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How to Know AC Wire Negative vs. Positive

AgroVenturesPeru

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Long before starting our off-grid solar power installation, we had an electrician wire the house for outlets, lights, switches, breakers, etc. He left a couple loose wires sticking out of the floor to attach to my inverter to feed the house. How do I know which cable is positive vs negative?

Here's the circuit breaker from the inverter connection. Looks like my solar kit distributor labelled the positive? with a little red tape.

IMG-20210516-WA0007.jpeg

The inverter just has bolts for the AC connections that are labelled, "Line" and "neutral"
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This last picture shows the house's AC wires coming out of the tube from the floor.
 
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In alternating current, the concept of positive & negative doesn't exist. Instead, terms live live & neutral are used. The neutral terminal is usually at ground ('zero') potential and the live terminal can be anywhere in the range -170 V to +170 (in the US) with respect to the neutral line, switching from +170V to -170V 60 times second.

Both neutral & live wires are part of the circuit and must be handled carefully.

I did not click on the photos and have no specific comments on those.
 
The electrician wired the house, but I want to make sure there's a connection available to hook up my ground. I don't think the electrician left anyenpoint where I can connect the AC to my common grounding electrode
oOr is it sufficient ground to simply hook the 2 house ac wires to my inverter output? (the inveerter is bonded to all the other solar components and grounded to a common grounding electrode)
 
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No distinction between positive and negative since AC does both. But here are "hot" and "neutral" for 120VAC, and there is "phase" of the hots.

If two inverters are to be connected in parallel, you want the phase to be the same. If the inverters provide pass-through of AC from grid to load, they have to be in phase with each other so they don't cause a short between line 1 and line 2. Easy enough to check - with the breakers on their output off but grid present and inverters passing through grid, use a voltmeter. If two outputs are same phase, zero volts between them. If opposite phase, 240V between them.

You've shown two output breakers, each two pole.
Your inverter has Line & Neutral in, and what appears to be Line 1 out, neutral out, line 2 out.
Does that mean your inverter takes in 120VAC, puts out 120/240VAC out?

I would need to see more about the design to figure this out.

In general, you do NOT want output of inverter connected to grid, it would fight and blow up.
Input to inverter probably connects to grid, and inverter may synchronize phase and backfeed to grid.

I would expect a ground wire from ground bus of breaker panel to the inverter.

It looks like he mounted a 2-pole breaker labeled "IN" and two 2-pole breakers labeled "OUT1" and "OUT2". Here in the US, we don't switch neutral, only hot. Seems to me the 2-pole breaker switches both hot and neutral.
He has one pair of wires off each 2-pole breaker. So it pulled some wires to where your inverter goes? Are there also wires going to a breaker panel on the utility grid? I'm asking because I don't see wires on both ends of a breaker, like from utility panel to breaker to inverter.
 
Let me clarify a little bit. I'm way off-grid. There's no chance of being grid-tied. I'm using a Victron Multiplus 48/5000/70, which I believe is a 220V-240V version, because it's being sold for use in a country with a 220v 60Hz grid. (I haven't hooked it up yet to check the parameters).

In my situation I only plan to ever use the AC output1. I forget what AC output2 is for (it says somewhere in the Victron manual).

My solar power system has a cabinet at the center of the system which houses my Cerbo GX, busbars (including a common ground busbar), fuses, and the inverter circuit breakers from the photo in my first post.

I've spent so much time reading about solar (dc) that I haven't bothered to study Alternating Current. You've made me realize that one wire is Line and one is Neutral. It's a new concept for me. Luckily my distributor labelled each wire. The electrician, on the other hand did not.

A while ago (long before starting my solar installation) I paid a local electrician to wire the house we're building.

I just got done watching a Mike Holt course on proper grounding, which mentions bonding all the solar components, and I think also bonding the AC system, and then connecting it all to a common Grounding Electrode via a common Grounding Electrode Conductor.

So, here are the two things I'd like to find out:

1) Which of the electrician's house wires coming from the floor are Line and Neutral. Forgive me if you've already answered this somehow, and I'm just ignorant.

2) How to ground the AC system along with my solar power system. I already know how to ground and bond the solar power system, but I don't know how to integrate the grounding (or bonding?) of the AC system.
 
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In AC you're right 50% of the time, 30 times a second. JK

Not that it would be correct, but what are the wire colors you mention? Black and white? Sorry cant tell from the pic. Where is this electrician now?

What is the EXACT model numbers on the Victron?

Let's do a little more fact checking.
 
Just stop

There is no AC neg or pos

AC has hot and neutral. Neutral is supposed to be tied at one (only 1) point in the main panel, to ground.

Hot wire is Black
Neutral is supposed to be white
Ground is supposed to be green. These are all standards you need to know before you pick up a pair of wire cutters or a roll of tape.
 
Lighten up Mike, you'll live longer. If you can't handler a little jovial banter, up your health insurance. It was an obvious JK.

I've seen things strung together across other countries that defies explanation. People use whatever they have to work with and whatever is lesser expensive that would raise a Western brow, let alone be anywhere near any sort of code.

Best case scenario is that he still needs a ground leg for the A/C and his Victron is the right model and output for his locale. Those two wires sticking up from the floor may be hot and neutral, but both of those wires look black to me in the pic.

On top of that they are wired to a standard zip cord plug, being hand twisted together and then soaked in insulating black tape goo. Temporary I'm sure.

@ Agro - I can see your obvious investment in your infra and need to get things tied together. It seems like the question is still this > "Which of the two black wires for your inverter are supposed to be Line and Neutral?" and also "How to ground the AC system along with my solar power system?"

Can you answer the questions for Hedges and provide any sort of schematic of these systems and how they are supposed to interconnect?

Can you provide more pics of the system end to end from your solar system through the breakers in your box and to any outlets? Did the electrician install a physical ground rod and are there any green wires or grounds other than your solar system?

I would need to see more about the design to figure this out.
...
I would expect a ground wire from ground bus of breaker panel to the inverter.

It looks like he mounted a 2-pole breaker labeled "IN" and two 2-pole breakers labeled "OUT1" and "OUT2". Here in the US, we don't switch neutral, only hot. Seems to me the 2-pole breaker switches both hot and neutral.
 
I would suggest calling your electrician. Seriously, if connected wrong you will smoke your inverter at best, and could die at worst. The two wires in the last photo appear to be blue and black. Which of those is neutral and which is line will vary by country.

 
I have come to the aid of neighbors who's solar system had failed, and the lack of standardization was a nightmare. Nothing color coded, wrong gauges of wire, batteries wired incorrectly, and basicly a spaghetti mass wire with no labels whatsoever. There are reasons why everything should be color-coded.
 
I would suggest calling your electrician. Seriously, if connected wrong you will smoke your inverter at best, and could die at worst. The two wires in the last photo appear to be blue and black. Which of those is neutral and which is line will vary by country.

Yes, you're correct. One is blue and one is black. Neither are labelled, so I don't know which is supposed to be line and which neutral. I was told it doesn't matter. The other picture shows the pre-wired AC cables from the inverter going to the AC circuit breaker. Those are labelled accordingly: Line and Neutral. So that much I do know. The electrician definitely did not leave a third wire for ground for the AC (was he supposed to?), if so, now what? Please, I need to know. So-called professionals down here will cut corners, endanger your life, and cut themselves a paycheck all in a day's work. ?‍♂️


I've already wired everything else for ground on the DC side of things.
 
It helps if you have a schematic that was provided to them.
For regular house wiring, that is often a "one line diagram" because we know what 12/3 + ground or whatever means.
For this job, battery side might need more but AC side should be that simple.
 
Lighten up Mike, you'll live longer. If you can't handler a little jovial banter, up your health insurance. It was an obvious JK.

I've seen things strung together across other countries that defies explanation. People use whatever they have to work with and whatever is lesser expensive that would raise a Western brow, let alone be anywhere near any sort of code.

Best case scenario is that he still needs a ground leg for the A/C and his Victron is the right model and output for his locale. Those two wires sticking up from the floor may be hot and neutral, but both of those wires look black to me in the pic.

On top of that they are wired to a standard zip cord plug, being hand twisted together and then soaked in insulating black tape goo. Temporary I'm sure.

@ Agro - I can see your obvious investment in your infra and need to get things tied together. It seems like the question is still this > "Which of the two black wires for your inverter are supposed to be Line and Neutral?" and also "How to ground the AC system along with my solar power system?"

Can you answer the questions for Hedges and provide any sort of schematic of these systems and how they are supposed to interconnect?

Can you provide more pics of the system end to end from your solar system through the breakers in your box and to any outlets? Did the electrician install a physical ground rod and are there any green wires or grounds other than your solar system?

Almost.

For the first question I'm asking about the black wire and the blue wire coming from the floor of the house. I already know the inverter AC wires. They were labelled properly. The black wire and blue wire from the floor do not have a label, and the color scheme was not explained to me. That's my first question: Which of the house wires (the ones coming from the floor) is Line (Hot) and which is Neutral? I was told it doesn't matter which is which.

Yes. That is my second question.

Keep in mind, not to sound too harsh, it's possible this electrician is half-retarded, and doesn't remember how he wired the house. We did already confirm with a generator though, that the house works. The light switches turn on the lights and every outlet ran our blender that we used to test.

So, the electrician should've grounded the AC side of things? I made it clear from the start that we would be installing a grounding electrode, so please let me know if the AC side of things needs to have some sort of ground-wire coming out of the floor in addition to the black and blue wires that are already present.
Can you answer the questions for Hedges and provide any sort of schematic of these systems and how they are supposed to interconnect?
I'm confident in my solar install. I'm not worried about that. It's the AC side of things that has me worried. I've had too many people do crappy work down here, so I'm very suspicious. Yes, the solar is a huge investment.

So the AC side should have a grounding point at the main circuit breaker box for the house? I'm not sure the electrician left any way to ground anything at the circuit breakers. All my DC (solar is grounded properly, so not worried about that side of things.)

Is grounding the AC something that can be done "after the fact" or is it too late?
 
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We like a dedicated ground wire run to each outlet and device. That is used to make sure chassis is kept at zero voltage relative to earth, even if a wire comes loose inside and touches it. The breaker should trip and shut off the power.

 
uh-oh!!!!!! This sounds bad. I guess I got ripped off. I sure hope this criminal nation actually has a valid authority to oversee this matter. It looks like they just decided not to do what they were supposed to do. I guess I'm going to have to pay another electrician and cross my fingers that they're not a retard and don't screw us over again.
 
What do I need to do to protect all the electrical in my house? I don't want to die in a lightning storm from touching my refrigerator or something? I also don't want to lose my $16,000 solar system investment, because some irresponsible crooked electrician didn't wire any ground wires in my household electrical.
 
There ought to be electrical plans for electrician to follow.
We typically submit some plans to the city which they approve.
Without plans, it's hard to say what he was supposed to do.
I do it all myself, but then it is related to my field and I have year of experience.

To avoid damaging equipment, need to make sure PV voltage and polarity are correct before connecting, battery voltage and polarity are correct, AC voltage is correct and Line/Neutral are connected correctly.

For fire safety, breakers should be no larger than what "ampacity" tables say wires can handle.
We also have AFCI breakers (usually combined with GFCI) for fire safety.

For electrical safety, exposed hazardous voltages should be covered. All metal parts should be grounded (with a wire heavy enough to trip the breaker, might be smaller than the other conductors in some cases.)
We also have GFCI outlets now for shock protection.

Lightning protection is another issue, depends on conditions in your area.
Some people use lightning rods to catch and ground the strike.
Protection devices can be put on grid AC input and PV input.

Advice I've seen is to not touch appliances or plumbing during a storm. Never worried about it myself. It isn't so common here.
 
Ok...
what is connected on each conductor and where?
There may just be solar drops from a future solar line... to help, we need to know what the wires this electrician left you are hooked to.
 
What do I need to do to protect all the electrical in my house? I don't want to die in a lightning storm from touching my refrigerator or something? I also don't want to lose my $16,000 solar system investment, because some irresponsible crooked electrician didn't wire any ground wires in my household electrical.

I recommend finding electrical companies instead of individual contractors. As you just experienced, they can, and will do shitty jobs since no one oversees them in some developing countries.

A company with many years and projects behind, will more likely do a proper job, although of course, more expensive.

At the end of the day is your house, so i also recommend studding basic electricity so you can detect when they are riping you off or doing a bad job. In an ideal work we shouldn't need to do this, but i had simillar experiences as yourself and ended up learning a lot by fixing work of "electricians"... to the point that i can do my own installations if i want.
 
@AgroVenturesPeru - maybe provide some whole photos of your panel and a line drawing of the electrical system if you can. It is hard to tell what those breakers are hooked up to and probably a DIN-mount panel with custom wiring instead of standardized bus bars, etc.

As mentioned previously, colours will differ depending upon the country. Green is universally ground as far as I know. North America uses white for neutral and black for live, but since you are in Peru with 220V 60Hz, it will be different. Since you are off-grid, you should just have single-phase wiring. Is your generator you used to test it single phase?

For the first question I'm asking about the black wire and the blue wire coming from the floor of the house. I already know the inverter AC wires. They were labelled properly. The black wire and blue wire from the floor do not have a label, and the color scheme was not explained to me. That's my first question: Which of the house wires (the ones coming from the floor) is Line (Hot) and which is Neutral? I was told it doesn't matter which is which.
For it to work, it does not matter. For it to work safely it is CRITICAL to get it right.

The neutral will be connected to a grounding rod where it enters your house. Here is a quick screenshot for the grid connection for my house. Everything blue is the in the meterbox / switchboard. MCB = circuit breaker, SPD = surge protection device. You can see here the that grid power comes in on the red and black lines and the black line is grounded using a earthing rod that is a 1.2m copper rod driven into the ground. In your case, the grid connection is likely the generator.

1621678429514.png

Look for the earth bar to determine which line is neutral. The green earth busbar (EBB) should also run to each of your power points and to your inverter for safety as others have mentioned.

To determine which is the live wire (red in this diagram), use a volt meter between ground and the wire you are unsure about. If it is 220V then it is the live wire. If it is 0 volts, then it is the neutral wire. If it is a couple of volts then it is probably disconnected and you have inductive coupling.
 
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