Plug In

Thomas · February 2012

Why did uncle sam restrict the sale of these inverters to plug in, does everyone truly believe that they would manufacture/sell with a plug instead of a terminal block? Why did Uncle Sam do this?

icarus · February 2012

Re: Plug In

It is not uncle Sam! It is the safety testing agencies like UL ( which is funded by the insurance companies to some extent) as well as widely accepted electrical code agencies like NEC. Fundamentally, plug in inverters are not permitted in grid tie installations for a couple of reasons. The first is that they conflict with the NEC on a number of different levels, primarily that there is the potential to overload branch circuits without the installer knowing it. The second is by allowing plug in inverts, it would allow users to potentially back feed the utility, potentially putting linemen at risk. This potential problem is exacerbated by the utility not having knowledge of such potential, since plug in inverters could be plugged in with out proper electrical permits and inspections.

Tony

Thomas · February 2012

Re: Plug In

I do not think the plug in manufacturer particurally give a hoot about what anyone says if that person or agency can not stop them from marketing in the US. Uncle Sam is the only entity that can do that, in collaboration with others like UL and NEC probobly. I revert to my original question why are these grid tie inverters comanies forced to sell with the plug in? They are capable of the same thing with or without the strange access means. I do not think that the companies did it to themselves. I do not think the market did it to them either. I looked for months for one with a terminal block...as far as being a safety threat to linemen or anything else, thats pure hogwash, even at the thousands of watts thay can be rated to, it is no match for the thousands of volts in the line, as a matter of fact I believe they mingle nicely together. Again if the instructions are followed harm to onesself or property can be avoided.

solarvic · February 2012

Re: Plug In

How long are you going to beat this subject? Many have told you that it isn,t legal to use.

BB. · February 2012

Re: Plug In

Thomas wrote: »

I do not think the plug in manufacturer particurally give a hoot about what anyone says if that person or agency can not stop them from marketing in the US. Uncle Sam is the only entity that can do that, in collaboration with others like UL and NEC probobly. I revert to my original question why are these grid tie inverters comanies forced to sell with the plug in? They are capable of the same thing with or without the strange access means. I do not think that the companies did it to themselves. I do not think the market did it to them either. I looked for months for one with a terminal block...as far as being a safety threat to linemen or anything else, thats pure hogwash, even at the thousands of watts thay can be rated to, it is no match for the thousands of volts in the line, as a matter of fact I believe they mingle nicely together. Again if the instructions are followed harm to onesself or property can be avoided.

Actually, it is perfectly legal to import and sell "Plug&Play" inverters in the US. Installing them on regulated (Utility Power) without permits (or with hardware that does not meet NEC/Building Code Requirements) is not.

Would a "modern" Grid Tied Inverter backfeed a utility line. No--probably not. And while you are correct that these are small units and not likely to drive enough power into utility lines to cause damage. It is not impossible. Remember, there are homes connected to the same drop that can have their wiring energized. And you have a 12,000 volt+ transformer that could be energized too. Of course, linemen are supposed to treat all lines as hot and insulate/ground those they are working on.

But--that is how code works. If everyone follows the code requirements, then there should be "no surprises".

The issue of "Plug&Play" at the home level is real. There are issues with 15 amp breaker + 12 amps of GT power adding together to have 27 amps on a 14 awg circuit rated for 15 amp maximum. Somebody could plug in a couple space heaters on a shared outlet and pull ~27 amps--and start a fire at the outlet/pigtail.

If you want to get into alternate wiring schemes... There is the Double Feed (forgot the name) for Britain. They have a 13 amp breaker feeding each end of the breach circuit--So you have two 13 amp breakers feeding the branch. Turns out, if there is a short, the "left" wire will carry 13 amps (at 230 VAC) maximum (pop breaker) and the "right" will only carry 13 amps max before popping its breaker. However--that requires each lamp plug to have a 13 amp fuse in the plug itself--that way the lamp/cordset cannot draw more than 13 amps either.

I could see something like that, possibly working, with a plug and play system (still not sure it is "safe" with a GT inverter system plugged in a general circuit--can exceed 13 amps with certain types of failures--a no no)... But that is not what we have here in North America.

There are lots of issues with "faults" causing failures and fires with distributed power systems... It is actually quite complex and not always easy to resolve without throwing more hardware (or in this case dedicated branch circuits) at the problem.

We have kicked the question around our forum (and its sounds like others have too) and there appears to be no way to make a "safe" plug and play GT inverter system.

And that is ignoring the issues of panel mounting (may require a structural engineer to sign off), permanently installed equipment must be hard grounded for safety (bolted up green wires), and access issues (wiring in metal conduit to enter the home; requiring fencing to prevent people from accessing panels/wiring, etc.).

Believe me, we are not picking on plug and play people because we are "hardwired GTI" system fanboys.

-Bill

Slappy · February 2012

Re: Plug In

"as far as being a safety threat to linemen or anything else, thats pure hogwash, even at the thousands of watts thay can be rated to, it is no match for the thousands of volts in the line"

transformer that feeds your house is a step down. so you can get 120-0-120 volts at your meter. if you back feed the transformer it will step up the voltage in to the thousands of volts, and then you will fry a lineman. like it has been mentioned, these plug-in stuff, is ILLEGAL and dangerous! does people have/use them....yes. But when something goes wrong, I would not want to be in their shoes.....PERIOD.

Thomas · February 2012

Re: Plug In

I have absolutely no Idea what you are talking about with the split breaker, all I know from mistake expireince is both in parallell must be the same rating .....

Are 'faults the type of loads I am calling resistive? If so I am trying to lead a 'Faultless life"?! Just great

I thought AWG stndard for households was 12AWG not 14AWG.

That does sound dangerous,What I heard is one outlet handles 7Amps/15amps short(water heater or something..)I dunno about the whole line. My whole house is 10AWG now anyway.

It is a plug and play marketing thing then.
I still think that it would have been easier and more lucrative for thewm to have been able to market otherwise.
Aluminum blocks are cheap, the code is readily available to meet, and Asian Electrical Engineers are probobly numerous to design it.

BB. · February 2012

Re: Plug In

Thomas wrote: »

I have absolutely no Idea what you are talking about with the split breaker, all I know from mistake experience is both in parallel must be the same rating .....

Thomas, trying to careful, clear, and polite. You are mixing so many terms and issues that it is impossible to answer your questions as asked.

Are 'faults the type of loads I am calling resistive? If so I am trying to lead a 'Faultless life"?! Just great

Faults are "faults"... If short circuit, you get too many amps and pop the breaker(s)/fuse(s). If you plug in too many loads, too much current. If a wire or insulation fails and shorts to ground, another fault.

There are faults (connections) to water/grounded metal. A GFI (Ground Fault Interrupting) breaker should open before the current gets high enough to kill you.

There are Arc Faults (arc to ground, arc from wire to wire, etc.) which create local intense heat--but may not exceed the circuit current rating. An Arc Fault Interrupting Breaker will monitor the frequency spectrum and energy--figure out there is an Arc, then turn off the breaker.

Fault is just a generic term.

I thought AWG stndard for households was 12AWG not 14AWG.

City I grew up in, changed from 14 AWG to 12 AWG wiring minimum for all new construction. Very expensive and a pain to wire things up like thee way switches for hall lights in a standard junction box. I think many cities also require 12 AWG minimum for commercial construction.

10 AWG is pretty heavy stuff... You can certainly put a 15 amp breaker on 10 AWG wiring... However, you cannot put a 30 amp breaker on 10 AWG wire and use standard 15/20 Amp 120 VAC outlets in the home.

It is a plug and play marketing thing then.
I still think that it would have been easier and more lucrative for them to have been able to market otherwise.

Yes, easier for them to sell... But leaves customers with the impression that doing things not to code is safe and acceptable. It is not.

Aluminum blocks are cheap, the code is readily available to meet, and Asian Electrical Engineers are probobly numerous to design it.

I do not know where it is legal or safe to use aluminum bus blocks for any wiring solutions. Aluminum forms an insulating oxide on its surface within seconds or minutes of being exposed to air. Aluminum wiring fires are a huge issue today and Aluminum is no longer allowed (I think). And I would never do any construction with aluminum wire even if I got it for free.

The Fire Dangers of Aluminum Wiring - New York Times

-Bill

icarus · February 2012

Re: Plug In

As has been suggested before,, I suggest you get, read, and understand some basic electricity. I suggest you read "wiring simplified" as well!

As for #12 vs #14 wire. All wire is sized (or should be sized) for the load, and therefor needs to be fuse/breaker protected for that wire size. In general terms, #14 wire is rated for 15 amps, and needs to be fused no bigger than 15 amps. That 15 amps could provide ~1800 watts of power at 120vac.

#12 wire is rated for 20 amps (or 2400 watts at 120 vac) and can be fused at 20 amps. There is no "crime" in under fusing a wire, but there is real danger in over fusing any run of wire.

Houses can (and routinely are) wired with a mix of # 12 and # 14. 12 for the 20 amp kitchen circuits where loads tend to be large, and 14 for routine lighting/outlet circuits. Wiring your house with # 10 is a waste of money, as routine outlets are only rated for 15 amp loads and 20 amp carry through, so you should never have more than 2400 watts on the circuit. The only advantage of larger wire in this case, is a slightly smaller voltage drop.

I also need to reenforce the danger of back feeding the utility. If you back feed the line transformer, 120 vac, it will step that voltage back up to what ever the primary voltage of the utility (~14,400 vac) So now up on the pole (and all down the line) there is the potential for your PV to produce enough high voltage at enough current to kill a lineman. While that isn't likely it is possible. Additionally, you could potentially feed your neighbours load, causing trouble if he thinks the power is dead.

But to reenforce the point,, read some books, begin to understand enough about electricity to ask relevant questions.

Tony

Thomas · February 2012

Re: Plug In

This all sounds familiar, and that is entirely possible. Thank you,
Aluminum was mentioned as a terminal block, like in breaker boxes and bus bars.
As far as spreading electricity around dangerously free for the power company to charge and not have created...free electricity for the power company too.

mike95490 · February 2012

Re: Plug In

This is an aluminum terminal block. It is tin plated, and very beefy. It is also expensive, and must live in an enclosure
Attachment not found.
I've used these to splice and also breakout, feeds from #6 aluminum that travel over my ranch. They are UL listed.
http://www.elecdirect.com/catalog/8063c3d2-b684-4c58-b7f1-c885828651cc.aspx

Thomas · February 2012

Re: Plug In

I think I would have paid the price for it at the time that is what it was missing. I am using only #8 for short runs
My juncture is in a Double gang box all nice and sealed in an enclosure itelf, what are the dimensions of it?

Photowhit · February 2012

Re: Plug In

icarus wrote: »

...Wiring your house with # 10 is a waste of money, as routine outlets are only rated for 15 amp loads and 20 amp carry through, so you should never have more than 2400 watts on the circuit. The only advantage of larger wire in this case, is a slightly smaller voltage drop.

In a time when solar panels were expensive and copper a lot cheaper, it was common to recomend heavier wire, to reduce losses in resistance. My cabin is wired with 10 gauge, with no regrets as to the small additional expense, I had purchased 250' of 10 gauge 12years ago(now) for less than 50' sells for now.

I believe most homes have aluminum wire coming in from the PC, FWIW. I'd be glad to do a scratch test, but I believe the 0000 blocks in my power center are aluminum rather than tinned copper. Not tryingto feed the fire just suggesting aluminum has it's places.

Justin Chew · February 2012

Re: Plug In

Thomas wrote: »

Why did uncle sam restrict the sale of these inverters to plug in, does everyone truly believe that they would manufacture/sell with a plug instead of a terminal block? Why did Uncle Sam do this?

Which inverters is Thomas talking about, I don't see where it says? Oh no, another plug in GT debate, i'm staying outta this one, you're welcome lol :roll:

Plug In

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