Interpreting Code for AC Disconnect Location

[kboo]

Hi all,

Just looking for someone who knows what they are talking about to help me out here. I am in the process of my solar install and I have 2 parties arguing over what is up to code and what is not and I was looking for some clarity. I have panels on my roof and a string inverter in my garage. Obviously the DC disconnect is at the bottom of the inverter and the AC disconnect is next to the inverter in the garage. This is where I would prefer the disconnect to be rather than on the side of my house. The solar company is saying that they install both the DC and AC disconnects inside the garage all the time and that it is up to code.

The city is saying that both DC and AC need to be outside to be up to code. I have a hard time believing this, as I have seen friends who have theirs in the garage and they all passed inspection recently with no problems. I especially have a hard time believing that the DC disconnect needs to be outside since it is literally built into the inverter, which I know doesn't need to be outside.

Now cast away your beliefs in "how it should be" and tell me what the code actually says. As I read it it says the disconnect must be "either on the outside of a building...or inside nearest the point of entrance of the system conductors." Now I don't know what that second part means exactly and when I asked the the city inspector to explain it, he was rude enough to tell me to "consult the beginning of the code where it says this is not for untrained people" and essentially to stop trying.

In section 690.15(D) it says the DC and AC disconnects must be in sight of the inverter. So now basically it is saying that they should be in the garage. Does this mean we should have one in the AC disconnect in the garage (in sight of the inverter) and one outside? Or is inside the garage count as "inside nearest the point of entrance of the system conductors"?

HALP!

 

[ggunn]

Hi all,

Just looking for someone who knows what they are talking about to help me out here. I am in the process of my solar install and I have 2 parties arguing over what is up to code and what is not and I was looking for some clarity. I have panels on my roof and a string inverter in my garage. Obviously the DC disconnect is at the bottom of the inverter and the AC disconnect is next to the inverter in the garage. This is where I would prefer the disconnect to be rather than on the side of my house. The solar company is saying that they install both the DC and AC disconnects inside the garage all the time and that it is up to code.

The city is saying that both DC and AC need to be outside to be up to code. I have a hard time believing this, as I have seen friends who have theirs in the garage and they all passed inspection recently with no problems. I especially have a hard time believing that the DC disconnect needs to be outside since it is literally built into the inverter, which I know doesn't need to be outside.

Now cast away your beliefs in "how it should be" and tell me what the code actually says. As I read it it says the disconnect must be "either on the outside of a building...or inside nearest the point of entrance of the system conductors." Now I don't know what that second part means exactly and when I asked the the city inspector to explain it, he was rude enough to tell me to "consult the beginning of the code where it says this is not for untrained people" and essentially to stop trying.

In section 690.15(D) it says the DC and AC disconnects must be in sight of the inverter. So now basically it is saying that they should be in the garage. Does this mean we should have one in the AC disconnect in the garage (in sight of the inverter) and one outside? Or is inside the garage count as "inside nearest the point of entrance of the system conductors"?

HALP!

Here in Austin if the DC goes into a building then it must have a disconnecting means before it does so. I couldn't find it in the NEC, so it might be a local add on to it.

 

[Carultch]

Hi all,

Just looking for someone who knows what they are talking about to help me out here. I am in the process of my solar install and I have 2 parties arguing over what is up to code and what is not and I was looking for some clarity. I have panels on my roof and a string inverter in my garage. Obviously the DC disconnect is at the bottom of the inverter and the AC disconnect is next to the inverter in the garage. This is where I would prefer the disconnect to be rather than on the side of my house. The solar company is saying that they install both the DC and AC disconnects inside the garage all the time and that it is up to code.

The city is saying that both DC and AC need to be outside to be up to code. I have a hard time believing this, as I have seen friends who have theirs in the garage and they all passed inspection recently with no problems. I especially have a hard time believing that the DC disconnect needs to be outside since it is literally built into the inverter, which I know doesn't need to be outside.

Now cast away your beliefs in "how it should be" and tell me what the code actually says. As I read it it says the disconnect must be "either on the outside of a building...or inside nearest the point of entrance of the system conductors." Now I don't know what that second part means exactly and when I asked the the city inspector to explain it, he was rude enough to tell me to "consult the beginning of the code where it says this is not for untrained people" and essentially to stop trying.

In section 690.15(D) it says the DC and AC disconnects must be in sight of the inverter. So now basically it is saying that they should be in the garage. Does this mean we should have one in the AC disconnect in the garage (in sight of the inverter) and one outside? Or is inside the garage count as "inside nearest the point of entrance of the system conductors"?

HALP!

Check whether NEC 2014 applies. This has a new contentious section in it, related to disconnecting means. 690.12.
http://www.electricalcodecoalition.org/state-adoptions.aspx

 

[Carultch]

Here in Austin if the DC goes into a building then it must have a disconnecting means before it does so. I couldn't find it in the NEC, so it might be a local add on to it.

What if you use a module-level technology, such as power optimizers? These shut down to safe DC levels, when you shut off the inverter, and eliminate the need to have any location specific disconnect on the DC side. Unless there are replaceable components, like fuses in a DC combiner, on the roof.

 

[Zee]

Unless 2014 Rapid Shutdown requirements apply:

DC
If dc conduit is metal inside building, then dc disco adjacent or integrated with inverter is per code.
AC
AC disco within line of sight of inverter. In garage near inverter would do it.

Any other AC disco required outside could be a UTILITY requirement to have a lockable and visibly off AC disco adjacent to meter/main panel. They have that right and it is in addition to the Code.
Otherwise the "AC disconnect" for the utility is the PV breaker in the meter/main.

 

[jaggedben]

...tell me what the code actually says. As I read it it says the disconnect must be "either on the outside of a building...or inside nearest the point of entrance of the system conductors."

Note the very important exception to that rule, which says that if the installation complies with 690.31(E), then the disco can be remote from the point of entry, e.g. at the inverter. 690.31(E) basically proscribes certain wiring methods that protect the conductors better than others, primarily metal raceways. Most installers do this now out of habit. (EMT is cheap and meets the requirements).

I've never argued much over 'nearest the point of entrance' but it basically means that you put the disconnect at the nearest possible point where you can practicably mount it. If you put any more significant length of wiring in between you are not following this.

There is no NEC code provision whatsoever that requires the AC disconnect to be outside, but as Zee said, many utilities require one that can be accessed by their employees without breaking into the property.

Now I don't know what that second part means exactly and when I asked the the city inspector to explain it, he was rude enough to tell me to "consult the beginning of the code where it says this is not for untrained people" and essentially to stop trying.

Well he's just an -----. Because that's not what it says.

In section 690.15(D) it says the DC and AC disconnects must be in sight of the inverter.

Actually it says 'grouped', which is more stringent than just 'within sight' but is otherwise open to interpretation. One AHJ I work with interprets this as meaning 'as close as possible' and another as 'within 6ft.' The first does not allow a breaker in a panel to meet the requirement, and the second one does. Don't waste time searching for a more definitive definition in the code because it ain't there.

(BTW I gather your going off the 2011 code because of this reference. These sections were completely reorganized and renumbered in the 2014 code. Other sections I quote in this post are also 2011.)

At any rate...

So now basically it is saying that they should be in the garage.

Yup.

Does this mean we should have one in the AC disconnect in the garage (in sight of the inverter) and one outside? Or is inside the garage count as "inside nearest the point of entrance of the system conductors"?

Again, you need an AC disconnect near the inverter, and you only need one outside if the utility demands it. You need a DC disconnect near the inverter, and you only need one outside if the wiring method inside doesn't meet 690.31(E).

Unfortunately, you are really at the mercy of the inspector unless you have some kind of 'over' on him, such as a strong friendship with a local politician who can order him to follow the code precisely. For customers or small contractors, it generally comes down to taking monumentally less time and money to put in more disconnects than to fight.

 

[SolarPro]

Here in Austin if the DC goes into a building then it must have a disconnecting means before it does so. I couldn't find it in the NEC, so it might be a local add on to it.

See 690.31(G). I'm not on board with AE's interpretation of what complies with this requirement. [The Code clearly says you can run within metal conduit to the first readily accessible disconnect.] But AE has been very consistent with their (mis)interpretation, which is a plus. Arguably, the worst is when you get different interpretations within the same AHJ.