Due to a misreading of the electrical code, many jurisdictions in the Run on Sun service area - and yeah, we are talking about you, LA County - balked at allowing homeowners to install solar if they were connecting to a center-fed panel. This has resulted in costly, and unnecessary service panel upgrades, and even prevented some homeowners from adding solar at all!
Well good news - LA County has finally gotten with the program and agreed to interpret the code consistent with the intent of the code's authors. Here's the scoop....
We have written about this problem at some length before - you can see those articles about solar and center-fed panels here. The confusion arose because the code calls for connecting the solar breaker to the opposite side of the bus from the main breaker. Since on a center-fed panel the main breaker is in the middle of the bus, there was no "opposite side" to mount the solar breaker, according to that tortured interpretation. (In the photo on the right, you can see the large, main breaker in the center, with load breakers above and below it.)
To get around this problem in jurisdictions that held to that view of the code's intent, various approaches were brought forward, all of them more dangerous and/or complicated than simply putting a solar breaker at one end of the bus.
For example, a couple of years ago, San Diego Gas & Electric introduced an adapter ring to fit between the meter socket and the service meter. Soon thereafter, SCE adopted a similar solution, and that became our "go-to approach" for center-fed panels in LA County.
While County would sign-off on the SCE ring (or Generation Meter Adapter, as SCE called it), it was really an awful solution to the problem For one thing, SCE charged the homeowner just under $500 for the install, and their technician had to do the work in full arc-flash protection gear - a testament to the hazard involved. Beyond that temporary risk, the connection now left a pair of terminals in the solar disconnect with no over-current protection between them and the power pole transformer. Short that connection out, and nothing would stop that current from flowing until the wires melted!
A better solution was recently brought to market in the form of the B3-Bypass breaker which we wrote about last Fall. The B3 fits into center-fed panels and provides a much safer way to interconnect solar than the GMA ring. But guess what? Despite it having passed UL certification, LA County will not accept it, as we learned when we attempted to submit plans calling for the installation of the B3!
So, back to square one? Well not quite. While on the phone with County's plan checker, I remembered that a code amendment had been passed effective a year ago January, that clarified the intent of the code when it comes to center-fed panels. We had cited this amendment to County last year, only to be told that County had not yet approved the amendment - hence we installed multiple GMA rings with center-fed panels last year.
Here's the language of the amendment:
A connection at either end, but not both ends, of a center-fed panelboard in dwellings shall be permitted where the sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar does not exceed 120 percent of the current rating of the busbar.
This is what we had been saying all along, and the code amendment makes it clear that this is an acceptable thing to do - as well as being cheaper and safer than any of the alternatives.
So, I asked the plan checker, had County gotten any closer to adopting this amendment? "Oh," said the plan checker, "we've been accepting it since January, 2017!"
Sigh. So not true. At least none of the plan checkers that we encountered in 2017 were accepting the amendment. And for that matter, this plan checker did not volunteer the information. Instead, he was about to sign-off on the GMA ring without ever bothering to mention that there was a safer and cheaper way for us to meet the needs of our client! Is it too much to ask that a plan checker point out policy changes of which s/he is aware when discussing plans with a contractor?
Here's the bottom line: If your solar project meets the interconnection requirements set forth in the quoted language above, you do not need to upgrade your panel, and you don't need a GMA ring to attach solar to your center-fed panel in LA County territory. (And if it satisfies LA County, presumably every other jurisdiction should go along as well.)
If you need documentation - either as a homeowner to provide to your solar contractor who is trying to sell you an unwanted service panel upgrade - or as a solar contractor trying to convince a recalcitrant AHJ - here's the link to the California Building Standards Bulletin that approves the amendment, and here is Bill Brooks' write-up explaining the need and justification for the amendment.
Here's the money quote from the latter:
The fact that several thousand center-fed panels in good repair have required replacement over the past two years when, in fact these upgrades are unnecessary, presents a real and unnecessary hazard to the field workers required to perform these replacements. Any time a service equipment replacement is performed on a dwelling, utility service must be interrupted and significant electrical work must be performed to replace the equipment. This exposes the electrical worker to hazards of potentially live conductors and inadvertent errors that could even be fatal. The hazards of these upgrades is appropriate when the existing service equipment is damaged or has outlived its useful safe operating life. Performing these upgrades on perfectly good equipment that is not a safety hazard to the dwelling is an unnecessary risk.
We couldn't agree more!