Az-srp 3 line wire diagram advice/examples?

[icandoitmyself_AZ]

Hello,

i am currently working on a 7.3kw-dc/ 5.52kw-ac, enphase micro-inverter based system, and i am in the Chandler AZ AHJ. While working through the permit process i have bumped up against a rejection from SRP, on the 3 line diagram i have provided them... i will post the current 3 line here. i am very much trying to learn the requirements for the 3 line and the rest of the permit process, so i am trying to avoid paying a service to do all of the permit work for me.. and save a few bucks as well...

i was wondering if someone from srp/chandler territory would be willing to send/share their "accepted" 3 line diagram, in my research i really have not seen any good examples of a micro-inverter 3 line diagram,(with name and address redacted of course). i believe that would be all i need to make the necessary updates for this to be accepted.

thanks!

[azdave]

SRP next door to you in Gilbert...

Wish I could help but I chose to keep it simple and not put micros on my roof in 2014. Simple string inverter is all I have.

[Markyrocks69]

Did they not give you a reason for the rejection?

I'm not an electrical professional but the only issue that sticks out to me is 10 gauge 75 degree wire base amps should be 35. You have that listed at the end of the row in your diagram. Based on a quick search of how to derate a conductor I believe that you have to start with the amps based on the ampacity of the conductor and the temp rating of the wire.

I found this calculator it seems to backup what I'm saying.

http://www.electrician2.com/calculators/wireocpd_ver_1_reverse.html

It also appears that your using the temp correction numbers for 90 degree wire vs 75 degree wire, the correction is different depending on the temp rating of the wire at the same ambient temperature. Hope this helps

[SunEagle]

What specifically did SRP not like concerning your wiring diagram?

[ButchDeal]

I would guess that part of the issue is that you are not showing the micros wired in parallel on the AC side ...and/or all of the micros.

You don't have to show them all but just a few on each with a note that 1-x are similar to ...

[icandoitmyself_AZ]

thanks for the helpful suggestions!

SunEagle,
unfortunately, they just said "rejected" and please resubmit after making necessary changes to the 3 line diagram...

ButchDeal,
good suggestion, although my confusion, is that is it not painfully clear that the micros are 2 strings in parallel? but its entirely possible this is what i am missing, and needing to make the 3 line painfully clear...

[ButchDeal]

ButchDeal,
good suggestion, although my confusion, is that is it not painfully clear that the micros are 2 strings in parallel? but its entirely possible this is what i am missing, and needing to make the 3 line painfully clear...

They don't like to leave anything to be assumed.
Yours shows 1 micro on each string by itself and then 2 more just sitting there only connected by ground wire.
you should also include the manufacture spec sheet for the micros if you didn't already.

[Markyrocks69]

Idk if you've had a chance to look at that calculator I posted but from what I got 10 awg 75 degree wire (35amp) derated for 43 degrees 35amp x .82= 28.7 which is greater than your max output of 28.75 so I'd assume that's a violation. And I believe if you have 4 or more conductors in a single conduit you may have to derate even further. Again I'm not an electrician but the calculator backs up the first bit of math. I love math btw

[icandoitmyself_AZ]

Idk if you've had a chance to look at that calculator I posted but from what I got 10 awg 75 degree wire (35amp) de-rated for 43 degrees 35amp x .82= 28.7 which is greater than your max output of 28.75 so I'd assume that's a violation. And I believe if you have 4 or more conductors in a single conduit you may have to de-rate even further. Again I'm not an electrician but the calculator backs up the first bit of math. I love math btw

i really do not think it is this... even if using your calculator, which is a neat little handy tool btw. taking my configuration, using 2 separate branches, each with a max current of 15A and 13.75A respectively, which is much less << than the de-rated amp capacity of 27.84. which is then combined at the combiner box to a total single branch of 28.75A when de-rated using standard temp correction factor is still << 34.8 de-rated amperage factor.. perhaps i need to standardize the "temp rating" but, in any case i believe i have more than enough cable capacity.

i still would appreciate someone posting a 3 line diagram that has been approved by SRP... that IMHP would help a great deal to clarify the "style" that they are looking for on a drawing.

thanks again everyone!

[Markyrocks69]

i really do not think it is this... even if using your calculator, which is a neat little handy tool btw. taking my configuration, using 2 separate branches, each with a max current of 15A and 13.75A respectively, which is much less << than the de-rated amp capacity of 27.84. which is then combined at the combiner box to a total single branch of 28.75A when de-rated using standard temp correction factor is still << 34.8 de-rated amperage factor.. perhaps i need to standardize the "temp rating" but, in any case i believe i have more than enough cable capacity.

i still would appreciate someone posting a 3 line diagram that has been approved by SRP... that IMHP would help a great deal to clarify the "style" that they are looking for on a drawing.

thanks again everyone!

the point you're missing is your takeing 35 amp wire and derating from 40amps down. A 10 gauge 75 degree wire is only rated for 35 amps. So in what world would we then say I'm going to take 40 amps and derate from there? The whole point of the derate is bc the wire as it exists can only handle x temperature and y amps. Amps equals more heat, the point of the derate is so that the wire stays under a certain temperature under max load. Idk how else to explain this.


I'll even show your math. 40 Amps x .87= 34.8amps.... this would be true if this wire were rated for 90 degrees you have it listed as 75 degree wire.
75 degree wire math is 35 amps x .82 which is 28.7 which is less that the max output.

I'd honestly like to know how you came to your original conclusions. Can you show that work?

[icandoitmyself_AZ]

fair point, i should be more consistent in the original drawing.

the correction is that i am using 90C wire in all locations.. then the correction factors all make sense...

[Markyrocks69]

fair point, i should be more consistent in the original drawing.

the correction is that i am using 90C wire in all locations.. then the correction factors all make sense...

Fantastic!! Omg you had me worried there for a minute. I thought I may have found something else but upon further investigation It looks good to me. Does the poco have a webpage that goes over the permitting process ect? I'd like to take a look at that if available.

[SunEagle]

fair point, i should be more consistent in the original drawing.

the correction is that i am using 90C wire in all locations.. then the correction factors all make sense...

The only way to get a wire rated for 90C is to also use all terminations that have at least a 90C value. Since most terminals are only rated at 75C you can only use the amp rating for wire at that temperature. That may be one reason for the rejection.

Maybe going with larger wire with a higher amp rating may help your system being accepted.

[icandoitmyself_AZ]

Quick update, i did receive additional information from the Utility, and primarily, i was missing some note callouts, for labeling on various equipment pieces. and the AC disconnect, and the Solar Meter need to be swapped. other then that they mentioned everything as fine.

as an aside, i will be posting a fully "blessed" 3 line diagram once i am through the full permitting process, for anyone else out there who has questions about formatting or general guidelines in the AZ SRP territory.

[SunEagle]

Quick update, i did receive additional information from the Utility, and primarily, i was missing some note callouts, for labeling on various equipment pieces. and the AC disconnect, and the Solar Meter need to be swapped. other then that they mentioned everything as fine.

as an aside, i will be posting a fully "blessed" 3 line diagram once i am through the full permitting process, for anyone else out there who has questions about formatting or general guidelines in the AZ SRP territory.

Great. I find it hard to determine a system rejection without knowing a reason. We could have spent many days poking holes in your 3 line diagram without hitting the reason for it not passing.