[RE-wrenches] Delta LAs

[R Ray Walters]

You could buy several ground rods for the cost of one Delta.
Ground Impedance is the real issue. Both the Delta and the Polyphasor need a good ground to work.
While I haven't seen much of a correlation between Deltas and reduced lightning damage, (lots of system damage with and without)
I have found that well grounded systems (tied to a steel cased well) have never had a problem, even with direct strikes to a wind turbine (did lose the $40 turbine rectifier, but nothing else)

I now own a clamp-on ground impedance tester, and the results were miserable. Some electrodes were over 800 ohms to ground! (code requires under 25 ohms)
I'd spend more time and money reducing ground impedance, and then if it makes you feel good inside, throw the little "lightning faeries" in, if the AHJ isn't looking.......

If its really lightning country, and a really expensive off grid system, I use Polyphasor, but they have their own issues. (very expensive, no UL listing, loose internal connections, nuisance tripping, need a large J-box to mount them inside, etc.)
I haven't tried the Citel stuff, but it looks to be listed, and mounts on a DIN rail. After installing a couple hundred Deltas, I'd try something else at this point.


R. Walters
ray at solarray.com
Solar Engineer




On Sep 14, 2010, at 10:22 AM, Kristopher Schmid wrote:

> My thought here is that nothing will protect the equipment from a direct strike, but a near strike that may induce a significant surge may be absorbed by the LA and protect the equipment.  I like the feedback so far.  It would not break my heart to stop using them altogether.:-}
>  
> Kris
> Legacy Solar
> 864 Clam Falls Trail
> Frederic, WI 54837
> 715-653-4295
> solman at legacysolar.com
> www.legacysolar.com
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of August Goers
> Sent: Tuesday, September 14, 2010 10:39 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Delta LAs
> 
> All -
>  
> I guess my thought is a little off topic, but are lightning arrestors even worth using at all? My logic has always been that if lightning does indeed strike that it's likely going to blow the arrestor and and inverter. We don't have much of a lightning issue issue in the Bay Area so I don't have any direct experience.
>  
> Best,
>  
> August
> 
> On Tue, Sep 14, 2010 at 6:29 AM, Kristopher Schmid <solman at legacysolar.com> wrote:
> It is quite ironic that just a week after I posted a question to the group
> on testing the integrity of lightning arrestors, I had one apparently faulty
> out of the box.  The manifest of this was interesting: when the AC LA
> (LA302R) was connected in parallel on the AC input to a SB3000 inverter,
> there was 125vac neutral to L1, 125vac neutral to L2, and 1Vac L1 to L2.
> SMA tech support suggested the LA as the issue and sure enough, it was.
> Attempting to test good and faulty arrestors with an ohmmeter gave the same
> result - off scale open.
> 
> Any thoughts or comments from the group?
> 
> Kris Schmid
> 
> Legacy Solar
> 864 Clam Falls Trail
> Frederic, WI 54837
> 715-653-4295
> solman at legacysolar.com
> www.legacysolar.com
> 
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