# Basic wiring stuff

Solar Expert Posts: 143 ✭✭

OK, pretend you are a caveman unemployed recently from a prominent insurance company's ad campaign (I won't mention which insurance company but it rhymes with fico).  Now you have an idea of how much of a grasp I have on wiring and electricity in general.  Just enough, it turns out, to get me into trouble (probably).

I am having trouble with figuring out how the neutral wire works. If the current comes in on the black 'hot' wire, I thought it returns to the power company on the neutral?  This is a/c, of course, so it will reverse directions 60 times a second, but if we isolate each movement of current separately at 1/60th of a second and freeze it, that looks like a circuit to me.  But I also see that the ground is connected to the neutral circuit... so if the current comes 'in' on the hot but reverses direction all the time, that means half the time it is coming in on the neutral?  but if the neutral is connected to ground, why wouldn't it simply short to ground half the time?  Sorry for the retarded questions, there should be a baby question area for me

Also, for 220v, I took both the hots and put them into each side of the receptacle and didn't use the neutral.... so how is that current going back to the electric company? I know my welder works, but not how...

thanks,

walt

• Solar Expert Posts: 795 ✭✭✭✭
edited April 2016 #2
Hi Walt,

The neutral wire is a ground wire, however it is the only designated ground that should normally be carrying current to ground. As such it is grounded in the main panel only. No other sub panel or circuit should have a neutral to ground bond.
So a 120 volt circuit is the electromotive force alternating between a 120v feed and ground. A 240 volt circuit alternates between 2 120 volt feeds. So, it's not like it goes back to the electric power company. Imagine we are holding an 8 foot rod between us. I push it then you push it. This goes back and forth. This is like a 120v circuit. If we hold 2 rods and do the same except the right hand pushes and the left hand pulls, this like a 240v circuit. So the actual power that you are using is in distance that your hands travel in the analogy.

Rick
4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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edited April 2016 #3
Raj174 said:
Hi Walt,

The neutral wire is a ground wire, however it is the only designated ground that should normally be carrying current to ground.
NO   NO   NO    The Neutral wire (the white insulation) is the "return" for the Hot (black) wire,   It happens to be bonded to ground at 1 point in the main panel.
Ground (the bare or green wire) normally carries NO current, unless there is a FAULT .

North American Split Phase power system uses a center tap transformer (on the power pole or a ground mount transformer box) to produce 240VAC with a center tap as Neutral.  So either Hot gives half of 240V  (120) referenced to the center tap.  Hot to Hot gives 240V and the neutral is not used

https://en.wikipedia.org/wiki/Split-phase_electric_power   has some explanations.

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In other words L1 and L2 are in phase. The discrepencys in L1 and L2 loads get averaged out over all the users of the transformer, to a point where it is near enough. This is known as diversity.

Something similar occurs here, theres no split phase, but house 1 in the street will go on the yellow phase, house 2 will go on blue, and hour 3 on red. While those 3 houses will never use the same amount of power once you add another 10 trios of houses it comes out near enough.
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• Solar Expert Posts: 143 ✭✭

Still going over my head, I've never seen the inside of a transformer; I can see the schematic representation of one and sort of understand. Is there a basic manual that everyone uses as a primer that is good? maybe a link to an amazon book I can order, or a website?

I plan on going off grid eventually; right now I'm still connected.  When you get your battery system set up, is the easiest way to have an electrician install a separate disconnect switch for grid power? I didn't want to keep the grid as backup so did not order a grid tie inverter, I got a VFX3524...  I'm in Hawaii and the house is roughly 18 years old, power delivery is by buried cables and my meter is along my garage wall... does anyone have any ballpark for what installing a disconnect switch would cost? I'm estimating this will happen in 3 years, after I sort out my loads and supply capabilities better. But in the meantime, I can't tie into the house distribution lines because they are still connected to the grid.  This leaves only establishing other, discreet distribution of solar generated power, or else installing some sort of grid disconnect or a transfer switch of some kind? I guess that would have to happen at my breaker panel and not near the meter... if I can get some sort of transfer switching system, I guess no disconnect switch would be needed, I can simply order termination of service from the electric company and they will come over and unhook me.

Getting an electrician to install a Transfer Switch system--You can be talking about some big money.

You are looking at a 3.5 kWatt AC inverter--How many "branch circuits" are you wiring up?

You have a choice of putting a transfer switch "in front" of your main panel. Or you can put transfer switches per branch circuit on the output of the main panel. Some examples (just to give you some ideas):

Main Power Transfer Switch

## Midnite Solar 60 Amp 240 Volt Dual AC Manual Transfer Switch

Per circuit transfer switch:

http://www.amazon.com/Reliance-Controls-Corporation-31410CRK-10-circuit/dp/B000HS2L3O

The VFX3524 does have an internal AC Transfer switch--So, in theory, it could replace the 60 Amp transfer switch.

A big issue that you may have... Most homes in the US are wired for 120/240 VAC split phase. Your Inverter is a 120 VAC only unit (I think).

So, do you have only 120 VAC appliances? Or do you have any 240 VAC units (well pump)?

And, I would suggest, that you would need a backup AC genset too (which may be 120 or 120/240 VAC or several 120 VAC circuits).

This is a big project--Depending on your power needs--And what you want to for backup (no utility eventually--Will family accept "waiting for parts" if no power).

Walking away from the grid is a big deal... You can have issues with the local building department "red tagging" your home (code may require utility power). And, if you disconnect from the grid, you could get hit with payments to the utility (stranded infrastructure), and possibly the utility may pull poles/transformers--Leaving the next (eventual) buyer of the property with trying to get utility power back (and the associated costs).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 1,218 ✭✭✭✭
Do you know what a voltage divider is? Because the two hots are in phase, you can just imagine your house as the 3 sets of loads in the diag below:

`L1--------+-------+          |       |        120V      |           |       |N --------+      240V          |       |        120V      |                |       |L2--------+-------+`
L2 is therefore negative to neutral. Anyway now that we know what your driving at, the question under the question as it were, your choices are:

- swap the VFX for a Radian or other hybrid inverter
- get an autotransformer for the VFX, so you can make 120/240
- write off 240, and organise your main L1 and L2 to all work on the single 120V. This is easy enough when off grid, because with some caveats you can parallel L1 and L2 circuits together. The major caveat is you have to check your neutral wiring is wired properly, as some older wiring relied on smaller neutral current. And, the transfer swtich idea complicates this rather significantly.
- just use some dedicated offgrid submains as bill said, and wire those as above.

1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
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• Solar Expert Posts: 143 ✭✭
edited April 2016 #9
Thanks, guys.  Bill, I am in the middle of a subdivision, my street probably has 20 or so houses on it; so the infrastructure changes would be minimal, probably amounting to disconnecting the meter since both neighbor lots on either side of me probably share the same high tension service infrastructure.   Land is expensive in hawaii so the houses are built right up to the property line in some cases. Lot size in my area probably averages 6000 sq ft, very small by mainland standards and everyone on my street has electric service and won't be changing that, I'm the only crazy guy

I've thought along the same lines for the 240v and have been slowly finding ways to get around that. My only need for 240v is the stove and water heater; for the water heater, I'm trying to put my panels together for the direct PV to water heater gadget I got off ebay. Someone else on my island has one and he says his works pretty good (sold by username techluck on the 'bay).  I was going to try for DC water heating elements, but was told the techluck gadget works better and can support 3 panels instead of 2 for the DC element.  The user who has one has indicated his 80 gal tank gets warm in around 3 hours using 2 panels. So for me, that's fine... and that will take my water tank offline, leaving just my stove with 240v requirement.  I got an induction hotplate off amazon for \$70 and its working great, using 120v and around 1300w max. It cooks just as fast or faster than my old resistive stove elements and is much more efficient, needing only 120v.  I've set it up in the kitchen and forbidden the family to use the stove; must use the hotplate!  ...its been working out. Only very rarely do we turn on the stove now, only when we need the oven, really. I'll pick up another induction hotplate for a 2nd workstation for cooking and retire the stove.  Haven't decided what to use for an oven yet, but between the microwave and the induction hotplate the kitchen 240v is retired and now requires only 120v.
The only other 240v thing I have is my welder and lathe (same outlet), which I'm pondering on. They don't see much use, of course; only very sporadic needs for those... I have a nearly new chinese Champion (knock off of the honda engine, VERY faithful copy... so faithful Champion lost a copyright suit by Honda on these engines which are copies of the GX series of Honda engines) generator, 4kw (non inverter) that I see some people on the net say can be rewired very simply to produce 240v, so that might be an answer for my lathe and welder if only small currents are needed (i.e., not heavy welding). If it does not suffice I'll look for a larger genny with 240v to power the welder occasionally.  I also have 2 small 'suitcase' Ryobi 2200w (each) super quiet gennys, which aren't as quiet as the Honda eu2000i, but was half the price... for about the price of a new eu2000i, I got both Ryobis and they have served just fine. I got 2 so I can gang them for around 46amp sustained output if needed (they are inverters).

I am leaning toward the multi branch circuits after the main panel, but haven't really decided yet. I haven't yet gone through the VFX3524 manual, its kinda big! so good to know it has an a/c transfer switch inside it... thanks for the info.  I have just found some Reliance? transfer switch 'kits' on amazon... wonder how much the electrician would cost to install one? looks hairy.
What is your monthly power bill now (kWH per month)?

And, you can run into other issues with extreme energy conservation... One is that if you do not get your water heater hot (>140F) regularly, it (and your hot water lines) can become a breading ground for Legionella.

Hot Water Temperature: Legionella & Scalding Prevention

My belief is that electric water heaters are more prone to Legionnaire disease (at lower temperatures), because just two cal-rod elements get hot rather than as in a gas water heater vs the entire bottom and center pipe (stack) become hot enough to kill Legionella. Using solar thermal hot water and/or a heat pump based water heater is usually a good solution.

6,000 sq ft lots is not bad--A typical lot is 5,000 sq ft (50x100 ft) or even down to 4,000 sqft for newer homes.

In any case--Running a generator for backup power may cause grief with your neighbors.

Energy conservation is a huge start before going off grid--And can be a big help if you have expensive electrical power.

If, extreme conservation and/or using lots of solar becomes big in Hawaii--You will probably find that your utility will (or already has begun) to change their entire rate structure. Instead of a cheap monthly connection charge and (relatively) high \$/kWH--You will see them pushing towards high monthly charges (\$40-\$50+ per month) and "cheap" \$/kWH charges. This makes GT solar and conservation much less effective as a means of controlling your costs.

What are the chances of using alternative fuel sources for cooking/hot water (propane or other)? Local code and conditions may make propane or other on site stored fuels impractical/unsafe.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 143 ✭✭
edited April 2016 #11
Thanks Bill. I've never heard of bacterial contamination as being a threat in your water heater! Will read up on that. I think the local water supply has trace elements in it which obviate that, though.
My daily use was around 23-24kwh a couple years ago. By turning off the water heater at the breaker panel most of the time and just batch heating before use, and the induction hotplate and fridge-to-freezer changes, plus replacing all lights with LED (still a/c LED, not DC ones) and getting a much more efficient TV, I'm down to around 10kwh per day. The monthly service charges here are around mid \$20's if I'm not mistaken (for connection and other recurring static charges).  We had the highest power rates in the country, at around \$0.37 cents a kwh on Oahu (where I live) last summer, and I think \$0.45? ish on the neighbor islands. Or was, when gas was high last summer. Its dropped since and is a tad below \$0.30kwh right now. My monthly bill is roughly \$100 but gas is cheap now, my bill was \$250/month at its peak.  Solar penetration is creeping along in the general market and eventually my local utility will have to start charging for daytime banking of excess PV generation, they are already squawking that they don't make enough off the rest of us without grid tied PV; net metering was a GREAT idea until lots of people tried to get it; they abolished it here about a year ago citing that it made their grid "unstable."

My reasons for getting off the grid are personal, and I realize my sentiments will cost me, but I don't mind that much, I hate the local utility that much. I know them from personal and professional interaction and I'm constantly amazed at the waste they and their parent company exhibit, and the callous behaviour of their corporate leadership and personnel in general. Their monopoly must be made to end.  With cheap PV, utilities around the country are all quaking in their shoes.  The only thing stopping more independence is cheap, safe, long term storage solutions (batteries), which has always been the big stumbling block. OK, stepping off my soapbox.

Walt

PS: there is a possibility for propane for cooking and water heating, but I want to give the techluck gadget a go first and see how well it runs and what kind of temps the system produces. Personally, I think its too good to be true, but it just came in the mail yesterday and I already have the spare PV panels, so I'll put the system together and see how it performs before looking at alternatives. For cooking, the hotplate is unbelievably good... I also practice not using it at the max setting, by 'dialing it in' with a kill o watt meter, trying to keep it near 700-800w so it doesn't burden the batteries (its still on grid).  And yes, I've thought of the genny noise and have plans to build a quiet box to enclose them, even though they are already very quiet (just a tad louder than an eu2000i).  Even so, I don't plan on using them past 9pm and never before 7am, my neighbors are nice and I'd like to keep 'em that way.
• Solar Expert Posts: 117 ✭✭✭✭
zoneblue said:
In other words L1 and L2 are in phase.
I believe L1 and L2 are 180 degrees out of phase with one another, which is how you get 240 VAC.

Rancher
• Solar Expert Posts: 5,183 ✭✭✭✭
For your DHW, why not use evacuated tubes for that?  dedicated to your use of hot water and does not need any fancy use of special electric circuitry?

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
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Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
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Hi Westbranch. I'd had plans initially to make my own hot water panels (using small copper tubing and pressing aluminum plates around them to make a simple array), then found the military has turnkey panels with very little (around 1 year) use on them of very high quality for very cheap, so tried to get a couple of those; but someone else has been buying up the whole lots as they come up for sale and I can't get my order in . But, I've since found other problems with that type of hardwired solar hot water... my roof is composite shingles and the manufacturer is now defunct because of a design flaw, these shingles swell and/or are too brittle. I've been lucky so far but that is no guarantee of success. But if a roofer breaks one while up there walking around on them, I cannot get replacement shingles. The only alternative will be to re-roof entirely, so NO ONE will touch these types of roofs or do an install on them.  Even if I could find a contractor willing to gamble, I am not.  Which is why my PV array is in my backyard and the wiring run so long, I have to put the poor things on the ground as the roof is untouchable. I guess I still COULD do a vacuum tube or 'normal' hot water  panels instead of a PV hybrid panel system, but the water lines would be ungodly long.
• Solar Expert Posts: 5,183 ✭✭✭✭
you can mount them on a vertical wall or the ground too...

https://www.wsetech.com/Solar Water Heating Webinar.pdf

pics about page 19 or so

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
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That is fascinating stuff! really neat reading.

BUT (didn't you know there was one coming?) I have to deal with a neighborhood board. They don't like it when you even park rubber slippers (cmon, this is Hawaii!) in front your door sometimes. They will never allow me to park a set of these on the ground or against the side of the house.  They aren't as restrictive as some (a friend of mine in a neighboring community had to erect a 'house' for his 19' boat on a trailer as everything outside had to be 'roofed' to community standards... he spent in excess of \$40k for that). There should be a rule that board members must be gearheads or plumbers or electricians part time, that would ensure all kinds of crazy stuff in people's yards.

• Solar Expert Posts: 5,183 ✭✭✭✭

or Better yet Icelandic Trolls  http://www.iceland.is/the-big-picture/news/celebrating-christmas-with-13-trolls/7916/

KID #51B  4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
• Solar Expert Posts: 117 ✭✭✭✭
kaipo_boy said:I have to deal with a neighborhood board. They don't like it when you even park rubber slippers (cmon, this is Hawaii!) in front your door sometimes. They will never allow me to park a set of these on the ground or against the side of the house.  They aren't as restrictive as some (a friend of mine in a neighboring community had to erect a 'house' for his 19' boat on a trailer as everything outside had to be 'roofed' to community standards...

Check on your State laws, I know in AZ almost every thing Solar is legal, i.e. no HOA can touch it.

Rancher
• Solar Expert Posts: 2,392 ✭✭✭✭
kaipo_boy said:I have to deal with a neighborhood board. They don't like it when you even park rubber slippers (cmon, this is Hawaii!) in front your door sometimes. They will never allow me to park a set of these on the ground or against the side of the house.  They aren't as restrictive as some (a friend of mine in a neighboring community had to erect a 'house' for his 19' boat on a trailer as everything outside had to be 'roofed' to community standards...

Check on your State laws, I know in AZ almost every thing Solar is legal, i.e. no HOA can touch it.

Rancher
Absolutely true!  I had to through that in my HOA's face with a threat to lawyer up.  If they loose they have to pay the lawyer to boot, so most just run away from solar issues as long as you have a permit.
• Registered Users Posts: 342 ✭✭✭
edited April 2016 #20
kaipo,      As has been suggested on this thread wouldn't it be more reliable, cost effective, and simpler to simply get a grid tie inverter like a radian or conext with a subpanel.      Using a subpanel which currently runs 120/240v with a flip if the breaker in the main house box I can disconnect all grid power from the curcuits in the subpanel, and since the subpanel powers 90% of the house's original wiring it's much less expensive than running a 2nd set of wiring throughout the house.

With my fairly standard setup I can run 100% on solar, 97% solar and 3% grid power (allows the grid to back things up automatically if the batteries get too low), or 100%  grid power in case the solar system has a major problem.       It allows me to be solar powered with grid backup at the flip of a breaker.

No 120v hotplate only cooking, no major whole house rewiring, and the grid as a backup.     And if you ever sell the house instead of a large financial cost for the new buyers to be on the grid there is no cost, just flip the switch in your already existing main breaker box.

Yep, you'll need to consider paying an electrician about \$1800 to swap most of the wires currently being fed from your main house panel to a subpanel which is fed by your inverter along with the cost of a grid tie inverter but it's a fairly standard setup.        I completely built my solar system but paid an electrician to wire the sub panel because I wanted to keep my home insurance policy but the subpanel wasn't overly complicated.

As for the hot water heater while there are several options I installed a tankless propane heater.

Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

21 SW280 panels on Schletter ground mount

48v Rolls 6CS 27P

• Solar Expert Posts: 143 ✭✭

Thanks Foolami, you are absolutely right, it would be cheaper and much easier to do a grid tied inverter... but in Hawaii I don't think they are even approving the permits anymore, or if they are, it is at a much reduced rate (no more net metering; have you seen Dave Angelino's posts?), I'm so disgusted with our electric company that I want to get rid of the grid entirely.  Here is something from the local news about American Savings, which is another branch of the company that owns Hawaiian Electric: