UL listing of lightning arrestors [RE-wrenches]

[Bill Brooks]

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Allan and all,

The only thing that I would add to this generally factual discussion on
UL-recognized is that it primarily refers to a component that has had some
testing done on it (what testing differs on every component and is specified
by the manufacturer). For instance, there is at least one battery that is
UL-recognized. What does this mean? It actually means very little. It turns
out that the battery I am referring to is using a plastic case that has been
tested. Nothing related to the other physics or the electrical
characteristics of the battery have been tested other than the plastic in
the case. Some have mistakenly assumed that this battey is superior to other
batteries because of this UL-recognition. However, the only real advantage
this battery presents is that if a manufacturer like Outback Power, or
Beacon wanted to use this battery in a fully listed battery system assembly,
they would not have to test the case material, whereas they would have to
have to test the case material tested for a non-UL-recognized battery.

As it relates to silicon-oxide varistors (SOVs), the benefit of having the
UL-recognition on the Delta lightning arrestor is that an inverter or charge
controller manufacturer could incorporate this device into their "listed"
product, and not have to repeat the tests already paid for by Delta. So the
valid question is why hasn't any PV inverter or charge controller
manufacturer embraced this product? We have been using the product for years
and it has done a reasonably good job protecting PV systems. It is also used
extensively in standard ac systems throughout areas of the U.S. with high
lightning occurances. It is inexpensive, and if applied properly has a very
real benefit for PV systems. I honestly do not understand why inverter and
charge controller manufacturers do not embrace these products to assist
their on-board devices by providing supplemental surge protection. I say use
them whenever the local jurisdiction does not prohibit their use. 

Choosing the correct SOV is the issue. That is why it would be great for
some of these manufacturers, that have the engineering know-how, to
incorporate the specific products into their units so that the installer
does not have to wonder which one to pick.

Bill.



Kirk,
As I understand it, the backwards-UR means recognized when used as part of a
listed assembly. This means that the product can't be used as a stand-alone
component, installed by us in general application. It may be installed by a
manufacturer as part of a listed product, meaning, for example, that a
manufacturer of a listed product can include it and the entire assembly is
thus listed. It would also apply to a listed assembly shop, such as Energy
Outfitters or Conergy (and there are others, of course) being able to
include it as part of a listed assembly, such as an Outback PS system.

When the inverter OEMs say that "they can't recommend any lightning arrestor
because none are UL listed", you're supposed to listen between the lines.
Most manufacturers would prefer to see surge protection on their equipment.
Outback even requires DC surge protection in a system in order to cover
lightning damage as part of their MX60 warranty. The product goes in after
inspection. You didn't get this from me, though...

Allan at Positive Energy

-----Original Message-----
From: Kirk Herander [mailto:kirk at vtsolar.com]

The Delta brand of arrestors, such as the LA302R (ac) and the LA602DC do not
have a standard "UL" mark but rather the backwards "UR" mark. I understand
this mark is for listed individual components and not stand-alone 


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