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back-fed breaker and generator interconnect

Seven-Delta-FortyOne

Goin’ Down In Flames........
Location
Humboldt
Occupation
EC and GC
When you say wire conductors are you talking about a the factory installed conductors between the meter and the main in a panel that has the meter integrated into the panel AKA a 'trailer panel'? You removing the factory service conductors in a panel like this: ?
View attachment 2572106


Negative. Those ones have the bars on the load side of the breaker. I pull those and replace with conductors to the ATS. I’m not the only one who does them that way either. Dozens and dozens around here like that.

The ones I’m talking about are the kind that have a wire conductor to a backfed breaker.

I will pull those, and extend them to the ATS, then run the conductors from the ATS back to the backfed breaker.

Again, I’m not the only EC doing that, and the inspectors all sign off on that.

Perhaps because it’s a very rural area that loses power for sometimes weeks on end, and regularly has all highways in and out of the county blocked by either landslides, flooding, or wildfires, most people are more concerned with getting a system that is safe and functional, even if it might be unconventional.

Im still not entirely convinced that intercepting the conductors between the meter and the MCB is “modifying listed equipment”. Otherwise there would be virtually no situation where an SE-Rated ATS is needed.
 

gene6

Senior Member
Location
NY
Occupation
Electrician
Those ones have the bars on the load side of the breaker. I pull those and replace with conductors to the ATS.
Am I getting this right, in California, the home of regulation, you can remove the busbars of a UL listed meter/main and add lugs and your own unfused service conductors out to an ATS then feed back in to the main breaker?
 

gene6

Senior Member
Location
NY
Occupation
Electrician
Easiest solution would be to tap the mains and do a supply side solar interconnection, that is islanded with the grid when the grid goes down, leaving the generator alone to power the loads in a grid outage.
You here in the news about these power outages lasting weeks due to weather, wild fires and what have you. Now your saying if these people spend 30k on a solar system they should make sure they can not in any way use solar panels when the power goes out?
If I spent 30k on a solar system it better work when the grid goes down, I could care less whats easy for the solar company.
 

Seven-Delta-FortyOne

Goin’ Down In Flames........
Location
Humboldt
Occupation
EC and GC
Am I getting this right, in California, the home of regulation, you can remove the busbars of a UL listed meter/main and add lugs and your own unfused service conductors out to an ATS then feed back in to the main breaker?

The load side of an MCB is not “unfused”, if what you mean by that is “lacking overcurrent protection“.

Here is a pic of one I bid the other day.

IMG_5895.png

Yes, we will remove those two bars below the MCB, attach terminals to conductors, and run them to an ATS.

Then out of the ATS back to the panel, and terminals to the bus holding the breakers. 👍

Do you install a lot of standby generators? If so, are you saying that for every one you do, you will do a panel changeout for a panel that has a main with no distribution and factory feedthrough lugs?

Im not saying there is anything wrong with that, I'm just surprised if that is how generators are installed everywhere but here.

Im also a bit bewildered as to why manufacturers are manufacturing SE-Rated ATS, if no one anywhere but me is doing line side taps? (Separate issue I know).
 

Seven-Delta-FortyOne

Goin’ Down In Flames........
Location
Humboldt
Occupation
EC and GC
This is hands down my favorite panel, when I have a generator. 👍

IMG_5896.jpeg


IMG_5897.jpeg

I can use the breaker slots if there is a load that they absolutely do not want powered from the generator, like a hot tub or outbuilding, I can pull the feed from the lugs, run a wires to the ATS, and then back to feed whatever sub panels. So easy it’s like taking candy from a baby.

Very few of these panels in use though. I keep a couple in the shop just in case.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
You here in the news about these power outages lasting weeks due to weather, wild fires and what have you. Now your saying if these people spend 30k on a solar system they should make sure they can not in any way use solar panels when the power goes out?
If I spent 30k on a solar system it better work when the grid goes down, I could care less whats easy for the solar company.
It has nothing to do with making things easy for the solar company. The job of a straight grid tied PV system is to offset your electric bill with locally produced energy - no more, no less. When the grid goes down, it shuts off, by law, by UL standards, and (more to the point), physics. If you want a PV system that will power your entire home sustainably during a long power outage, it can be done but it is going to cost you a whole lot more than $30k - like double that or more.

The point of making sure that that a simple grid tied PV system cannot remain connected to the house panel and producing when the panel is switched to generator power is to prevent the PV system from backfeeding and severely damaging the generator, leaving the home with no power at all.
 

gene6

Senior Member
Location
NY
Occupation
Electrician
The job of a straight grid tied PV system is to offset your electric bill with locally produced energy - no more, no less. When the grid goes down, it shuts off, by law, by UL standards, and (more to the point), physics. If you want a PV system that will power your entire home sustainably during a long power outage, it can be done but it is going to cost you a whole lot more than $30
Fair enough, but I as a consumer would never want such a system.
 

gene6

Senior Member
Location
NY
Occupation
Electrician
Exactly. 👍

Are you saying that you would consider that a violation?
Not me, I am not an inspector but yeah that would never fly in NY even in the booon docks upstate, as service equipment cant be modified like that. Thats cool you can do that out in CA though.
When we do a generator install there is typically a meter then ATS acts as main, then a feeder to what was the main panel in a basement like so; The SE cable to the basement gets replaced with a 4-wire SER, the main breaker in the the basement just becomes a feeder main, ground and neutrals are separated in the basement panel. Grounding electrode system moves to the ATS.
 

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RustyShackleford

Senior Member
Location
NC
Occupation
electrical engineer
If you want a PV system that will power your entire home sustainably during a long power outage, it can be done but it is going to cost you a whole lot more than $30k - like double that or more.
There is a line of solar inverters, SMA Sunny Boy, that will provide you with about 1000-1500 watts of 120vac power when the grid is shut down (and the sun is shining). I wouldn't call that "sustainably during a long power outage" but it's better than nothing. Can cerainly power a frigde, some lights, modem. Or put some juice in your EV, if you have it rigged to be able to put some juice into your panel.
 

gene6

Senior Member
Location
NY
Occupation
Electrician
There is a line of solar inverters, SMA Sunny Boy, that will provide you with about 1000-1500 watts of 120vac power when the grid is shut down (and the sun is shining). I wouldn't call that "sustainably during a long power outage" but it's better than nothing. Can cerainly power a frigde, some lights, modem. Or put some juice in your EV, if you have it rigged to be able to put some juice into your panel.
That would be perfect
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
That would be perfect
OK, but understand, 1000 -1500W isn't all that much, and it depends on the DC part of the system generating at least that much power. If you put more demand on the system than it can supply, it will shut down. Yes, you can use it to charge your phone and run a refrigerator for a while during the day, but it is limited emergency power from a single outlet connected directly to the inverter and it won't power any lights at night. Backup power to your home is another thing entirely.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Thats interesting, so you keep the main as the main, View attachment 2572112 so your end result looks like this?
I think that might be a wiring space violation. I could also cite 110.3(B) or at least make a big fuss about whether the lugs are suitable and the crimping done properly. Or whether that shrink-tube and tape is gonna stand the test of time or eventually give way to a huge short. If we did that sort of thing routinely here in the Bay Area we would probably at the least earn enough distrust from some inspectors that they'd look for any other reason to fail us. My point here isn't so much to cry 'code violation' and declare it needs to be ripped out; the particular photo posted here it looks like it's done professionally. But I've seen similar photos where the terminations were compete hack work and probably dangerous. Also subject to Dunning-Kruger issues: some guy has seen it done once and thinks he knows everything and doesn't use the right crimp tool and does bad terminations. One could argue it's a slippery slope; at the very least the details matter and it cannot be done on any given meter/main. And I wouldn't consider PG&E project managers to be qualified to discriminate between those details.

I can see how in a rural area with different demands, especially if the inspectors have seen enough of a contractor's work to know their level of professionalism, there could be a different attitude than in an urban area. And I'm more worried about the contractors who don't get their work inspected at all.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
You here in the news about these power outages lasting weeks due to weather, wild fires and what have you. Now your saying if these people spend 30k on a solar system they should make sure they can not in any way use solar panels when the power goes out?
If I spent 30k on a solar system it better work when the grid goes down, I could care less whats easy for the solar company.
The simple answer here is add battery backup and an MID to the solar system. Once you say that, the actual details get more complicated. People would spend 30k on a solar system to save $5000 a year on electric bills. You have to explain to them that backup power is an additional luxury that doesn't pay for itself (same as a generator).
 
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