Supply Side Tap

[iwire]

The key passage of all that is that it is up to the AHJ to determine if the modifications require a UL re-evaluation.

You can do whatever you want to listed equipment as long as it is acceptable to the AHJ. UL has no authority at all.

 

[pv_n00b]

The key passage of all that is that it is up to the AHJ to determine if the modifications require a UL re-evaluation.

You can do whatever you want to listed equipment as long as it is acceptable to the AHJ. UL has no authority at all.

No, you are missing the whole point on the listing. It's not up the the AHJ to determine if the Listing still applies, only UL controls listing equipment. Any field modification that is not allowed by the listing renders the equipment no longer listed because UL can not longer determine it the equipment meets the listing requirements, that's the key passage.

It's up the the AHJ to determine if they want to accept the modified equipment knowing that it may no longer meet the listing standards, or do they want to order a field examination to have the equipment re-listed.

 

[iwire]

No, you are missing the whole point on the listing. It's not up the the AHJ to determine if the Listing still applies, only UL controls listing equipment. Any field modification that is not allowed by the listing renders the equipment no longer listed because UL can not longer determine it the equipment meets the listing requirements, that's the key passage.

It's up the the AHJ to determine if they want to accept the modified equipment knowing that it may no longer meet the listing standards, or do they want to order a field examination to have the equipment re-listed.

Those two paragraphs of yours are in direct conflict.

UL has zero power, zero authority. They may own the standard an item is listed too but it is up to the AHJ to say yes or no.

You have mentioned this a couple of times

Any field modification that is not allowed by the listing renders the equipment no longer listed

And I submit that is false, we do things every day to equipment that is not specifically addressed in the listing or labeling.

 

[jaggedben]

How I would put it: An AHJ can refuse to pass this type of modification of service equipment without a field re-listing, and they can point to fairly clear NEC passages to justify that.

It's sort of silly, in my opinion, to bring up that an AHJ can decide not to enforce a requirement, when the OP asked "Is that okay ... is there a caveat in the NEC?" I mean, yes, technically an AHJ could probably cover their butt with 90.4 in some of these add-to-existing-bolt situations. But 90.4 could be the ultimate answer to any discussion about code requirements on this forum, so that is basically begging the question.

 

[mwm1752]

How I would put it: An AHJ can refuse to pass this type of modification of service equipment without a field re-listing, and they can point to fairly clear NEC passages to justify that.

It's sort of silly, in my opinion, to bring up that an AHJ can decide not to enforce a requirement, when the OP asked "Is that okay ... is there a caveat in the NEC?" I mean, yes, technically an AHJ could probably cover their butt with 90.4 in some of these add-to-existing-bolt situations. But 90.4 could be the ultimate answer to any discussion about code requirements on this forum, so that is basically begging the question.

I disagree with the silly part
To accept a field modification is not a simple decision the AHJ is weighing the options for life safety & accepting the responsibility of solid research for his rendering -- to be unprepared for consequences simply shows negligence

 

[iwire]

How I would put it: An AHJ can refuse to pass this type of modification of service equipment without a field re-listing, and they can point to fairly clear NEC passages to justify that.

I agree they can, they can also approve it just like they do for countless field modifications we all do.

It's sort of silly, in my opinion, to bring up that an AHJ can decide not to enforce a requirement, when the OP asked "Is that okay ... is there a caveat in the NEC?" I mean, yes, technically an AHJ could probably cover their butt with 90.4 in some of these add-to-existing-bolt situations. But 90.4 could be the ultimate answer to any discussion about code requirements on this forum, so that is basically begging the question.

As seems to be the case people with different views then yours are silly or just don't understand things as well as you.

 

[pv_n00b]

Home Power reminded me that there is another approach: http://www.homepower.com/articles/s...ode-corner-difficult-utility-interconnections

This approach bypasses the existing meter in the meter main panel and installs a new meter box. Then the supply side interconnection can be made in a junction box between the old panel and the new meter.

 

[tritium]

But, what about...

But, what about...

I have an installation coming up that will be roof-mounted to an "adjacent" structure (read: 120ft from the house, approx. 220 ft conductor run from inverters to the meter where the required utility disconnect will be) which has a separate service from the house, but the inverter outputs will only be tied to the main residence's service. The system is large enough that we can't interconnect on the load side, so here I've stumbled trying to figure out the new language of 2014's 705.31 and rules for connecting to the supply side of the service disconnect.

The conductors for the run were sized for the voltage drop (running 4/0 aluminum) and per 705.65(A) Exception (2), an OCPD "shall not be required" for the inverter output conductors if the "short circuit currents from all sources do not exceed the ampacity of the conductors".

Well, 4/0 aluminum's ampacity is 205, and the panel combining the two inverters' output has OCPD for each of those smaller branches. If the conductors and equipment are out of harm's way here, and the disconnect allows for the opening of the circuit regardless of fusing, then isn't the code intention of 705.31 satisfied?

Still putting in a fused disconnect at the end of the day for peace of mind here, but I see these as contradictory given certain circumstances.

 

[jaggedben]

I have an installation coming up that will be roof-mounted to an "adjacent" structure (read: 120ft from the house, approx. 220 ft conductor run from inverters to the meter where the required utility disconnect will be) which has a separate service from the house, but the inverter outputs will only be tied to the main residence's service. The system is large enough that we can't interconnect on the load side, so here I've stumbled trying to figure out the new language of 2014's 705.31 and rules for connecting to the supply side of the service disconnect.

The conductors for the run were sized for the voltage drop (running 4/0 aluminum) and per 705.65(A) Exception (2), an OCPD "shall not be required" for the inverter output conductors if the "short circuit currents from all sources do not exceed the ampacity of the conductors".

Well, 4/0 aluminum's ampacity is 205, and the panel combining the two inverters' output has OCPD for each of those smaller branches. If the conductors and equipment are out of harm's way here, and the disconnect allows for the opening of the circuit regardless of fusing, then isn't the code intention of 705.31 satisfied?

Still putting in a fused disconnect at the end of the day for peace of mind here, but I see these as contradictory given certain circumstances.

"All sources" includes the utility. So no, you can not get away with not having an OCPD to protect the conductors from utility fault current.

As far as the separate structure, if the conductors going to it are installed for more than 10ft on the house in any way, then I'd say you need a disconnect within 10ft of the service. If not, maybe that's a bit of a gray area. But regardless, you'd need a disconnect at the separate structure per Article 225.