David,
The NEC doesn't require UL listing. The most appropriate section of
the code about this is Article 110, Requirements for Electrical
Installations, it requires equipment to be approved. In many
jurisdictions, such as Oregon, that means evaluated and approved by a
testing lab such as UL.
Kent Osterberg
Blue Mountain Solar, Inc.
David Brearley wrote:
Thanks, Bill.
Glad to hear you think the HU series is still a good option.
When I was making the rounds at SPI, I stopped by the Eaton booth and
got the sense that they were gunning for Square D. They made light of
Square D’s self-certification of the HU series discos. The rep also
made a statement about the new Eaton dc discos being the only ones
designed to meet UL1741 requirements. When I got home, the first thing
I looked up was 690.4(D). This doesn’t say anything about dc
disconnects needing to be listed to some special PV standard.
Is there a movement in this direction? Is there a UL1741 standard for
dc discos that is somehow different that the standard used for other dc
disconnects?
Best,
David
On 1/11/10 5:28 PM, "Bill Brooks" <billbroo...@yahoo.com> wrote:
David and Kirpal,
It is ultimately up to the AHJ whether or not they accept the
Schneider/Square D self certification. That is a judgment call the
installer needs to clear with the AHJ. That being said, having Square D
behind the rating of a switch is a whole lot more than any one of the
smaller companies making equipment for the PV industry.
I will continue to use the 30, 60, and 100-amp versions in the way
recommended by the manufacturer because it is a huge saving in cost and
they are well made switches. I will also check with the local AHJ
before installing them in case they are not going to pass it. You have
to remember you are working with one of the largest electrical
suppliers in the world. They have a huge reputation with local
jurisdictions.
Eaton has been in the process of trying to make a big deal out of this
issue since they want a piece of the market. Fortunately, they are
starting to build products specifically for the PV industry, which I
applaud. However, they need to be given a hard time for the way they
have tried to imply that all Square D switches are not properly listed.
They won’t admit to that because they would end up in a legal battle,
but that is essentially what they have been doing. Square D still has
the largest selection of dc-rated equipment on the market. Eaton has a
long way to go.
In a recent project that I reviewed, the engineer pulled the Square D
400-amp disconnect and replaced it with an Eaton disconnect at the
insistence of the Eaton rep. The Eaton product was not properly rated
or listed for the voltage while the Square D product was. This is the
insanity that needs to stop.
Bill.
From:
re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org]
On Behalf Of David Brearley
Sent: Monday, January 11, 2010 11:39 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Square D DC disconnects
Kirpal,
Have you checked out the SolarBOS disconnecting combiners? Their 28A
version might be ideal for large resi or small commercial applications.
For larger projects, Blue Oak PV Products and AMtec Solar also have
disconnecting combiners.
Thanks for sharing the updated Square D tech note. I had no idea that
the Square D HU Series disconnects were not UL-listed when used as
described in the older tech notes. The fact that this is not a
UL-listed use of the heavy duty safety switch, pretty much means that
it is not an option for integrators. As far as I know, there is no
other product that is listed for this use.
David Brearley, Senior Technical Editor
SolarPro magazine
NABCEP Certified PV Installer ™
david.brear...@solarprofessional.com
On 1/9/10 4:14 PM, "Kirpal Khalsa" <solarwo...@gmail.com> wrote:
Hi All......
I recently came across a revised technical bulletin from square D ( http://ecatalog.squared.com/pubs/Electrical%20Distribution/Safety%20Switches/Heavy%20Duty/3110DB0401.pdf
)......we have for years been using the Square D DC Disconnect of
various amperages (30, 60, 100) as disconnects leading upto the
inverter from the array.....we have frequently wired one string to each
of the three poles of the disconnect......we have had this
configuration inspected by inspectors regularly with approval
everytime......this new revision of the document from Square D shows
this is no longer a UL listed method.....they are now stating in this
document that they are "self certifying" this technique.......have any
of you come across this or know why Square D has back tracked?
Something else I noticed is that they have raised the amperage rating
on the 30A disconncect per pole by 2 amps from 18 to 20 which is good
especially when using higher amperage modules like Evergreen ES-A
series which would not have ben allowed to use the 30A disconnect as
the short circuit current rating was too high for the derated poles.
This is not a huge concern as more and more of the inverters we are
using these days have an appropriate disconnect included with the
inverter negating the need for an additional stand alone disconnect.
On a side note............Are there any other manufacturers making listed
muiti pole DC disconnects in which each pole can handle one string?
Also there is definately a need for roof mounted multi string (1-4
strings) combiner boxes with integrated DC disconnects for residential
applications that have a reasonable price.......any one know if any?
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