Why are dishes not earthed

[rolfw]

Yes the lnb would have been ok if you did earth it, If some one else installed the dish for you you can claim a replacement lnb from them as the installation was not done correct,

All lnb feeds cables should be eathed useing a ground block,

I disagree there RD, as the LNB would be wiped out before anything got to the earth bond, that is simply there to offer marginal protection to the inside equipment.

 

[2cvbloke]

Wouldn't surprise me if sky suddenly deemed LNBs to be a consumable alongside the likes of batteries....

 

[dxsat]

With global warming, this kind of event is probably going to be more common.
In the space of 10 months, from two lightning strikes near to the house, I've lost:
A nearly- new Pace Sky+ Digibox
An ADSL wireless router
A quad Invacom LNB
Two power supplies
We are 3000 feet up in the mountains just outside Madrid, near the top of a hill. I am now taking this problem very seriously. I did the installation myself, and had not even thought about lightning before.
My power supply to the digiboxes is now a UPS (Uninterruptible Power Supply). These come with surge protection for both telephone and power lines. I would recommend one of these to anyone in parts of Europe with unreliable electricity networks, or a weak Astra 2 north beam signal.
When I came to replace the LNB, one of the cables was blackened near the F connector. I am still trying to work out where the main surge came from, either the ground or through the mains. the first strike was probably passed by the phone line, as it blew the router and the Sky+, which was connected to it. (I use VOIP for Sky box office)
If the best opinion is to earth the cables and LNB, then I'll do it straight away, there are still storms about.

 

[PoloMint]

I agree with Rolf, I really don't see earthing the LNB as doing much to save it.

Unplugging everything in a storm is the best option IMO, but not always practical I know, and won't do much for the poor LNB.

Everything else is might reassure you and offer some protection, but don't count on it. UPSes aren't even that reliable with a direct hit to the power line, however but the makers might offer some insurance on damaged equipment connected to the UPS.

 

[dig deep]

U can´t secure the LNB´s from the EMP
(well, U can if U hide them inside a bottle covered with thin foil)

So, U better pray next time Thor visits Your area

 

[Zorba]

A couple of weeks ago,during a thunderstorm,a customer had a direct hit.The lightning hit the tall aerial pole which had two antennas on it.The aerial mixer blew apart,and the cable burnt apart.The aerial cable,and satellite cable came down through a (plastic)pipe from the roof down through the walls.There was an outlet on the wall where both cables pass through on to the next outlet.The plastic cover plate of the first outlet blew apart and the aerial cable ended there.
The customer was not home when the lightning struck,and when she came home there was no power.After switching the power back on from the fuse box,the digibox was flashing red light so she unplugged the digibox.When I got there the next day and plugged it back in,the digibox started to smell and give off smoke.There was a dvd player under the digibox which was dead and on the top corner of its case was a small pinprick of a burn mark where a spark must have jumped across from the digibox(which was a pace 2600,shame).Also the lnb died but no marks on it.
What I can't understand is why none of these gadgets are earthed these days.Everything including the tv and video have only live and neutral in there cables.Would they have survived if they were earthed?

 

[PoloMint]

I very much doubt it. If the surge has melted plastic and cables on its way to the digibox then it's not going to peacefully travel to earth as soon as it reaches it, it'll jump and burn out most of the components it passes through.

 

[Zorba]

But it should travel down the braid which is connected to the chassis which is earthed so the electronics are bypassed.

 

[PoloMint]

I'm not an expert in this, but I really doubt that anything that melts a cable is going to pass through a box full of electronics without severely damaging it, even if not physically then wipe chips etc. I looked into this for radio a while back, even with an antenna earthed before the receiver, the receivers are still reported to be dead after a direct hit to the antenna, just not as badly damaged (no melting or fire) compared to no earthing. It might however protect connected equipment by preventing it from spreading to all other nearby devices.

 

[2cvbloke]

That's the thing about lightning damaged equipment, even if it looks ok outside (no scortch marks), it's completely fried inside...

 

[dxsat]

I had a message from Invacom this morning. LNB's should be earthed. They have earth terminals and these should be used- official!

 

[koansrc]

I had a message from Invacom this morning. LNB's should be earthed. They have earth terminals and these should be used- official!

Interesting Snap. I noticed the earth on my twin invacom c120 today ( hence I did a search and found this thread ). Did Invacom suggest any particular method ? i.e earthed as in attached to dish pole which goes into the ground, or earthed as in attached to the earth of the house electricity ? and also is the reason protection ( of the lnb ) or just good practice ?

 

[dxsat]

I don't know the exactly why they say this. It is probably something to do with equalising the potential between the dish and the ground, making it less likely a lightning charge will pass through the earthed device.
The message came from Invacom's technical director, so he should know. I earthed mine to the bolts in the concrete foundation, which would be the same as an earth rod. I doubt earthing it to the house system would be as good, but someone here may know more about it than me.

 

[Turok]

only a profesional company,i think,can do good erarthing of antenna systems,but its very expensice,if something happens maybe 3 up to 4 times in 10 years,my household insurance,must pay,and i replace the reiver,that is gone,or what ever!

4 years ago,one of my irte 1,50m crashed in strom,here in maunrains,we have normaly no proplems with storm,maybe every 7 years,and the insurance company payed everthing!

when you life near,the ocean,the salt,in the air,is the bigger problem,it destroyes the motor on the antenna!

here,normal house hold has only 55 cm.90 cm,dishes,very lonley,so better we move all to cypres and greece,the see the nice ones

 

[Zorba]

The big nice ones seem to attract the lightning . There was a storm in a village a few weeks ago,and a strike on the ground damaged quite a few digiboxes and lnb's . This area has lots of British people with loads of 3m dishes,many shared with up to 4 houses per dish.

 

[koansrc]

This area has lots of British people with loads of 3m dishes,many shared with up to 4 houses per dish.

What a coincidence how 2D signals increase ( sufficiently for 3m reception ) wherever there are "lots of British people with loads of 3m dishes". ...

hmmm, I guess there's just not enough in the Athens area right now. ;)