Lightning Revisited [RE-wrenches]

[Ray Walters]

>
>I'm glad we are continuing the dialogue on lightning.  It would be good to 
>arrive at definitive answers to this ongoing question. >
>Drake,
>
>
I regularly service systems that are over 15 years old here in Taos,and it
is becoming clear : PV systems that ground to steel cased wells are NOT
experiencing Lightning damage. Traditional grounding methods (ie., tying
all grounds together, or bonding one of the DC conductors) appear to be
acceptable. 
However if the grounding system does NOT include bonding to a steel cased
well, and all grounds are tyed together and DC neg. is grounded as per NEC,
I have had several dangerous incidents with lightning induced surges. The
damaged list includes: 2 C40s, 2 Heliotrope CCs, 1 DR inverter, 2 SW
series, Several analog and digital meters, Diode and circuit boards on a
Kohler generator,and a Windseeker 503. More importantly, a customer
received a shock from a nearby strike while using her laptop. 
I have begun not grounding DC neg in my systems, because I have seen NO
lightning problems in floating neg DC systems so far, as long as the PV
frames are grounded. 
I would consider seperating a wind tower's ground from the main PV
equipment ground, again IF I didn't have a steel cased well. 
Also, all my other grounding methods didn't save the day without the steel
cased well: 300 ft of stranded Cu buried outside of the conduit, six 6"
steel poles in the ground 4 ft, chassis grounds, UFER grounds, 5/8" Cu clad
rods,Delta LAs, Polyphasors, etc. all tied together and we still had $1000s
of damage. 

Bottom Line:
Steel cased well = lightning protection

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