Zapped through the aerial cable!!!

[2cvbloke]

I was splitting the aerial cable today so I could use my OnDigital box in my bedroom without the use of my useless rabbit ears aerial, but once I had got the original downlead connected back up and tested the signal in the living room, I went back up to the splitter and touched it to grip it when attatching the bedroom cable and I got one hell of a zap (not painful but enough to cause my arm to jerk back and whack the window frame, well when it hit the frame it DID hurt!!!), so I went downstairs and unplugged the aerial cable from my oggle box and saw a small spark which is making me wonder where the electricity is coming from as there shouldn't be any current in the aerial at all!!!

Other than that shock everything's all working properly and I have a nice clear picture (both analogue and digital) in my bedroom...

 

[Analoguesat]

Its normal for tv and video equipment to "float" at about 40-50 volts. Its because everything isnt individually earthed these days, but is double insulated.

 

[2cvbloke]

Its normal for tv and video equipment to "float" at about 40-50 volts. Its because everything isnt individually earthed these days, but is double insulated.

Should I earth the cable from the splitter then for safety? It's one of those metal cased ones used for cable TV/Broadband distribution rather than those cheapo white things so not difficult to do...

 

[Analoguesat]

You will have to wait for someone with more electrical knowledge than me to answer that one.

 

[2cvbloke]

You will have to wait for someone with more electrical knowledge than me to answer that one.

Okeydokes...

Oh, just noticed your badge is a red X...
Another one to find....

 

[Analoguesat]

The badges under my nick look ok here. Theres 4 red XXXX's on the avatar

 

[2cvbloke]

The badges under my nick look ok here. Theres 4 red XXXX's on the avatar

Yeah, but I remember something about the badges once being stored in a Moderator-only section (and some still are by the looks of your single red X), so us non-mods can't see what you're seeing...!

 

[2cvbloke]

See? That's all I see!!! O-Ha

 

[PoloMint]

A slight shock from an aerial or metal part of a receiver/VCR/DVD player isn’t unusual. As Analoguesat says most of these boxes aren’t earthed, and so have a ‘floating earth’ that can be 50v or so different to ‘proper’ earth. However the current is tiny – so it’s harmless (in theory). Also if you have one unit earthed (such as an amplifier) this will normally be enough to prevent this in all connected devices. I believe the lack of earthing can be a problem in big communal systems when the entire system is not earthed and allowed to float – until someone touches an aerial and it’s all drained through them. I think that’s why they are earthed – maybe someone will correct/confirm this.

One problem with having all devices earthed, especially aerials and devices on different power lines, is it can cause an earth loop, resulting in a very annoying background hum on any sound equipment. (Most easily resolved by cutting the earth line to the amp, destroying the loop, and destroying the earthing to the amp – not recommended).

This really doesn’t answer your question about earthing it 2CV, take Analoguesats advice and wait till someone with proper electrical knowledge comes along...

 

[rolfw]

Not really my field either, but on communal systems, you also have the interphase potential of 400+ volts I believe, so earth bonding is a must.

 

[2cvbloke]

Some smartie edited my last post!!!

Anyways, if I ground the splitter do you think I would get the Humming you mentioned or would it be minimal enough to go un-noticed?

 

[PoloMint]

Ahh I knew I was forgetting something about communal systems.

I once had a network to a neighbours house, after about a year I found out they were on a different power phase to us, still I think the earths of the houses were connected...

2CV – only way to know about the humming is to try it and see. Another problem with earthing aerials is it makes them even more attractive to lightning...

 

[2cvbloke]

2CV – only way to know about the humming is to try it and see. Another problem with earthing aerials is it makes them even more attractive to lightning...

Ah, lightning, erm, I think I'll put up with being zapped with 40-50 volts than 40 to 50 thousand volts!!!

 

[PoloMint]

Yea, even without being earthed an aerial is probably still more attractive to lightning than the brick wall it’s mounted on.

 

[Analoguesat]

Yea, even without being earthed an aerial is probably still more attractive to lightning than the brick wall it’s mounted on.

That strike has just jumped through about 10 miles of air. 40 feet of brickwork damp from the rain isnt going to stop it!

 

[Analoguesat]

I dunno what you are complaining about 2CV - when I was a handyman in Yorkshire 20 years ago I regularly used to get 240V through me changing the bulbs around the field centre. Never did me any harm!

Apart from making my heart race a few times.......!

 

[misterminibus]

my echostar has a 2 way split on the rf out and I regularly get a shock from it...it does me no harm and the sat box works fine with it too has done for over a year.....I say if it aint broke dont fix it... especially if like polomint says its more attractive to thor the lightening god.

 

[PoloMint]

That strike has just jumped through about 10 miles of air. 40 feet of brickwork damp from the rain isnt going to stop it!

Yea the damp wall won't stop it, but anything metal on or near the wall will attract some of it, the better earthed the metal, the more it will attract.

But a tiny earth wire would vaporise instantly, along with the aerial cable, leaving your TV and most things connected a smouldering mess. But there's no way of avoiding this, if the aerials not earthed TV will still go, even if the aerial is earthed to a lightning conductor (which isn't good for reception) the TV will take enough of the hit to write it off. Unplugging the aerial in an electrical storm and keeping the end well away from anything electrical is one preventative measure, but again that messes with reception (but the electrical storm itself will cause some interference anyway).

Anyway a bigger worry is the power lines being hit, much more likely to happen, and would probably damage a lot more that just the TV equipment.

A friends telephone line was once hit, they were out at the time, when they got back they said it looked like a bomb had gone off in their home office, but it was just the fax machine exploding... The phone company denied and denied it could be because of a hit to their lines, then accepted and coughed up some cash.

 

[2cvbloke]

I dunno what you are complaining about 2CV - when I was a handyman in Yorkshire 20 years ago I regularly used to get 240V through me changing the bulbs around the field centre. Never did me any harm!

Apart from making my heart race a few times.......!

I was once shocked whilst up a set of stepladders near the top of a staircase and nearly fell down, beat that!!!

 

[spiney]

As I keep on saying, this arises because sat receivers are class 2 elextrical equipment. Double insulated with no earth, so theoretically safer, but you can get "tingles and small belts".

http://en.wikipedia.org/wiki/Appliance_classes .