Should the neutral be switched in the AC disconnect?

[photonboy]

Just read a 2016 thread here on this question but it wasn't resolved. 2023 690.12 says "The PV system disconnecting means shall simultaneously disconnect the PV system conductors that are not solidly grounded from all conductors of other wiring systems" I'm not sure what is meant by that last part in bold. The neutral is the "grounded conductor" but is it "grounded from all conductors of other wiring systems? What are the other wiring systems being referred to?

I have never switched the neutral in any of my installs and rarely see it now but am starting to see it a bit more often. My gut instinct, based on what I'm not sure, is that it should not be broken, but can't find any clear reasoning one way or the other.

Any ideas?

Thanks.

 

[jaggedben]

If it's an AC neutral then it's solidly grounded. I'm assuming it's an AC disconnect because a typical PV circuit wouldn't have 3 conductors.* So the neutral is not required to be switched in you application, I'm just about positive. It is allowed to be switched simultaneously, but not required, see 404.2(B) exception.

690.12 does not have that language, I think you are referring to 690.13. 690.13 covers all types of PV systems including ones where the PV disconnect is a DC disconnect and the positive or negative PV conductor may be 'functionally grounded' instead of solidly grounded, although this is rarer these days. So that's why it's written that way, it's covering a precise situation that doesn't apply to AC neutrals.

*(I'm sure you don't have the quite rare bi-polar array).

 

[Dennis Alwon]

You can switch the neutral as long as the ungrounded conductors are also switched. What you cannot do, in almost all situations, is have the neutral connected to an overcurrent device.

 

[Dennis Alwon]

I haven't seen an a/c unit with a neutral in 20 years or more. The amana units were the only ones I know of that used a neutral

 

[jaggedben]

The requirement is:
"shall disconnect
(PV system conductors that are not solidly grounded)
from
(all conductors of other wiring systems)."

Other wiring systems typically just means the normal building distribution.

 

[jaggedben]

I haven't seen an a/c unit with a neutral in 20 years or more. The amana units were the only ones I know of that used a neutral

AC is alternating current not air conditioning.
AC disco is PV jargon to distinguish from DC disco when necessary.

 

[Dennis Alwon]

AC is alternating current not air conditioning.
AC disco is PV jargon to distinguish from DC disco when necessary.

haha-- I was wondering why PV was mentioned.... slow brain here

 

[pv_n00b]

I haven't seen an a/c unit with a neutral in 20 years or more. The amana units were the only ones I know of that used a neutral

Yeah, until the NEC required a receptacle at the AC unit no one was running neutrals. This was a big problem when I was working with a larger HVAC manufacturer years ago that wanted to offer PV with HVAC. They wanted to back feed the branch circuit with microinverters but there was no neutral on older HVAC installs. Hilarity ensued.