Solar Calc's 400A. Main Buss w/ Main Lugs to Two 200A. Main Breakers

[sreagle]

My first Solar Install,
the Main Panel is 400A. note; no 400A. Disconect, Single Meter Two 200A. Services, One to Home and One Spare/ not being used
Since there is no 400A. OCPD and only 400A. Main Buss going to Two 200A. Main Breakers
The first 200A. Main is a Lug Only wired direct to Home Panel
The second 200A. Main has a Buss for OCPD

With that said is it 400 x 1.2 = 480 - 400 = 80A. for Solar,
Or 200 x 1.2 = 240 - 200 = 40A. for Solar ???

Please be patience never done this before, I may have some follow up questions
I am in Riverside County Calif if anyone intrested.
tnx Steven

 

[GoldDigger]

If the bus in the panel is rated 400A, that is where you start.
The you either subtract 200 from 480 if only one 200 breaker is actually fed or 400A if both inputs are live.
Make sure that no other breaker spaces fall between the two mains and the PV backfeed(s).

Tapatalk!

 

[Smart $]

My first Solar Install,
the Main Panel is 400A. note; no 400A. Disconect, Single Meter Two 200A. Services, One to Home and One Spare/ not being used
Since there is no 400A. OCPD and only 400A. Main Buss going to Two 200A. Main Breakers
The first 200A. Main is a Lug Only wired direct to Home Panel
The second 200A. Main has a Buss for OCPD

With that said is it 400 x 1.2 = 480 - 400 = 80A. for Solar,
Or 200 x 1.2 = 240 - 200 = 40A. for Solar ???

Please be patience never done this before, I may have some follow up questions
I am in Riverside County Calif if anyone intrested.
tnx Steven

Depends on where you tap in...

If before 200A ocpds, it's up to the service conductors rating or 400A bus rating, whichever is the lesser of the two.

If after a 200A ocpd, 40A as you calculated.

The 400A panel is MLO. Each breaker is a Service Disconnecting Means. The busing is considered service conductors.

Are there additional spaces for breakers?

 

[Smart $]

If after a 200A ocpd, 40A as you calculated.

Actually, it's based on the the feeder rating not OCPD rating. Feeder rating could be >, =, or < than OCPD rating.

 

[sreagle]

Actually, it's based on the the feeder rating not OCPD rating. Feeder rating could be >, =, or < than OCPD rating.

I got the exact spec's of the Panel
Overhead Feed Service 400A. maybe less, I might have to check with Edison as it turns out The Panel is Rated at 320A. 120/240V.
Single Meter/ with Two 200A. Main Breakers, One feeds the Home and No Buss, the other 200A. has a Buss for other Breakers, Only
has One 15A feeding a Dusk to Dawn Light nothing else on it.
The Panel of course is Existing and the overhead feeders I am assuming meet or exceed the 320A. for Service

The County of Riverside Planner says it's a 200A. Panel
320 x 1.2 = 384 - 200 = 184 Amps for Solar or,
200 x 1.2 = 240 - 200 = up to 40 Amps for Solar

 

[Smart $]

I got the exact spec's of the Panel
Overhead Feed Service 400A. maybe less, I might have to check with Edison as it turns out The Panel is Rated at 320A. 120/240V.
Single Meter/ with Two 200A. Main Breakers, One feeds the Home and No Buss, the other 200A. has a Buss for other Breakers, Only
has One 15A feeding a Dusk to Dawn Light nothing else on it.
The Panel of course is Existing and the overhead feeders I am assuming meet or exceed the 320A. for Service

The County of Riverside Planner says it's a 200A. Panel
320 x 1.2 = 384 - 200 = 184 Amps for Solar or,
200 x 1.2 = 240 - 200 = up to 40 Amps for Solar

Sounds like you have a meter/main/panel combo. If you tie in using a breaker space of the "panel", you will be limited to 40A solar: 1) combined inverter output ratings [2014 NEC] or 2) combined inverter output breaker ratings [previous NEC Editions].

 

[sreagle]

Sounds like you have a meter/main/panel combo. If you tie in using a breaker space of the "panel", you will be limited to 40A solar: 1) combined inverter output ratings [2014 NEC] or 2) combined inverter output breaker ratings [previous NEC Editions].

Here is a link with the pic of the panel Model M400-UG-APS-LC
Page 16 http://www.milbankworks.com/blog/wp-content/uploads/2013/03/Louisiana-Mississippi_Web_4-13.pdf

I sure apericate all the help here, Not getting any help with the gal at B&S in Riverside County

 

[Smart $]

Here is a link with the pic of the panel Model M400-UG-APS-LC
Page 16 http://www.milbankworks.com/blog/wp-content/uploads/2013/03/Louisiana-Mississippi_Web_4-13.pdf

I sure apericate all the help here, Not getting any help with the gal at B&S in Riverside County

Using an breaker in the panelboard portion, you can go up to 40A.

If you need to go higher than 40A, not sure if you can tie into the bus on the right side of the main breakers by adding lugs. Looks a bit tight for meeting wire bending space. If you can, you'll have to provide a separate PV system disconnect/OCPD, but you would be able to go up to service rating.

 

[Smart $]

Just what size PV system is desired?

 

[sreagle]

Just what size PV system is desired?

was going to be 2 banks of 25A now after what you have informed me and
after talking it over 2 banks of 20A for a 40A system
sure apericate all the help.

One last question i think lol
If the panel would of had a 400A main Service Breaker feeding Two 200A Main Breakers i could use 400x1.2=480-400=80A
Insted I have a 400A Service without a 400A service disconect, But I still have 400A. Service feeders, Mains, etc so the Service
Means Nothing back to 200A, 200x1.2=240-200=40A ???
Just makes no sence to me...

 

[Smart $]

was going to be 2 banks of 25A now after what you have informed me and
after talking it over 2 banks of 20A for a 40A system
sure apericate all the help.

You didn't say what code cycle this is being installed under. If 2011 or earlier, it's 40A of OCPD... which is not less than 125% of inverter output(s) rating. Under 2014 the CMP finally conceded on using output ratings (you can go up to 50A OCPD for a single inverter, possibly higher for multiple inverters).

One last question i think lol
If the panel would of had a 400A main Service Breaker feeding Two 200A Main Breakers i could use 400x1.2=480-400=80A
Insted I have a 400A Service without a 400A service disconect, But I still have 400A. Service feeders, Mains, etc so the Service
Means Nothing back to 200A, 200x1.2=240-200=40A ???
Just makes no sence to me...

That's the rules, whether they make sense or not. The issue has been debated extensively on this forum... so I'll not get into it here to any major degree.

The main concern is where loads allow power to be drawn through two or more OCPD's. Overcurrent could occur with neither OCPD tripping. In the case of line-side connection, the loads are powered through only one source OCPD, limiting overcurrent to the characteristic trip response of that one OCPD.

 

[sreagle]

You didn't say what code cycle this is being installed under. If 2011 or earlier, it's 40A of OCPD... which is not less than 125% of inverter output(s) rating. Under 2014 the CMP finally conceded on using output ratings (you can go up to 50A OCPD for a single inverter, possibly higher for multiple inverters).


That's the rules, whether they make sense or not. The issue has been debated extensively on this forum... so I'll not get into it here to any major degree.

The main concern is where loads allow power to be drawn through two or more OCPD's. Overcurrent could occur with neither OCPD tripping. In the case of line-side connection, the loads are powered through only one source OCPD, limiting overcurrent to the characteristic trip response of that one OCPD.

Here in Calif they use what they call the 2013 Calif El Code it's the 2011 NEC
And the PV system Enphase Micro Inverter M215
Orginaly was going to be One Array of 16 and One Array of 20 total of 36
Now going to 16 each total of 32

 

[sreagle]

400A Main Meter Panel w/ Two 200A Main Breakers feed from Line Side Tap "Panel Calc's

400A Main Meter Panel w/ Two 200A Main Breakers feed from Line Side Tap "Panel Calc's

2013 Calif Electrical Code/ or 2011 NEC
400A Main Meter Panel w/ Two 200A Main Breakers feed from Line Side Tap "Panel Calc's
for referance here is the Panel on PAGE 16 of this link
http://www.milbankworks.com/blog/wp-content/uploads/2013/03/Louisiana-Mississippi_Web_4-13.pdf
So I have a 400A. Metered Panel with two 200A Main Breakers both are Line Side Taped
according to Milbank the Buss is rated at 320A. or so I am assuming by there Info "please see link above"
The First 200A. Main has no Load Side Buss it is a Direct Feed to the House,
The Second 200A. Main feeds a Load Side Buss NOTE: There is only One 15A. Breaker for an Dusk to Dawn Light Fixture on it.
According to the local AHJ Riverside County B&S in southern California I have a 200A. Panel, I am trying to Calc this out for a PV System
Local AHJ says;
I am allowed a 40a. PV System based upon 200x1.2=240-200=40A.
They also say I can derate the One 200A. Breaker to a 150A. Breaker if I supply Load Calc's on the House "I am assuming", which means there saying I have a 200A. Buss
Do I really need to provide Calc's ? On what the 15A Light Fixture that is connected to the side/ Load side buss I am using for the PV System
And How dose a 150A Main help ? Rember Both Mains are Line Side Taped

The PV System is as follows;
Mfg/Model Enphase Micro Inverter mod# M215
each micro inverter is rated at 0.215 kw at 96% efficenty
there are Two Banks "Current Configuration" may have to change
Each Bank there are Currently 18 Panels may have to reduce them to 16 each
18x0.215 kw = 3.87 = 16.125A x 125% = 20.15 A at 240V, I think after talking it over with the home owner that will Change to Two Bankes of 16 Panels x 0.215 kw = 3.44 kw = 14.33A x 125% = 17.91A giving me a 40A 240v cir. to satify B&S

Any Input or Follow up Questions welcomed

 

[Smart $]

...They also say I can derate the One 200A. Breaker to a 150A. Breaker if I supply Load Calc's on the House "I am assuming", which means there saying I have a 200A. Buss
Do I really need to provide Calc's ? On what the 15A Light Fixture that is connected to the side/ Load side buss I am using for the PV System
And How dose a 150A Main help ? Rember Both Mains are Line Side Taped...

They're saying if you decrease the 200A main breaker for the local panel, you can up the PV system rating. The local has a 200A bus. If you replace the 200A main breaker with a 150A, your bus calc' changes to...

200A * 120% = 240A
240A - 150A MCB = 90A PVSB max.

Potential downside is that Milbank may not offer a 150A breaker that swaps out with the 200A. You'll have to check with them.

I don't see how a load calc' for the house panel is pertinent. If the service bus is rated for 320A and the house panel is on a 200A MB, that automatically leaves 120A minimum for the "other side". The only requirement for multiple service OCPD's is that the load not exceed the ampacity of the service conductors.

Exception No. 3: Two to six circuit breakers or sets of
fuses shall be permitted as the overcurrent device to provide
the overload protection. The sum of the ratings of the
circuit breakers or fuses shall be permitted to exceed the
ampacity of the service conductors, provided the calculated
load does not exceed the ampacity of the service
conductors.

 

[sreagle]

They're saying if you decrease the 200A main breaker for the local panel, you can up the PV system rating. The local has a 200A bus. If you replace the 200A main breaker with a 150A, your bus calc' changes to...

200A * 120% = 240A
240A - 150A MCB = 90A PVSB max.

Potential downside is that Milbank may not offer a 150A breaker that swaps out with the 200A. You'll have to check with them.

I don't see how a load calc' for the house panel is pertinent. If the service bus is rated for 320A and the house panel is on a 200A MB, that automatically leaves 120A minimum for the "other side". The only requirement for multiple service OCPD's is that the load not exceed the ampacity of the service conductors.

I Understand that too, but the lady at B&S is stuck on her Opinion that there is only a 200A Service, when I try to explain this she Screams at me saying I am not going to argue with you you have a 200A Panel 200x120%=240-200=40 so you can only use a 40A backfeed on the PV System. Perhaps I need to got to her supervisor, I am really trying to avoid this.

as for my new calc's they look ok to you?

 

[Smart $]

I Understand that too, but the lady at B&S is stuck on her Opinion that there is only a 200A Service, when I try to explain this she Screams at me saying I am not going to argue with you you have a 200A Panel 200x120%=240-200=40 so you can only use a 40A backfeed on the PV System. Perhaps I need to got to her supervisor, I am really trying to avoid this.

as for my new calc's they look ok to you?

17 Enphase M215 microinverters is the max per 240V 20A circuit (re: Enphase M215 spec sheet).

What size/ampacity are service conductors supplying the meter/main/panel combo? You feasibly could have a 200A service supplying 320A service equipment. However, that would not affect the calculation. For load-side connections, it is based entirely on the sum of supply OCPD's vs. bus rating @ 120%.

 

[jaggedben]

There are two busbars in the main panel. There's the one that the two mains are connected to, and then there's the one for the load center section. Are they both the same rating? I think you need the info from the label on the panel, the catalog is a little too vague.

 

[sreagle]

There are two busbars in the main panel. There's the one that the two mains are connected to, and then there's the one for the load center section. Are they both the same rating? I think you need the info from the label on the panel, the catalog is a little too vague.

Only One Set of Busses to Both 200A MB's
On the load side "BUSS" of the meter Both 200A. Breakers are Bolted to the same Buss
One of the 200A Breakers On the Load Side has Lug Only Connection Point from there goes to the House Panel Underground
The Other 200A Breaker On the Load Side has a Buss for Circuit Breaker, the Only breaker on the Buss "Currently" is a 15A 120v feeding a outdoor light fixture
Panel Info;
400A Panel
320A Buss
Two 200A MB neither is feed by the other, both on same Line Side Buss
One 200A MB Load Side LUG Only
Other 200A MB Load Side has Breaker Buss
Overhead Feeder with the approate kit from the manufacture
I would have to check on the feeder size to be exact not that that matters was permited as a 400A Panel I think 500 but would have to double check that

for what ever reason the Person at the local B&S Refusses to accept this as a 400A. Panel Info... as a mater of fact the mear mention of it and she goes Balistic on me and refusses to talk to me anymore, I never raised my voice, I was Never rude to her etc,
BTW this panel is Existing and Permited with them.

 

[sreagle]

17 Enphase M215 microinverters is the max per 240V 20A circuit (re: Enphase M215 spec sheet).

What size/ampacity are service conductors supplying the meter/main/panel combo? You feasibly could have a 200A service supplying 320A service equipment. However, that would not affect the calculation. For load-side connections, it is based entirely on the sum of supply OCPD's vs. bus rating @ 120%.

500kcm I belive I would have to double check that to be 100%
It's Permited as a 400A. Panel, and I will be double checking that too.

 

[jaggedben]

Only One Set of Busses to Both 200A MB's
On the load side "BUSS" of the meter Both 200A. Breakers are Bolted to the same Buss

That's one set of busbars. Let's call in the line side busbar. (Line side of the service disconnecting means.)

...The Other 200A Breaker On the Load Side has a Buss for Circuit Breaker,

That's another set of busbars. Let's call it the load side busbar. (Load side of the one of the service disconnecting breakers.)

What is the rating of each?

Panel Info;
400A Panel
320A Buss

Unfortunately that's still kind of vague, and doesn't make much sense. (A panelboard rating can be less than the busbar, but not greater.)

If it means that the line side busbar is 400A and the load side busbar is 320A, then you're golden (and your AHJ needs to get with the program). I'm just not sure if the catalog info makes it crystal clear that that's what the ratings are. Obviously your going to need some pretty robust documentation to win the argument with the AHJ, and I don't think you've presented it here yet.