Bonding TV ariels & amps

[jibjob]

Hi all,

I've been asked by a TV ariel installation company to quote for bonding a soon to be installed TV ariel and amplifier. The service will be shared by a number of flats in the same buliding. Can't find anything in the BRB regarding the regs on this.
Can anyone help/enlighten?

 

[Deleted member 9648]

Never heard of this before,the only thing I can think is that the leads from a common ariel might introduce an earth potential into each flat,so in theory the braid of each lead might require main bonding where it enters the flat!!......Impractical and I've never heard of such a thing being done before.....perhaps you should contact the company and enquire what their reasons are for asking for bonding??

 

[Martin Dawes]

Perhaps it is to dissipate a static charge? I don't think it's a requirement in the regs but it's certainly not a bad idea.

Remember, if it's a PME system then it will need a seperate earth rod.

 

[jibjob]

Just spoke to installer. He says it's a requirement in communal dwellings where the ariel and amp are used by multiple occupants. This protects each one should a fault occur with anothers equipment. It needs to be a clean earth so would need to go back to the MET or other direct route. He suggested I take a look at Confederation of Aerial Industries - find aerial and satellite installers (Confederation of Aerial Industries Limited) for further info.
Seperate earth rod if PME? Not sure if I understand why, would the receiving equipment be considered outside the equipotential zone?

 

[Martin Dawes]

I was just assuming that the aerial will be mounted outside the equipotential zone.

I've not been asked to do anything like that before with regard to earthing aerials but I can definitely see the issue.

 

[MNR]

I was running in supplies for blocks of flats communal aerials and they did specify a 4mm2 clean earth to be run as well.

 

[Hawk81]

Perhaps it is to dissipate a static charge? I don't think it's a requirement in the regs but it's certainly not a bad idea.

Remember, if it's a PME system then it will need a seperate earth rod.

why? the separate earth rod for everything PME is not true!

 

[Martin Dawes]

why? the separate earth rod for everything PME is not true!

Where else could you bond it to? You can't take it to the PME?

 

[Hawk81]

Where else could you bond it to? You can't take it to the PME?

why can it not be taken to the PME?

 

[Martin Dawes]

why can it not be taken to the PME?

Because you would be taking the PME outside of the equipotential zone. You would need electricity board permission and in my experience they are reluctant to give you an answer.

 

[Hawk81]

Because you would be taking the PME outside of the equipotential zone. You would need electricity board permission and in my experience they are reluctant to give you an answer.

the airel is not going to introduce another earth potential to the installation. plus you do not need board permission to export a PME earth. they prefer it if you dont but it is simply up to yourself.

 

[Martin Dawes]

the airel is not going to introduce another earth potential to the installation. plus you do not need board permission to export a PME earth. they prefer it if you dont but it is simply up to yourself.

I was told something completely different by my NICEIC inspector. He pulled me on a garage/studio conversion that I installed a few years ago and said that I should have installed a seperate earth rod. He wasn't impressed either....

 

[Hawk81]

I was told something completely different by my NICEIC inspector. He pulled me on a garage/studio conversion that I installed a few years ago and said that I should have installed a seperate earth rod. He wasn't impressed either....

the NICIEC are not always right

 

[Martin Dawes]

This is true. And I could well be wrong. It seems to me that installing an earth rod would go a long way to covering yourself if a problem ever occurred though.

 

[Spudnik]

I think basically it is to stop any voltage appearing on the cables, or more to the point, the exposed parts of any equipment they are connected to.

Quote:



"In essence an aerial system cannot be left so that any hazardous voltage can be present on the outer conductor of any cable or accessible metalwork of any equipment. This means that we need to equipotentially bond all communal systems within blocks of flats, apartments, offices etc to the MET of the building. In order to do this a verified, continuous and robust connection needs to be provided from the distribution equipment to the building’s MET. Our regulations state that the minimum CSA of this connection should be 4mm2 copper.

In addition class II electronic equipment (televisions, DVD recorders, set top boxes, audio equipment – including AV amps, etc) is designed in such a way that a touch current of up to 0.5mA could be present on any exposed metalwork. Whilst as a single item this is not a problem the guaranteed safe let-go current for the population is 3.5mA. Hence joining 7 pieces of this type of equipment together (either via aerial or SCART leads etc), even in different rooms, could put a touch current of this amount on the coaxial cable. On new builds and when doing rewires it would therefore be useful to leave a verified earth cable next to the distribution point to take care of this possible hazard. This even applies in a single household."

Borrowed from here:

Downloads - Electricians - Aerial systems for a digital age