Interpretation for CEC 690.64(B)(7) - Unless the panelboard is rated not less than...

[Nephi]

I really did graduate from college with a 4 year degree, in engineering no less, but this logic is getting the better of me. Maybe it's the cold I'm fighting....

Here is the requirement from the City (and CEC):

Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location. The bus or conductor rating shall be sized for the loads connected in accordance with CEC Article 220. A permanent warning label shall be applied to the distribution equipment with the following: [CEC 690.64(B)(7)]

WARNING
INVERTER OUTPUT CONNECTION
DO NOT RELOCATE THIS
OVERCURRENT DEVICE

Does this mean if the Panel is rated to more than the sum of the OC devices then something or other? or does it mean if the Panel is rated lower than the sum of the OC devices? Very confusing.

And when it says "a connection" what does that refer to? Any old connection to the panel board, or some specific connection?

Can anyone translate into plain English?

In short, should I put this label on my single SMA SB4000-TL-US String inverter?

[captaindomon]

My installer put that sticker next to the breaker supplying power from the solar inverter to the main panel. So it's a sticker in my main panel (I think it's also on the small "AC Disconnect" sub-panel as well). Not saying that is correct, but that's where mine is.

[Sunking]

I really did graduate from college with a 4 year degree, in engineering no less, but this logic is getting the better of me. Maybe it's the cold I'm fighting....

They do not teach electrical code in college. To learn code takes several years of reading and doing it under supervision. It takes an Electrician a minimum of 7 years to take the test.

Here is the requirement from the City (and CEC):

Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location. The bus or conductor rating shall be sized for the loads connected in accordance with CEC Article 220. A permanent warning label shall be applied to the distribution equipment with the following: [CEC 690.64(B)(7)]

WARNING
INVERTER OUTPUT CONNECTION
DO NOT RELOCATE THIS
OVERCURRENT DEVICE

Does this mean if the Panel is rated to more than the sum of the OC devices then something or other? or does it mean if the Panel is rated lower than the sum of the OC devices? Very confusing.

And when it says "a connection" what does that refer to? Any old connection to the panel board, or some specific connection?

Can anyone translate into plain English?

In short, should I put this label on my single SMA SB4000-TL-US String inverter?

What they are saying is just what it says. If the sum of the breakers are greater than the panel rating (which almost always does), you use the bottom Two Breaker Positions (41 and 42 in a 200 amp panel) to connect the GT Inverter. The reason is extremely simple even a college grad can figure out. The current from the GTI is Negative Sum or Subtractive across the Buss. It does not add current, it reduces current. If you connect to positions 1 & 2 is be ADD current which you DO NOT WANT.

Example a 200 amp Main Breaker panel has 42 positions. The most common breaker you have is 20 amps. 42 x 20 amps = 840 amps. Not saying you will have all 42 positions filled, all it takes is just 10 positions used to exceed 200 amps.

Here is all you need to know. Makes no effing difference what the breakers add up to. You are not paid to know that nor should you care. All you need to know is to connect the Inverter to the last 2 positions in the Main Breaker Panel, and put the stickers on the Main Breaker Panel Breaker Assignment list inside the door. Will pass code every time and you get a check regardless of what the breakers add up to. No one gives a crap if you use the last two positions. .

It is like Bonding the Service to Ground. You don't give a crap about resistance or anything. You drive two rods, use 4 AWG to bond it, collect a check, and go home. Will pass code inspection every time. Try to drive 1 rod now you have to convince the Inspector it wil never rise to more than 25 Ohm's. Impossible to do that. Drive two rods and call it good. No one gives a crap what the resistance really is as it is meaningless.

[emartin00]

If your main feed breaker, and your solar feed breaker equal more than the rating of the panel board, they have to be at opposite ends. So if you have a 200A panel, with a 200A main breaker, the solar feed has to be at the opposite end. If you have a 200A panel, and only a 150A main breaker, you could put up to a 50A solar feed anywhere you want.

A connection is simply any feed/load on the panel. Most likely, a circuit breaker connection.

[foo1bar]

I believe this is the part you're trying to understand:
"Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall ... "

If the panelboard is rated more than the sum of the breakers, you can ignore the rest.
Otherwise you *SHALL* do <rest of statement>.

ex. 200A panel with 20A, 30A, 30A, and 100A breakers - the sum of the breakers (including the 100A feeding into it) is 180A.
180A is less than the 200A rating, therefore you can put the breakers in whichever order you want (you don't need to follow the "shall ..." part.)
Or put in the phrasing they used
200A panel is rated not less than 20+30+30+100 (sum of ALL breakers)

Note that the 100A breaker I am using in this example is feeding the panel - it is often a different size/format breaker than the regular branch circuit breakers.



I'd just do like Sunking suggested though - use an end-feed panel, use the last two spots farthest from the feed in for the breaker for the inverter and put a label next to those breakers with the required verbiage.

[sensij]

Guys, the code says "Overcurrent devices supplying it'. Load breakers don't matter, and aren't a part of the calculation in this reference. Only supply breakers.

[PVAndy]

Guys, the code says "Overcurrent devices supplying it'. Load breakers don't matter, and aren't a part of the calculation in this reference. Only supply breakers.

I agree with that. Please ignore the rest of this thread. There are just too many serious errors in the "facts" that are presented. I design systems every day from 5KW to multi megawatt and I can barely cull out all the incorrect statements.

[Nephi]

So I have a 200A panel with a 200A feed so the solar CB should be in position B, furthest from the supply. Is that right?

[Sunking]

So I have a 200A panel with a 200A feed so the solar CB should be in position B, furthest from the supply. Is that right?

Correct. As stated earlier if it is in the last position, it will pass code no matter what. Think of it like driving 70 in a 75 mph zone. It is a STUPID CODE. Just state is SHALL BE in the last position and be done with it.

[Sunking]

I agree with that. Please ignore the rest of this thread. There are just too many serious errors in the "facts" that are presented. I design systems every day from 5KW to multi megawatt and I can barely cull out all the incorrect statements.

Care to come over to Mike Holt's Code Forum and talk about it?

This Forum is the last place someone should go for Code Answers.

[sensij]

Correct. As stated earlier if it is in the last position, it will pass code no matter what. Think of it like driving 70 in a 75 mph zone. It is a STUPID CODE. Just state is SHALL BE in the last position and be done with it.

No, it will pass code only if the PV breaker is 40 A or less. 120% of 200 A = 240 A. Subtract the existing 200 A supply breaker leaves 40 A remaining available for PV.

If the 200 A main supply breaker was replaced with a smaller one... say, 175 A, there are more possibilities.

1) A 20 A PV breaker could be put anywhere in the panel. 175 A + 20 A = 195 A, less than the panel rating and therefore compliant.

2) 240 A - 175 A = 65 A, so up to a 60 A PV breaker could be used if installed at the opposite end of the panel from the supply.

[Sunking]

No, it will pass code only if the PV breaker is 40 A or less. 120% of 200 A = 240 A. Subtract the existing 200 A supply breaker leaves 40 A remaining available for PV.

If the 200 A main supply breaker was replaced with a smaller one... say, 175 A, there are more possibilities.

1) A 20 A PV breaker could be put anywhere in the panel. 175 A + 20 A = 195 A, less than the panel rating and therefore compliant.

2) 240 A - 175 A = 65 A, so up to a 60 A PV breaker could be used if installed at the opposite end of the panel from the supply.

You don't get it. Put the Inverter in the last position and it will pass code every time. Put it elsewhere and you raise questions. Just like Ground Rods, drive two and collect a check. Will pass every time no questions asked.

Another great example. Can you use #14 AWG on a 20 amp breaker?

Yes, if certain conditions are met. Use a 14 AWG and you can bet the Inspector is going to have questions and want you to prove it. Use a #12 AWG or larger and the Inspector could care less what it is used for.

[cebury]

I think everyone can appreciate the simplicity you are describing Sunking. But after reading Sensij's post, now I understand why it includes the conditional at the start of the code.

[bcroe]

Rules are what they are. But in truth if the feeding breakers are derated to total no more than the busbar capacity, it
cannot be overloaded no matter where they are placed. On the other hand you could put a 200A feed at each end of
a 200A busbar, and there would still be no possible way to overload it with load breakers of up to 200A (since the
currents are never additive in the bus. Maybe the rule makers knew that, but they like belt & suspenders? Bruce Roe