Virgin media drop cable / omni box distribution earthing

[RB2004]

Hi, apologies if this is in the incorrect place, posting here as there seems to be a bit of conflicting advice regarding electrical regulations and the cai guidelines in this area when it comes to tv aerial bonding.. So I was hoping I could get a tv distribution point of view about what is correct.

As I know when it comes to having tv distribution inside a house or commercial premises each output from the splitter cai guidelines are it should be bonded to the rest. But electrical standpoint is by doing so you are bonding the tv aerial turning it into a lightening rod.

Anyway, for one moment let's assume that it is correct that everything should be bonded.

Shouldn't virgin media connections at the very least be earth bonded inside the omni box? On the wall outside so like the gas, water services it is the same potential as everything else in the house?

I know vm don't do this, but all their splitters and 12v powered hdu devices have earth terminals built in, and I think I've seen photos of Comcast cable in Germany and theirs are all earth bonded.

Just came to my attention as through the outer shielding of the cable you are connected to every other house on vm network and at times I have noticed touch voltage occasionally and also read a case recently about somebody where somebody else's house equipment developed a fault and it did some damage.

I don't know about their cabinets but around here vm use pits with splitters in them, rather than everyone going back to a cabinet.. And when I saw inside that pit the splitter is not earthed, and from the photos inside the cabinets I've seen those don't appear to be totally earth bonded. So whatever voltage gets onto the line through the outer coax shielded is fed to each customer.

DialectrIc voltage is blocked via the isolator on the wall lol but that doesn't stop the touch voltage.

 

[septiclecky]

I thought Vrgin Media cables are fibreoptic not copper?

 

[Barx]

Copper up to house. Well, mine is and so is every one I've seen.

 

[Andy™]

fibre to roadside cabinets then copper / coax

 

[RB2004]

Yep fibre to cabinet then coax

There's different architectures,

Some have fibre cabinet linked to a chain of coax cabinets and from each cabinet house drop cables

And others you get a fibre cabinet with a big coax cable underground split every now again with a tap which each house connects to inside pits

But what concerned me was while the isolator blocks any voltage via the central coax core or dielectric it doesn't isolate any voltage which travels through the outer shielding, which in turn connects to the chassis of each stb.

While shouldn't be a problem with that usually it wouldn't be impossible for it to become electrified, then there is their power splitters which are sometimes used in the omni box outside the house which require voltage to operate

Lol so begs the question if although not covered by electrical regulations directly should it be bonded like gas and water inside the omni box so that cable entering your house is the same potential?

Here is the earthing I noticed they do in Germany but here they don't.

http://farm5.static.flickr.com/4135/4932045162_bfdfbd05b0.jpg

 

[batty]

But that has a metal case which i could see needs bonding. Sorry to butt in on this thread but i had a strange one the other day. A builder i work for said his son was getting a bit of a shock off a camera. Now this camera is fed through basically a phone charger so only 12 volts but if you test between the socket and the metal part you would fix a tripod to there is 90 volts. I just cannot understand how this can be. They also have a beat box which is a speaker thing and when this is plugged into a laptop you also get 90 volts on parts of this. Now this is not just on these sockets but through out the house. I think there may be a fault somewhere but its just finding it. When i go back i think a bit of investigation is going to be needed.

 

[RB2004]

All vm splitters and hdu are metal with earthing points but vm don't do any earthing

 

[steptoe]

But that has a metal case which i could see needs bonding. Sorry to butt in on this thread but i had a strange one the other day. A builder i work for said his son was getting a bit of a shock off a camera. Now this camera is fed through basically a phone charger so only 12 volts but if you test between the socket and the metal part you would fix a tripod to there is 90 volts. I just cannot understand how this can be. They also have a beat box which is a speaker thing and when this is plugged into a laptop you also get 90 volts on parts of this. Now this is not just on these sockets but through out the house. I think there may be a fault somewhere but its just finding it. When i go back i think a bit of investigation is going to be needed.

Batty, how did you find this 'voltage' ?

it may be phantom, did you use a digital voltmeter?

and what do you mean by socket? the 13a outlet? and what part of the 'socket' ?

 

[batty]

I used my loop tester and testing from the earth point on the socket to the metal part on the camera case.

 

[steptoe]

do you have an analogue tester you could try?

 

[batty]

Must have one somewhere next time i go back will test with a different meter.