Protection against lightning without grounding

[Jumpion]

1) I was wondering how you would protect the following setup against lightning:



The following devices are going to be connected to the PoE switch:
- one indoor camera
- two outdoor cameras (obviously more susceptible than the indoor camera)
- three PCs

The PoE switch is going to be connected to a power outlet that unfortunately doesn't have grounding, so only the line and neutral line are connected to the switch. (there is grounding available in our house, but I believe only in the bathroom and kitchen)

2) I was also wondering which devices would possibly be damaged by lightning if you set it up without any protection.

3) My last question is which type of cable is sufficient to the setup above. I'm doubting between cat 5e shielded vs unshielded.

 

[aristobrat]

I would imagine anything connected to the switch is potentially at risk, but I’m still learning this.

I have two UniFi Poe switches that are connected to grounded outlets. I have nine cameras (using unshielded CAT6) connected directly to them (no patch panels or anything before them), and both switches appear to sense ESD on the cables when there is lightning in the area and will kill the power to the ports.

The other day, there was a lightning strike 7 miles away (according to the Weather Underground app), and the switches sensed it.

This is making me want to replace my lines with shielded cable/terminators...

@TonyR might have some better input!

 

[Jumpion]

@aristobrat

Thanks for your great input.

After reading your experience, I think I'm going to purchase the shielded cat 5e version. Still remains is my grounding issue. I believe the shield has no effect if the PoE switch isn't grounded, right? So, I have to solve that problem first...

Question @aristobrat, I was wondering how your PoE switch sensed this lightening strike? Did it damage its fuse or even worse? Off topic: That might me thinking that placing a lightning detector is not a bad idea at all (just out of interest, not to protect my devices).

 

[TonyR]

My PC, and power brick for DSL router, 8 port switch and indoor Unifi access point are all on a TrippLite UPS with 3 prong grounded plug.

The DSL phone line coming into modem is on a TrippLite surge strip using its RJ-11 protection, strip has 3 prong grounded plug. It has given itself up twice in 8 years (cost is $8).

I have one Ubiquiti ETH-SP on the patch cable feeding the switch coming from the DSL modem.

The one camera that is not on or in the house is mounted about 60 feet away and inside a bluebird house. I got it all together too late for this nesting season due to health issues. I use the below schema to protect my LAN; not concerned too much for the birdcam, a $25 TOP-201 720P cam with RTSP and external IR. Essentially the only STP (Shielded Twisted Pair) is Ubiquiti ToughCable Pro CAT-5e with shielded RJ-45's and it runs from ETH-SP to ETH-SP. Both ETH-SP's are grounded with their own driven ground rod. Going into the house and up to the birdcam is an outdoor-rated, UTP (Unshielded Twisted Pair) CAT-5e cable. I don't run shielded into the house in this instance, as 60 feet is a pretty good 'lightning rod' and I hope to arrest it on 1 or both ends of the STP where the rods are driven and keep it off my LAN.

I fully expect some folks to jump up and down about 'ground loops' but there are no currents drawn from either rod in this 12VDC, low impedance, twisted pair system and it does not electrically or physically touch any neutral or ground buss in my house. The cam is sourced from the house with a transformer-isolated, low voltage DC source and isolated from both driven grounds. If you disagree with what I have done here I highly recommend you do not incorporate it!

For the record, when I know there's an incoming electrical storm, I unplug all kinds of stuff. I've seen lightning go thru UPS's and suppression devices like it was a straight wire. The protection is for the times one sneaks up on us, out of town or I just plain forget (brain farts at my age are common).



Ubiquiti ETH-SP

 

[aristobrat]

@Jumpion, I’m guessing trace amounts of ESD must have traveling over the camera Ethernet cables and these Ubiquiti PoE switches are sensitive to it. IMO, I haven’t had a lightning strike anywhere near close enough to cause any damage to the equipment, so it’s irksome to me that the switches “proactively” drop power to the PoE ports so easily. I’ve run other PoE switches through thunderstorms (attached to the same cameras/cables) and they had no issues. I’ve also tested with the cameras split between the two Ubiquiti switches (and both switches will both react to lightning). If I have all of the cameras plugged into one switch, just that one switch reacts to lighting... the other switch keeps on working fine while the storm is happening.

All of my cameras are directly attached to the soffit that runs around my house... I’m not doing a run across the yard like @TonyR I thought I’d only have to worry about direct lightning strikes, so I went with unshielded cable (as I didn’t imagine shielded would offer much help in that situation).

In hindsight, .. a lot of the soffit around the house is wood with a white metal flashing/trim wrapped over it, so maybe that’s acting as a big conductor for ESD?

 

[Jumpion]

@TonyR and @aristobrat Thanks a lot for your help. Very nice schematic, and thanks for sharing your photos!

@aristobrat, Very good question, I was also wondering if your house is more sensitive to lightning than houses of stone for example...

The majority of houses in the Netherlands are constructed out of stone. In our house, the first and second floor (so ground level and the one above it), are from stone. The roof is constructed out of wood. I want to attach two outdoor cameras to the wall (approximately two meters high, around six feet), see a picture of my house below (red spot is the place where the camera is going to be attached):



@aristobrat, am I understanding correctly that you don't have a surge protector? Basically, you are running the same setup as the picture in my first post, right?

Off-topic:

I read some topics about computers that are connected to no-grounding outlets (so only line and neutral), and whether this is bad or not. (obviously is is bad, but how bad) It looks like the opinions differ among the people in the Netherlands. It would have been simple if all the rooms had a grounded outlet, but unfortunately it is limited to the bathroom and kitchen in the majority of houses. My computer is not connected to earth and has not given it up yet by a lightning strike. They advise to disconnect your devices when there is thunder, but I don't do it.

When I worked in an electronic production company, I remembered that the boss bought a couple of adapters that he placed in the wall outlets that weren't grounded to protect the engineer from electrical shocks. I should ask him about this adapter and it might be worthy to place such adapters in my outlets as well.

 

[aristobrat]

@aristobrat, am I understanding correctly that you don't have a surge protector? Basically, you are running the same setup as the picture in my first post, right?

Right. I have no surge protection on any of the ethernet cables that run to the cameras. I'm running basically the same setup as your picture.

 

[TonyR]

When I worked in an electronic production company, I remembered that the boss bought a couple of adapters that he placed in the wall outlets that weren't grounded to protect the engineer from electrical shocks. I should ask him about this adapter and it might be worthy to place such adapters in my outlets as well.

That is likely a GFCI device that monitors the currents on the hot (black) and white (neutral); if what's on the black exceeds what's on the white by a tiny amount (usually less than 5 milli-amperes) it will trip. That's because it 'thinks' that the voltage being supplied by the black is not returning 100% on the white as it should but that some is going where it should NOT...like through a person to the earth or some other undesirable return. This is especially important if there is no protective (green) earth ground (no third prong).

By design that's all it does...it's not designed to guard against surges or ESD.

 

[TonyR]

@Jumpion I’m not doing a run across the yard like @TonyC.

Whodat? Dis here is @TonyR

I thought I’d only have to worry about direct lightning strikes, so I went with unshielded cable (as I didn’t imagine shielded would offer much help in that situation).

I don't plan on ANYTHING helping with DIRECT lightning strikes. Around here, it's a waste of money. Also, they don't happen as often as the nearby strikes that induce gobs of static onto conductors of any kind. That's what the shielded and grounds are for...the ones that I might be able to mitigate damage from.

 

[aristobrat]

Essentially the only STP (Shielded Twisted Pair) is Ubiquiti ToughCable Pro CAT-5e with shielded RJ-45's

Did you use Ubiquiti's shielded RJ-45? If so, did you use the one with the ground strap attached to it?

 

[tangent]

If you want you can do a whole house lightning protection system with spikes on the roof and a ground ring all the way around the house. There's still no guarantee your devices would survive and they would still need additional surge protection devices. Generally most surge protection devices require a good ground connection to function.

You can also "air gap" part of your network with fiber optic cable.

 

[aristobrat]

I'm not too worried about a direct lightning strike, ... that is what it is ... but with my PoE switches being able to sense ESD from lightning strikes miles away, I'm definitely interested in understanding that aspect of grounding more.

 

[tangent]

I'm not too worried about a direct lightning strike, ... that is what it is ... but with my PoE switches being able to sense ESD from lightning strikes miles away, I'm definitely interested in understanding that aspect of grounding more.

Here's a post from last year with some links.

I've never really delved that deeply into it, but here are a few links that might be useful:

http://www.ul.com/wp-content/uploads/2014/04/LightningProtectionAG.pdf
https://pdhonline.com/courses/e367/e367content.pdf
NFPA 780: Standard for the Installation of Lightning Protection Systems
Is Your Lightning Protection System What It Should Be?

 

[TonyR]

Did you use Ubiquiti's shielded RJ-45? If so, did you use the one with the ground strap attached to it?

Negative, used the barrel crimp, below: