Earthing on a communal satellite dish

[Terry Charters]

Is earthing on a communal satellite dish a legal requirement?

 

[Lucid]

Not sure about the actual dish, but certainly on the distribution system that the LNB output connects to.



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[Terry Charters]

Thx for the reply Lucid. Any idea where i can find documentation for this?

 

[Lucid]

Since it's meant to be carried out by a qualified electrician as a separate service to whatever the aerial/satellite installer does, then it should be covered in the latest edition of the NICEIC Electrical Wiring Regs. I think we're on the 18th edition at the moment

https://www.niceic.com/media/news/niceic-18th-edition-wiring-regulation

If this or any other reply was helpful to you, then please do the decent thing and click the T-H-A-N-K-S button. It appears when you hover the mouse pointer near the Quote Multi-quote buttons. It costs you nothing. This is the proper way to show your thanks for the time and help someone gave you.

 

[Terry Charters]

Thx Lucid

 

[Lucid]

Thx Lucid

Yeah. Very nice. But click the Thanks button.

THAT'S WHAT IT'S THERE FOR.

 

[ericmark]

I would say it depends where it is fitted, but in general you do not earth aerials. But a dish is often mounted lower, so could be earthed, but the supply is normally clashed as SELV (separated extra low voltage) so it would not be earthed.

The problem is electrical storms are attracted to nearest earth, so to earth means more likely to get a lighting strike, with the long wires used for ham aerials this can be a big problem so a set of resistors and a spark gap is used to leak away voltage so when we reconnect after an electrical storm we don't get a shock from the build up of static.

Since you say "communal" it would depend where it is mounted, who could touch it, and what it is connected to, I would normally not earth but not cut and dried.

 

[winston1]

Communal systems must be earthed or bonded. If they are not a fault at one sub that put 240v on the cable would send that 240v to all the other subs.

 

[ericmark]

Communal systems must be earthed or bonded. If they are not a fault at one sub that put 240v on the cable would send that 240v to all the other subs.

Not so sure with satellite, but with simple aerials the aerial is NOT earthed, the distribution amplifier may be earthed, but not the aerial, normally there is a filter or braid breaker

both stops out of band signals which could swamp the amplifier/splitter and any atmospheric voltage going down the line, if you earth an aerial it will not work, and it will also increase the likely hood of a lighting strike.

You could earth a false ground plane, the aerial would still work, but it would still increase likely hood of a lighting strike.

As to a satellite dish in the main they are not where a lighting strike is likely so you could earth it, but only the LNB would need an earth to stop a fault in one output transferring to another, and I don't think the outputs are linked anyway. And for a communal system the dish outputs would be fed into a distribution unit and if any earthing is done it would be to the distribution unit not the LNB or aerial.

I have seen the result of earthing an aerial, all that was left was a row of copper beads on the ground, to earth an aerial you would be looking at a cable size of a lighting conductor, as that is what it would become, this report for churches says 8 mm diameter rod, that's around 50 mm² so the earth to aerial would need to be size of welding cables.

P.S. the circuit is not mine, it was the old radio investigation service pre digital became DTi not sure what called now, so it has come from a UK government department.

 

[winston1]

Domestic TV aerials do not have any filtering circuitry like that, at best they will have a balan. The coax is connected to the driven element which is often a folded dipole clamped at its midpoint (zero voltage) to the aerial boom which if earthed as recommended does NOT stop the aerial working.

Whether earthing it attracts lightning is another matter but earthing it will certainly prevent the aerial system from rising to unhealthy potentials with nearby lightning.

 

[ericmark]

Domestic TV aerials do not have any filtering circuitry like that, at best they will have a balan. The coax is connected to the driven element which is often a folded dipole clamped at its midpoint (zero voltage) to the aerial boom which if earthed as recommended does NOT stop the aerial working.

Whether earthing it attracts lightning is another matter but earthing it will certainly prevent the aerial system from rising to unhealthy potentials with nearby lightning.

I would not consider a "Communal satellite dish" as domestic, it may feed domestic, but would consider the dish to be commercial. There are two types of aerial sockets, those with capacitors to stop DC used for connection direct to aerial, and those without used to connect to a booster, the latter I find are hard to find, required with the old Sky magic eyes, and with mast head amplifiers were DC is sent up the coax.

note the circuit board and components this is common, the combiner in the loft would likely be earthed, but not the aerial.

 

[winston1]

Those are not aerial sockets, they are unscreened rubbish. Never use those, they let interference in and will radiate if on a frequency translated communal system.

Capacitors are not required on a direct aerial. They are used on communal systems if not earthed to prevent fault voltages from one property to another.