[RE-wrenches] "its a UL listed assembly"

[Matt Lafferty]

Hi Nick,
 
Waddya mean "another supply side tap nightmare"? This isn't the first?
 
RE: "Void the listing..." 
 
Let's be honest. I don't know about you or anyone else on this list, but I'm
pretty sure that every single supply side connection I've seen in
wall-mounted meter/main combination service panels has voided the listing on
the thing. These were factory assembled and listed as such. Just because,
"it's been done before", does not change the fact that it's not what the
panel manufacturer had in mind when the thing originally left the factory.
This applies to equipment with conductors as well as busbars. If they had
intended connections such as this, they would have provided the means to do
it and listed (no pun intended) the approved devices on the label inside the
cover. The label that is no longer legible....
 
If an inspector plays the "all equipment must be listed for the use" card,
you have a couple options. Smaller PV system on a load side connection comes
to mind. Larger service panel comes to mind. Different service configuration
(i.e. separate meter socket), comes to mind. Paying for a NRTL to list the
final product comes to mind, along with a few cuss words. Pissing up a rope
trying to get the guy to back down from his 100% defensible position is not
jumping out there as a viable option to me.
 
I'm not exactly sure what you hoped to gain by swapping from TW to THHN from
a code perspective.... I fully understand your service entrance feeder table
concept, but what do you gain, really? Other than the fact that you will be
violating the listing by tapping in that section anyway, you can
theoretically put up to 110A of PV on that conductor and stay with the #1AWG
TW (Table 310.16) under all the tap rules, etc. The utility is upstream of
your connection and the downstream (house) is protected by the 100A main
breaker. Unless it's an FPE, or Bulldog, or Zinsco... In those cases, Buddha
alone knows how many amps shall pass and sparks shall fly before the breaker
trips... Are you putting in more than 100A of PV on a utility service that
is sized for 100A? If that's the deal, then a bigger service is necessary.
(Side Note: IMHO, PV output capacity greater than the customer's service
needs shouldn't qualify for Net Metering in any way shape or form.) 
 
Just because the whole listing thing around supply side connections is what
it is, doesn't mean that one could not SAFELY accomplish a supply side tap
in some of these boxes. (Note: Double negative = positive, in case you
missed it.) Some, but certainly not all. The problem is, "Safety" is
subjective. What one person calls safe, I might not, and vice versa. This is
where standards come into place. Standards, such as UL XXXX, are developed
to define the conditions that constitute safety in various products
depending on their use. NRTLs judge whether a product meets these conditions
or not. If the product meets the conditions, the NRTL lists the product to
such and such a standard. The NEC defers to listing as the be-all-end-all.
As do building officials in many cases. Some use this as a club to hide
their own incompetence, no question. That being said, we
 
I wouldn't normally bring all this up in this venue, but from what I am
seeing, the cat is out of the bag already... The horse has left the barn...
I suspect that, in most cases, supply side connections will largely be a
theoretical concept only in the very near future. We must push equipment
manufacturers to develop products which facilitate safe, code-compliant
interconnection at existing services. 
 
I would contact a company like Marwell  http://www.marwellcorp.com/  and
describe your supply side connection woes.... For small to modest size
systems, I think going right in behind the meter is best done outside the
box.... Look for an E/Z 1000-0 meter extender in the configuration you like
from this page  http://www.marwellcorp.com/online-catalog/5-1000. You can
order it with KO up to 1". It's not standard a standard option for this
extender, but tell them you want NC-400-L clips on the load jaws. You will
need to get them to buy off on it, but most utilities will accept it, though
they may want to put a lock on it. The trick is getting your neutral
conductor routed through it. 
 
It's a place to start...
 
Matt Lafferty

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nick Vida
Sent: Friday, November 20, 2009 4:37 PM
To: wrenches
Subject: [RE-wrenches] "its a UL listed assembly"


wow wrenches,

fun solar day for me. Another supply side tap nightmare.

Have any of you ran into a situation where the AHJ will not let you upgrade
the feeders from the meter to the
 main breaker because it "voids the UL listing"? In this case I had 1 AWG
feeding a 100 amp main, but it was
 type TW which is not on the feeder exception 310.16. In running into the
typical daftness on 690.64 I asked
 if I could replace the 1 AWG TW with Type THHN so the feeder chart would
apply and there would be 150
 ampacity wires feeding the 100 amp main. No luck, all frustration.

Any wrenches have any thoughts on this?

Nick Vida


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20091120/16a3d186/attachment-0004.html>