Protecting grid tied equipment from lightening strikes / surges on the grid

[clivejo]

Just wondering how other people protect their valuable grid tied equipment from surges on the grid, say from a lightening strike.  I recently had a cordless telephone blown to bits after a lightening strike and associated spike on the telephone line! 

How do you protect yours?

[rogeriko]

I think the telephone line is the main problem with lightning strikes not the electrical grid. Everything connected to the telephone line constantly blows up everytime there is a thunderstorm here but not electrical equipment disconnected from the phone line, Maybe the grid is so big it just absorbs the power whereas the phone equipment is all very low power and sensitive electronics.

[wesnet]

We used to try to protect all our exchanges with lightning arestor discharge tubes across the extention and line pairs, these were three pin with one pin to earth. There is one fitted to the BT incoming socket in most installations but it only reduces a surge voltage between the incoming pair so is next to useless.

See these sights for some ideas

http://www.britishtelephones.com/lightng.htm
http://www.satcure.co.uk/tech/phonesurge.htm

the main point to be remembered is that you need a good earth and if the line is struck directly there is nothing that will protect you.

John

[clivejo]

Can you get insurance to protect yourself against the damage done by a lightening strike?

[offthegridandy]

 I was v concerned when I installed our PV (1.6Kw) 4 yrs ago but could get no info from UK suppliers. General comment was "we don't do that"  Well as it was my money I figured some protection would be good.  I ran HD earth cable with terminals bolted to each panel then down to proper ground rod.  I used a seperate earth rod due to distance from power houser, all other equip and house shares common earth point.

Available in USA is this http://www.deltala.com/products.htm do a whole range of lighning arrestors, capacitors for DC and AC.

reccomendation is/was

LA 302 a/c arrestor for out put from invertor
LA 302 a/c arrestor for genny output

LA32 DC arrestor DC input to charge controller
CA 302R surge capacitor for a/c output from arrestor

Guys at Delta were very helpful and I don't work for them.

Andy

Also read the article on this link for the US code on grounding  http://www.nmsu.edu/~tdi/pdf-resources/cc72.pdf

[biff]

during an ice storm(for want of a better description) our turbine had zig zags of lightening running along the tail to the alt before it went into a stall,
  it was not like a big strike coming down from the sky even though that had happened a  few moments earlier some 50 or so mtrs to the rear of the turbine so i recon the whole ground area round the turbine became live.maybe thats why it affected the symmetra and the new generator plus the sound on our flatscreen which came back on later.
  i had never seen lightening like that before.it looked like someone was up welding the top of the turbine,the same blue flashes but zig zaging along the tail..really weird. i knew it was serious when the turbine went into a stall.i dont think there is anything i could have done to protect the equipment if the ground became live.hard to know.
                             biff

[Ivan]

The only way of protecting a PV system from direct strikes that I'm aware of is to NOT put any earthing on the framework - any earthing will serve to ATTRACT lightning - which is always looking for the least resistance path to earth.

[knighty]

The only way of protecting a PV system from direct strikes that I'm aware of is to NOT put any earthing on the framework - any earthing will serve to ATTRACT lightning - which is always looking for the least resistance path to earth.

I was thinking the same thing... much better off with a lightening rod above the panels... to attract the lightening away...

not that I'm advising that.... I don't know if that's a good idea either....

haven't head about any lightening strikes on panels so I doubt it's much of a problem ?
(they should be covered under your house insurance if you have it too!)

[skyewright]

haven't head about any lightening strikes on panels so I doubt it's much of a problem ?

I don't have any details (aside from the location) but I was told that an off-grid installation here on Skye took a hit in a December storm and lost the inverter.

[offthegridandy]

Biff, I think your probably right with lightning as you describe, ain't nothing going to protect it.  The tallest thing here is the "all metal" turbine tower, I'd rather hope that that took a wack than the ground mounted PV panel array.

Andy

[rogeriko]

Freind of mine lost a studer inverter when the lightning struck the telephone pole at the bottom of the garden, went into the ground and entered the garden lighting cable, buried 30cms deep near the base of the pole, and through the mains cable to the inverter. I dug up the underground cable to find it was all melted into short pieces.