was equally adept.

I did not detect any abnormal ohmage in any of these lines, FWIW.

And now I'm in the midst of overcast weather, so I don't want to experiment until I get more sunny weather.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Aha! Haven't had a chance to test those other lines yet, but I got some interesting info from the Morningstar tech guy:

"A ground connection that has accidentally been connected to the wrong polarity
will also continuously feed power directly to ground."

So I may have already found my problem and solved it, hopefully.

System2 · October 2007

Re: using 110 receptacles for 12V. Warning!

Yes, either there is some major leakage, or load that keeps draining the batteries, OR there is actually very little charge current from the panels, being pumped into the batteries, or a combination of both.

System2 · November 2007

Re: using 110 receptacles for 12V. Warning!

Well, I'm not sure I fixed the whole problem. It's doing better, charging more, but still not charging fully enough to where I can equalize.

I just realized that I had forgotten to reconnect my main ground wire to the ground rod (though the controller is grounded to the rod by a separate wire) and stuck my DMM down there.
If I hook up the + probe of the DMM to the + battery lead and put the - probe on to the ungrounded ground wire, I read 1.75V. Is this perchance abnormal?

Also, is there a specific type of meter for easy location of wire faults?

System2 · November 2007

Re: using 110 receptacles for 12V. Warning!

Is the battery Neg. connected to ground somewhere? Perhaps at another ground rod?
Normally the battery neg is earth grounded, so you should have read full battery voltage from battery + to ground.
Before you do anything, what do you read between battery neg. and that same gnd rod? One other thing, it's not at all a good idea to have two different ground rods, grounding separate parts of your system and not have those rods bonded together.
Finding less than 2 volts between battery + and the gnd rod, indicates either the batt neg is not earth grounded, or somewhere in your system the batt + is earth grounded, or perhaps both, each on it's own rod. If both, and the grounds are functioning well, that could be your current leakage - - through the earth from one rod to another. It would be very interesting to check for any actual current flow in any of the cables going to any ground rods. There should be NONE.
Wayne

System2 · November 2007

Re: using 110 receptacles for 12V. Warning!

There is only 1 rod, Wayne, that had tied into it 3 wires (1 from breaker box, 1 from the separate original 12V wiring, and 1 from the charge controller) all clamped together. When I reassembled things a while back, I forgot to connect the breaker box ground wire to the rod. So right now that's still off (for scientific testing purposes) but the other 2 are connected.

I get no read when I put the DMM on the neg batt lead and either the loose ground wire OR the rod and its wires.

Between the + terminal and the loose ground, I get ~1.75V.
Between the + terminal and the rod, I get 0.32V.

That tell you anything more? I don't think I have reversed polarity at any other outlets.

System2 · November 2007

Re: using 110 receptacles for 12V. Warning!

Halleluja! I just experienced my first-ever battery equalization event, and I'm so thrilled!

So hopefully, the batteries are getting enough juice now.

System2 · November 2007

Re: using 110 receptacles for 12V. Warning!

Great news!!! May things continue to work well.

System2 · November 2007

Re: using 110 receptacles for 12V. Warning!

OK, well, I guess I'll reconnect the ground wire, if no-one has any comments about my 1st post yesterday.

using 110 receptacles for 12V. Warning!

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