Lightning Arrestor in Action

Lightning arrestors have limited capability, but can help in lower energy situations. Bruce Roe

Yep as a Power Protection Engineer, I keep trying to tell folks that (sigh). They can help with nearby strikes and minor utility faults if properly sized, located, and installed Problem is most consumer units are Junk, and not even many sparkies (Electricians & Installers) know how to properly install them. Even if you get it right, will not do squat on a direct hit.

So why are they sold? . Because there is a Market for them and people buy them.

FWIW the best consumer units you lease from the POCO. They are what is called Meter Collar SPD. They come out and inspect your Service Disconnect (meter box) to make sure you have the proper Ground Electrode and code compliant wiring inside your Main Breaker Panel. Once you satisfy their requirements are met, they unplug your meter, Plug in the SPD Collar, then plug your meter into the SPD Collar. They charge you a monthly fee of a few bucks which is actually supplemental insurance in the event you take a direct strike with damages. It will cover what your HO insurance does not pay like deductibles and depreciation. They are simple 3-Mode SPD and each mode is rated 40 to 100 Kva for 800 usec per mode depending on the size of your service.

The best lightning avoidance device I have seen is the spike on a very tall tower which creates a "cone" of protection almost like an invisible Faraday cage.

The other type is used by POCO's where they string the ground wire above the HV wires of a transmission line. The ground wire is supposed to be hit by lightning before any of the phase wires below it gets struck. Still with the power of lightning there is no way to totally protect something from being hit or damaged.

Yep. A direct strike and you are toast. But the protection can help with induced voltages from near strikes.
Thanks for the pics, well worth the bandwidth

Dereck, would that SPD collar on the meter be something we should look into using at repeater sites? We do also (try to) comply with the rest of the codes and Motorola R56 that you might be familiar with.

Steve that is certainly a step in the right direction and most certainly one-step of a good Power Protection design. I am very familiar MR65 and other such documents. Having said that the POCO Collars TVSS are a bit light duty. If you know how to get in touch with me, do so with your email address and I can send you some documentation via email. I would say PM me here, but I digress.

One way to find me since you are a Pro, consider join Mike Holt Code Forum and reply back here when done. I will then Log in to Moderator Panel and look at your email address, approve your membership if another MOd does not beat me to it. We screen applicants. Just be sure to use the same username and a real email address. Once you are a member there, you can get all your technical questions answered on any electrical subject including Solar from pros who do it every day for a living.

DIY need not apply, for professionals and students with credentials or references

Let me know and hope that helps.

EDIT NOTE TO STEVE:

Crap Steve it just occured to me who you are and you know how to reach me. I know you kind of and you are already a member at MH. My bad. Let me know if you want the documents or call me and we can discuss. You know how to find me. . That is what happens when you get old. My daughter Amy and Jr. are doing great, hope your kids, you, and all your family doing great too along with you and all your family.

SK, I had my POCO install the SPD collar on my meter just like in your pic. It cost me $90. As the lineman was installing the SPD it appeared to me that if that device worked as advertised it would direct high voltage current directly into my main distribution panel located in my basement. I have a code compliant three wire connection between the meter and main disconnect inside my house. The path would be from meter through the neutral wire into the main disconnect, then would have to reverse direction to leave via the GEC to the grounding electrodes.

If I install a GEC from the meter directly to the grounding electrodes on the outside of the house, I then create a duplicate neutral path which is frowned upon by the NEC. I am tempted to add this additional GEC from meter to grounding electrodes since I have this device installed on my meter.

Dan you either have a misunderstanding or something wrong I am missing.

You Meter collar as you say is 3-wire from the POCO Transformer. At your meter is most likely also your Service Disconnect Device and that is where the Earth Ground to Grounded Circuit Conductor (Neutral) is made. You are also there is no other conection made between ground and Neutral beyond that point electrically. With me so far?

The SPD only has 3-modes meaning A SPD device connected between L1-N, L2-N, and L1-L2. There is no need for a 4th SPD L-G because it does not do anything if N & G are solidly bonded together or dead bolted Short Circuit. Lighting is seeking all paths to Dirt. If your N-G bond were inside your home basement means it has to come inside first before it can go back outside where it came for and looking for in the first place.

Well, I'm in the backwoods of Indiana. We do not have a disconnect at the meter. Three wire from transformer to meter...then three wire from meter to main distribution panel (ie first disconnect) inside the house.

Yes, if I move the first disconnect to the meter location then I would not have to direct over voltages into the house using the under meter SPD since I could then use a four wire connection between the meter and main distribution panel and the GEC would be completely outside the house.

For a variety of reasons I do not want to move the first disconnect. So far I have just lived with the risk rather than violate the NEC rules.

Dan the disconnect has to be accessible to the FD. That is why the Meter itself is the Service Disconnect in most installations. All the FD has to pull the meter out. Code also requires that the utility Grounded Circuit Conductor to remain Solidly Bonded even when the meter or disconnect switch is operated. I will draw something up later for for you to look at if that will help. From the meter you can go in either 3 or 4 wire, makes no difference.

No, you do not have to draw it up........I understand......pulling the meter is the Service Disconnect.

OK Dan just trying to be helpful You can ggo in the basement 3-wire, you use the UL approved metal raceway approved as the the EGC conductor. It is not a Ground Electrode Conductor or even connected to dirt once inside.

You see a lot of what you describe in homes with basements, especially older homes. Technically it complies with code, just not a good practice inviting outside inside your home. Good luck to you.

I agree it is not good practice. Almost every house and farm in my neck of the woods is wired this way when using overhead service.

Our local POCO has tried to help. They now install an SPD right on the transformer can on the pole. IMO that helps a lot in keeping excess high voltage on their lines on the outside where it belongs. Don't know the clamping rating of those devices but it got to help.

Let you in on a little secret. At the Transformer is as good as it can get as th eprimary device and the Utility gets a lot better quality than most could home owners can afford. Couple that with a Collar type meter and it cannot get any better. Only thing you can do to improve it is Point of Use strip to help add a layer of protection like your TV and Putter.

Utility grade SPD Clamping voltage and Let Through is the same as what you can buy due to UL 1741 listed equipment. If anything little better than what UL specifies. Devil is in the details. TVSS can really only protect you from utility faults and nearby minor lightning strikes. No TVSS can protect you from a direct strike unless you have the budget of NASA and they may not be enough using EMP protectors the military uses for TVSS.