Detached garage grounding

[mikefamig]

The reason I am so interested in this conversation is because I DID lose an ethernet switch to a lightning storm a short while ago. I looked at my sub-panel in the detached building and I do have a ground conductor between the main load center in the house and this sub-panel. I also have good ground rods at each building and the neutral is isolated from ground at the sub panel.
 
I installed surge proctors hoping to prevent future lightning strikes from harming equipment but I would love to learn if there is anything more that I could do short of converting to fiber optic.
 
Mike.

 

[pete_c]

I have not lost an ethernet switch due to lightning in current home(s). 
 
I did lose a couple of network hubs in the older home due to lightning one day.  (well and one PC).
 
That said I have multiple network POE connections to peripheral edges of property which has been live now for a few years and still working just fine.  (IE: IP cams look at each other).  I overdid it a bit using one run per of PVC in to weatherproof boxes on each end and burial catXX inside.  Unless a ground hog has eaten the PVC I am guessing that the chases are intact. (the chases are now over 10 years old)
 
I did add a second from main panel surge protector to the outside AC compressor after what I assume was a lightning strike taking out the AC unit a couple of years back and causing an electrical debaucle on the main fuse panel which only tripped main breaker fuses and burned out the rest of what I had in Insteon switches at the time.  I should have taken pictures in that I did hear a muffled loud sound.  Ran outside in the rain and did see a sight to behold.  Next day looking at the compressor, all of the electrical had fused / melted together like in the old movie Philadephia Experiment.   No HVAC for a few days was very low on the WAF and I ended up purchasing a window AC unit for the master bedroom to use for about 4 days or so. (temps at night had been in the 90 ° F plus range that summer)
 
It is said that this mini surge protector will protect the unit. 
 
I have lost two irrigation controllers to lightning and in FL lightning has just tripped the fuse to the irrigation controller and I have replaced it a few times.  The irrigation controller has never been damaged.
 
Older retired folks in FL just run around and unplug everything when there is much lightning.  Just something that I have seen there.
 
I did take some pictures and posted them here.  It was a PITA / time consuming but easy to rewire the outside stuff.
 
I do not know right now if it would protect the outside AC compressor but installing it gave me a warm and fuzzy.

 

[mikefamig]

I've read over the NEC code and it clearly states that both builds must have a ground rod driven. I found an IAEI post, which has pictures showing my current setup per NEC 2005 code. The catch is there can be no other metallic paths between the buildings. I could run fiber for network, but that leaves me stuck on the security side. I could forgo the OmniPro expansion enclosure and just home run a few zones, but I feel like I am fighting the inevitable.
 

 
It looks like the best/correct answer, which is what NEC 2008 requires, is to just run a new feeder with 4 conductors. I'm going to follow NEC code and leave the ground rod connected at the shop. I also will need to rewire the shop panel so the neutral and grounds are separated.
 

 
After looking at the below picture it makes sense that with 3 conductors between the buildings ethernet, security cable, etc would become a potential source for stray current to destroy the equipment. It just doesn't seem worth the risk to fry equipment over a few hundred dollars of cable. Since I do have a disconnect at the house for the shop feeder I can abandon the 4/0 3 conductor cable, install a new 125A breaker, run 1/0 aluminum 4 conductor cable, and hookup the shop panel myself. After that is working I can pay an electrician to pull the meter, remove the splice box and fused disconnect, and connect the house panel directly to the meter.
 

 
Yes this is how I understand it and I wired my garage like your second diagram of the 2008 code with four conductors except that I have PVC conduit which is not a conductor. I also have a couple of ethernet cables and a speaker cable between the buildings in a separate PVC conduit.
 
Mike.

 

[mikefamig]

I have not lost an ethernet switch due to lightning in current home.
 
That said I have multiple network POE connections to peripheral edges of property which has been live now for a few years and still working just fine.  (IE: IP cams look at each other).
 
I did add a second from main panel surge protector to the outside AC compressor after what I assume was a lightning strike taking out the AC unit a couple of years back and causing an electrical debaucle on the main fuse panel which only tripped main breaker fuses and burned out the rest of what I had in Insteon switches at the time.  It is said that this will protect the unit. 
 
I have lost two irrigation controllers to lightning and in FL lightning has just tripped the fuse to the irrigation controller and I have replaced it a few times.  The irrigation controller has never been damaged.
 
I did take some pictures and posted them here.  It was a PITA / time consuming but easy to rewire the outside stuff.
 
I do not know right now if it would protect the outside AC compressor but installing it gave me a warm and fuzzy.

 
Pete
 
lightning can enter your building on multiple paths. I think that my switch was damaged through the buried ethernet cable rather than through the AC power line but I don't know that for sure. I think this because the switch has been around for years and the lightning strike came shortly after connecting the garage ethernet cable to it.
 
My house has always had a whole house surge device on the AC load panel and after the lightning strike I added surge devices to the buried Cat6 cable. I am beginning to wish that I had used fiber instead of Cat cable but that would still leave a speaker cable in the conduit as a potential problem.
 
Mike.

 

[rsw686]

lightning can enter your building on multiple paths. I think that my switch was damaged through the buried ethernet cable rather than through the AC power line but I don't know that for sure. I think this because the switch has been around for years and the lightning strike came shortly after connecting the garage ethernet cable to it.

 
Out of curiosity did you run shielded cable between the buildings and use shielded connectors? It is my understanding that the shield will direct stray current to ground. I'll probably just run per-terminated fiber to be on the safe side.

 

[pete_c]

Yeah thinking the lightning damage years ago (1990's) to my hub came in from the phone line.  Just a guess.
 
phone line ==> modem ==> serial ports (dead) == > NIC (dead) ==> hub (dead).
 
Irrigation controller was probably damaged (guessing here).
 
rain sensor (mounted way high) ==> manifold box - solenoids (no issue) ==> 2 8 zone controllers (dead)
 
irrigation controllers == digi serial box (no damage at all).
 
I have read about same model irrigation controller that I have redesigned a bit relating to lightning surges.
 
Really though you do the best you can and cross your fingers that you can maybe circumvent all possible paths to lightning; which still can be a hit or a miss. 
 
You can manipulate the odds better today than yesterday. 
 
Nowadays fiber is cheap; that said the ROI is better.
 
A lightning strike hasn't changed in forever and is still the same as it always was.
 
Many years ago lived in a home with an artesian water system.  Water went to an underground large well or holding tank.  It was pumped to the roof water container with copper pipes and down via gravity.  The roof edges had lightning rods ever few feet.  During rain season there was much lightning.  I was afraid to take a shower during these afternoon thunderstorms even though I had not heard of anybody frying in their shower.  I do recall installing a radio antenna on the roof of a friend one day in the afternoon before the storms rolled in.  I wasn't able to finish and left the coaxial cable free coming in to the house.  Well, a storm rolled in and a friend and I had a beer watching sparks flying from the radio antenna coaxial cable some 12" to the electrical outlet that afternoon.  It was a nice little light show in his living room.  Well that and my uncle (close to 90 these days) has been strike by lightning some 4 times in his life and just burned his shoes.

 

[mikefamig]

Out of curiosity did you run shielded cable between the buildings and use shielded connectors? It is my understanding that the shield will direct stray current to ground. I'll probably just run per-terminated fiber to be on the safe side.

No I did not use shielded cable....DOH!

 

[mikefamig]

Don't ya know lightning storms are forecast here this afternoon. I hope that I haven't jinxed myself.
 
Mike.

 

[rsw686]

No I did not use shielded cable....DOH!

 
I've used shielded cable with Ubiqutiti wireless links mounted on the roof. I've had these in production for a few years and haven't had a failure yet. For the network side only ground the shielded cable at one end. Otherwise it becomes a parallel path with the building ground. If there was a fiber option to connect the OmniPro expansion enclosure I would be all set. Although from reading it seems the network equipment is the most sensitive.

 

[mikefamig]

 For the network side only ground the shielded cable at one end.

 
I can't do that because I have no shield on the cable.
 

Otherwise it becomes a parallel path with the building ground.

 
Doesn't the 2008 code state that you can have pipes and other conductors between the buildings as long as you have the fourth ground conductor on the service to the sub panel and isolate the neutral from the ground in the sub panel?
 
I have other conductors between the buildings including a speaker wire from the Elk security panel, cat6 carrying rs-485 signal for the Elk and cat6 for ethernet.
 
Mike.

 

[rsw686]

Doesn't the 2008 code state that you can have pipes and other conductors between the buildings as long as you have the fourth ground conductor on the service to the sub panel and isolate the neutral from the ground in the sub panel?

 
Yes you are correct.

 

[rsw686]

I'm wondering it the ELK-950 will work with the OmniPro panel to protect the A/B data lines. It should since it is just surge. I'll probably pick one of these up as well. Figure more protection can't hurt.

 

[mikefamig]

I'm wondering it the ELK-950 will work with the OmniPro panel to protect the A/B data lines. It should since it is just surge. I'll probably pick one of these up as well. Figure more protection can't hurt.

I used  Ditek device to protect the Elk security system
 
http://www.ditekcorp.com/Docs/ProdGuides/LVLP%20Series%20Datasheet.pdf

 

[mikefamig]

I'm wondering it the ELK-950 will work with the OmniPro panel to protect the A/B data lines. It should since it is just surge. I'll probably pick one of these up as well. Figure more protection can't hurt.

Wouldn't the fiber to cat cable converter that Lou Apo suggested work for the Omnipro data bus?
 
http://www.amazon.com/MC200CM-Converter-1000Mbps-multi-mode-mountable/dp/B003AVRLZI/ref=sr_1_3?ie=UTF8&qid=1444355058&sr=8-3&keywords=multimode+fiber+to+ethernet

 

[apostolakisl]

On my morning run today I stopped off at a home under construction and talked to the electrician as he was waiting for the inspector.  He tells me that the standard for the last 5 or 10 years has been to tie the foundation re-bar into the ground, effectively turning the entire foundation into a single grounding rod.  Of course, two separate structures would not want to have their foundations tied together or you would be back in the same situation.