Help, Mount CCTV on lightning arrestor tower

[ben_indo 0]

dear all;

 

I got quite challenging project, the project require us to mount cameras on a 18 meter high tower, the tower is design for lightning arrestor with the main grounding conductor lay inside the tower.

 

I am very concern about this setup for the camera got fried as its too close to conductor

 

Any ideas what shall we do to minimize the chance of camera getting fried

 

Thanks

[cglaeser 0]

I am very concern about this setup for the camera

 

Concern for the camera? What about concern for people? You need a qualified professional to do the installation. If lightning hits a camera, it will fry, so steps must be taken to reduce the odds of the camera getting hit, but the real concern is making sure the energy is routed to ground and not to other equipment and people who may be using that equipment.

 

Best,

Christopher

[Soundy 1]

We installed a number of cameras on a tower about that height. Unlike your instance, the tower was installed specifically for the cameras, but it does have lightning protection: there's a lightning rod that extends a good meter-and-a-half above the highest camera, and is bolted directly to the steel tower. The tower itself is then grounded at the base (heavy-gauge copper wire clamped to the tower, and to a plate buried 7' deep beside the concrete base).

 

Three years in service now, not a single fried camera... good thing, too, since three of the four are FLIR thermal cameras worth a combined $50,000.

[ben_indo 0]

dear soundy, your picture tell thousand words, thanks

christopher, thank you for your concern, the cameras are to be mounted at around 5 meter below the lightning rod, the lightning rod will connect to ground with heavy copper wires

[tweak'e 0]

one of the problems with lightning is that it raises the ground potential so lightning will often look for another path ie through the cameras.

 

all ican suggest is to not make the camera stick out on its own, keep it close to the structure. hopefully their lightning conductor is nice and straight.

you can fit AV surge protectors at camera, mayby at the bottom of t he pole where the cable will go across to the building and dvr end. try to keep cables straight and the earths nice and straight. also isolators will help.

the power supply side gets a little tricky i would try to isolate it as much as possible and fit lighting protectors.

 

the last thing you want is have lightning travel back down your power and video cable and set fire to the building etc.

 

i've had a few places where the tv aerial has been hit and very lucky not to have set the place on fire.

[cglaeser 0]

your picture tell thousand words

 

Here are a few more words on the subject

 

 

As shown in the photo, lightning will strike the lightning rod and travel straight to ground, or just flirt with the tower and hit something nearby. The important thing is to make sure you hear a loud bang; that's nature telling you that you are OK.

 

On a more serious note, you need to arrest the potential surge in the cables from the camera in the event the camera is hit. I don't think this is a DIY project, but if you insist, then Google is your friend.

 

Of course, a lot depends on where you live. I grew up in Florida, where it is wise to have a healthy respect for lightning. We lost several trees near our home in separate storms over the years, and my brother's house was recently hit and the lightning blew a $5,000 hole in the roof. I now live in northern California, where thunderstorms are rare.

 

Best,

Christopher

[Gator 0]

I think you should pass on this job. To do this correctly will be very expensive. You would need to construct it similar to a cellular tower installation. Everything has to be bonded to everything else. You need to bond the tower, shelter, video, camera power, power for the monitors etc. All of it needs to pass through a bonded ground bulkhead. Video and power will need arrestor devices and surge suppressors. Everything has to be connected to everything else so that differences in potential won't exist when you take a direct lightning strike to the tower. The ground resistance may be 10 ohms in good soil. A 50,000 amp hit will produce 500,000 volts. If the tower, shelter and people are all enclosed at that same potential they are safe. If there's a mistake somewhere in your plan, you can get lethal potentials between various items.

 

Chances are you will lose the camera anyway because of the electromagnetic impulse. An approach that may work is to protect the tower with static disipators. Those are like a porcupine of wires attached to the top of the tower. The discharge the static from the atmosphere so potential doesn't build high enough to cause a strike. Some are very effective at avoiding strikes. I wouldn't consider it adequate for protecting life as a substitute for bonding and grounding.

 

You can find some examples on emerald-wireless. Click on their links for grounding and the other link for coax. Does your client have the budget to do this job correctly? If not, don't get involved.

There is a chance for loss of life or the facility if this is done incorrectly. The design should be reviewed and approved by an engineer who routinely does this kind of work.