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Thread: Satellite Dish Clarification

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    Silver Member Candy Bouwer's Avatar
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    Satellite Dish Clarification

    The question of new regulation for the earthing of Satellite Dishes has been raised this morning at a the Pinetown meeting of Dealer principles. I have been asked to investigate this further and require assistance.
    Please could someone clarify the issues surrounding this:
    a) the Dish being attached to the main earth or
    b) requiring a separate earth.
    Concerns stated at the meeting that there are confusion with this issue. As Electricians in general are climbing in on the band wagon and slapping every one with a +-R400.00 to earth them.
    The Bodies at the meeting generally agree that there should be earthing. However some schools of thought say that this should be separate to the main earth because of lightning conducted through the main that is obviously very dangerous.
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    Bronze Member Alan's Avatar
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    Hi Candy, i have not seen the latest up date on the regs, but as far as i am aware the Dishes, TV aerials etc have to be bonded to mains earth.
    As for running a seperate earth like we used to do, a earth spike into the ground i would agree and be happier with this........but then again we dont make the rules.
    As far as charges go, it would depend on the location of a suitable earth to where the dish is placed. I would not call R400.00 climbing on the band wagon. If the guy has driven to the job spent a couple of hours connecting the dish to the main earth, used 20 to 30m of copper wire which has had an 85% increase since January plus all the connectors, clips etc.........dont know if R400.00 is a rip off?
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    Silver Member Candy Bouwer's Avatar
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    Thanks Al ...but I need to report back on what the reg expects and not give my own understanding of the situation..could you find out what it is that has everyone asking for explanations about. Obviously the agents are feeling that the Electricians are just looking at this issue to make bucks so I need something official to give them.
    "NETWORKING" is a "CONTACT" sport!"
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    Bronze Member Alan's Avatar
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    Right....Reg 6.13.2.3 Antennas of SANS10142-1:2003 States
    "An Antenna (including a satellite dish) shall be bonded to the installation earthing system by means of a conductor of at least 2.5mm copper or equivalent."
    Remember the Ark was built by Amateurs and the Titanic was built by professionals.
    Business isn't about how to survive the storm, but how to dance in the rain.

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    Site Caretaker Dave A's Avatar
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    I got the following in a PM some time ago and asked the member to post it - which hasn't happened. But it's a great answer and really useful information. So on behalf of Indy and via Candy:

    I would like to reply to your request in forum, refer below,...

    wrt earthing the dish to the mains earth, this is good practice. The reason for this is that different "lighting paths" can cause potential differences during a strike.

    If there are 2 different paths to earth and there is a strike on the dish. The main earth would no longer be "earthed". It would be floating. A dangerous situation. Another danger is that the earth resistance is not measured. A rod is driven through the ground. The earth resistance is not measured and could be very high.

    Earthing the dish to the mains earth would eliminate this "floating" earth. Yes, the mains would have a high current during a strike, but the earth resistance is within spec.

    GOLDEN RULE : BOND EVERYTHING TO A COMMON EARTH
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    Hi!
    I am a little late to this thread - but as this is a new field of responsibility for me and answers seem to be forthcoming, I would like to try my luck:


    1) I fully agree - if the satellite dish is earthed, it should be earthed to common earth
    2) Q1: Having a bare earth running down from the dish to earth is probably more dangerous than not earthing it at all, so if earthed, should it should be done in a conduit or sheathed cable and not a bare cable?
    3) Q2: Is earthing regarded as electrical work requiring a qualified electrician, or can anyone do it?
    4) Q3: In the absence of an earth - e.g. a generator driven rural home - do you earth the dish, or not?
    5) Q4: If you earth the dish, do you earth the decoder, your TV and amplifier as well.
    6) Q5: ...and if so - who is responsible for doing it and who must carry the cost?

    I would really appreciate any input

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    Diamond Member AndyD's Avatar
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    Quote Originally Posted by Constant View Post
    Hi!
    I am a little late to this thread - but as this is a new field of responsibility for me and answers seem to be forthcoming, I would like to try my luck:


    1) I fully agree - if the satellite dish is earthed, it should be earthed to common earth
    2) Q1: Having a bare earth running down from the dish to earth is probably more dangerous than not earthing it at all, so if earthed, should it should be done in a conduit or sheathed cable and not a bare cable?
    Earth bonding can be an uninsulated braided strap in some circumstances so I don't think there's a requirement for bonding wiring to be insulated on a domestic premises....but I'd wait for confirmation.


    Quote Originally Posted by Constant View Post
    3) Q2: Is earthing regarded as electrical work requiring a qualified electrician, or can anyone do it?
    My personal opinion is yes. You'd need test equipment to identify what metallic objects are extraneous conductive and require bonding plus you'd need equipment to test the bonding impedance once installed.


    Quote Originally Posted by Constant View Post
    4) Q3: In the absence of an earth - e.g. a generator driven rural home - do you earth the dish, or not?
    Regardless of the source of the power, every domestic electrical installation requires an earth. If the sole power source is a generator then an earth rod would be required.


    Quote Originally Posted by Constant View Post
    5) Q4: If you earth the dish, do you earth the decoder, your TV and amplifier as well.
    I don't understand your question, I think you're getting confused between 'earthing' and 'bonding' which serve very different purposes.

    Quote Originally Posted by Constant View Post
    6) Q5: ...and if so - who is responsible for doing it and who must carry the cost?

    I would really appreciate any input
    The cost is for the homeowner's account usually.
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    Thanks a lot Andy!
    I really appreciate the feedback.
    You are right - I am confused between bonding and earthing. Could you help explain the difference to me please?
    (I assumed that as most TVs, amps and definitely the decoders only have 2-pin plugs nowadays, they aren't earthed and earthing the dish might entice a current through all of them if induced from the mains side - that's why I thought they might require special care as well)

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    Diamond Member AndyD's Avatar
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    Sorry about the delay, I've not had time to make a decent reply to this topic.

    Earthing

    In simple terms, earthing is an integral part of every electrical supply circuit. It's the conductor that is never fused or switched and it connects the chassis of every item or appliance to earth potential (0v or ground). The idea is that if there's ever an internal fault that causes the live or current carrying parts of the supply circuit to come into contact with the chassis then the earth will allow a fault current to flow safely to ground and hopefully one that's large enough for the circuit protection to trip and disconnect the circuit.

    The earth connection also prevents the appliance chassis developing a dangerous voltage under fault conditions with respect to ground. Anyone coming into contact with a faulty appliance is standing on the floor and can create a path through their body for current to flow which can cause injury if they touch it. The earth connection is designed to offer a lower resistance path for fault currents hence reducing the likelihood of injuries occurring.

    Finally the earth is also functional. It's normal for small currents to flow down the earth wire even when there is no fault as such. Many electronic devices such computer power supplies and lighting ballasts etc have built in surge arrestors. These surge arrestors allow any high voltage surges or spikes to be connected and sink directly to the earth therefore preventing damage to the equipment.

    So in short the earth is both a functional and protective part of an electrical circuit or installation which protects the user from coming into contact with dangerous voltages and causes rapid disconnection in the event of a fault.

    Some appliances do not require an earth connection because they're constructed in such a way that it's highly unlikely they can develope a fault that could ever give the user a shock. Often these items are double insulated or have a plastic chassis or case which is non-conductive so even if an internal fault occurs it can't result in a hazard to the user. These appliances usually have a special identifying symbol consisting of two squares, one inside the other and are known as class 2 insulated. These appliances could have a two pin plug because an earth is considered unnecessary in this case and TV decoders and laptops etc often fall into this category.



    Bonding

    Bonding is simply connecting metallic objects together with a low resistance wire or conductive strap. This ensures they can't develop a voltage with respect to each other.

    If objects are connected together and also a connection is made to earth then this is called earth bonding because all the objects connected together are also tied to zero volt earth or ground. Same applies to a single object that is connected to earth, this object is then held at earth potential therefore it's earth bonded. The earth bonded items can't assume any voltage other than zero with respect to earth whereas unearthed bonding will allow the items connected together to 'float' at any voltage applied to them although they will always remain a no voltage with respect to each other.

    Bonding is often misunderstood, we don't bond small objects that are unlikely to suffer a rise in voltage or potential, for example bonding is not required on most building elements such as metal shelving or door / window handles. If it's a metallic object that leaves the premises such as a water or gas pipe then it would require bonding. This is often referred to as the difference between objects that are 'extraneous conductive' or 'exposed conductive' and ones that are 'non conductive' in the electrical industry.

    The decision whether to bond or not is an important one and requires testing of the object in question and understanding of equipotential zones in order to decide which of the above categories an object falls into. Unnecessarily earth bonding can actually introduce a hazard of shock where there wasn't one previously. For example you won't get a shock if you are on an insulated floor surface whilst touching something live and you simultaneously touch a metal door handle on a wooden door but if the handle is earth bonded it them provides a low resistance earth path and a fault current will then flow and you'll get a shock. In this case if you add supplimentary bonding to the door handle you've turned a non-conductive part into a conductive part by connecting it to earth, this unnecessarily increases the risk of shock.

    Bonding is a fairly complex subject on its own and in the interest of keeping this explanation simple and understandable there's some factors and aspects I've glossed over. It's critical it's done correctly for the safety of the buildings occupants and not something a person without the relevant competence such as handyman or DIY homeowner should attempt.
    Last edited by AndyD; 13-Jan-14 at 06:45 PM. Reason: Spelling etc
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  10. Thank given for this post:

    Constant (14-Jan-14), Dave A (13-Jan-14), flaker (14-Jan-14), Leecatt (14-Jan-14)

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    i am aware the Dishes, TV aerials etc have to be bonded to mains earth.but what i would like to know , how come a dstv installer can compromise a installation and a COC on a Town house where the outside of the house belongs to the body corprote and where they are to make sure all electrical work is done according to SANS 1042 and a coc gets done on all work now the installer tells me they cant earth it , earthing regarded as electrical work requiring a qualified electrician so the owner knows nothing about it as they are accredeted installers and makes it the owners problem should they not give a coc on there work?Or at least inform the owner that his coc is compromised .if it is posebel to compromise the electrical installasion should they not by qualified to do the earthing or get some one to do it.and with a geyser it is the same the bodycoppred gets some one Plumer and they compromise the coc by removing or changing bonding on pipes but the owner must take the fleck,if some one can give me some feed back on this. thanks roelie

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