Satellite Dish Clarification

[mygoggie]

@GCE, thanks I appreciate the reply. Yes, I need a new one, but have been waiting and waiting for the 2019 version to be released.

[Dave A]

In my mind it is not about the cost because the owner is obviously responsible for that. It is a question of who is responsible for the work ? The antenna installer is not a qualified electrician, therefore he is not qualified to do the earthing work and he is thus forced to do an "illegal installation" of the antenna !! I am of the opinion that the installer should include the cost of calling out an electrician to make his installation legal in terms of SANS, in stead of leaving this task to the owner !!!

My old HD DSTV decoder failed and I had to replace it. I went with the new Explora 3a model via DSTV and took the satellite dish installation option as:

1. the new decoder needs a smart LNB, not a twin LNB
2. the new dish is larger than the old dish, so hopefully will result in less signal loss on bad weather days.

So the next day in comes the satellite dish installer who:

1. removes the existing satellite dish from its mounting bracket
2. installs the new satellite dish on the old mounting bracket
3. uses the existing co-axial cabling in place to connect the new LNB to the new decoder
4. removes the existing earthing in place on the satellite dish mounting bracket, clipping the earth wire a tantalising few millimeters short of the base of the bracket! (see image)

I get home that night, see the removed earthing, and called the installer to find out why he removed the earth.
He says it is no longer compulsory, so he removed it.
So I say - please supply me with a COC for the change.
He says he is not an electrician and can't supply me with a COC.
I point out the satellite dish installation is now in contravention of S 6.12.3.2 of SANS 10124-1 in that the mounting bracket is within arms reach of the ground (2051mm above the ground) and it is exposed to weather (as are most satellite dishes). He has rendered my electrical installation non-compliant.

He offered to come back and reinstate the connection.
As he was not going to be working under the general control of a registered person, I declined his offer.

What I really don't get is - Why didn't he just leave the earth alone?
Why remove it in the first place?

[Dave A]

BTW - My understanding of the current situation under edition 2 is that bonding may not be compulsory any more in terms of 6.13.2.3, but 6.12.3.2 means that almost all satellite dishes need to be earthed.

If I'm wrong, no doubt someone will correct me shortly...

[mygoggie]

BTW - My understanding of the current situation under edition 2 is that bonding may not be compulsory any more in terms of 6.13.2.3, but 6.12.3.2 means that almost all satellite dishes need to be earthed.

If I'm wrong, no doubt someone will correct me shortly...

Very, very interesting comment @DaveA. I would love to see what the 2017 SANS specs and our wise members have to say about this.

[GCE]

Hi

Under SANS 10142-1 - 6.12.3.2 I would put the earthing of a satellite dish as excluded under a number of points
Most dishes are out of arms reach
Could be regarded as structural steel work
Not touching a conductive surface ( was a thread previously over brickwork and conductive surfaces )

Backing that up I would use clause 6.13.2.3 as specifically mentioning satellite dishes - It does not have an earth terminal .

Further to SANS 10142-1 - The lightening protection guides recommend that you do not earth/ bond satellite dishes and aerials if they are below the safe space/ rolling sphere - If they are above then you need to use an isolated air-termination system to prevent lightening currents from entering the building over the coaxial cable.If you earth the dish or bracket without having an isolated air termination system then the bracket becomes the air termination rod and will create static or disturbance on the cable causing damage to equipment.It is all "hidden" in SANS 62305 - Have pasted a link to a useful document with regards to lightening protection - ( https://www.dehn-international.com/s...e-complete.pdf )

It is safer for the installation , house, to not earth or bond the aerial or satellite dish.
The minute you earth it it will also attract the stray static currents in the air which in turn will attract the possibility of a full lightening hit - That was my understanding on the topic.

I understood that the lightening protection discussion led to the removal of the requirement to bond/earth satellite dishes and aerials

Lightening protection is not my strong point but have attended lectures and studied the material to a point of basic understanding.

[Dave A]

Let's put up the first 3 clauses of 6.12.3.2 so that everyone is on the same page:

6.12.3.2 The following conductive parts do not need to be earthed:

a) short unexposed lengths of metallic wireway used to protect wiring as it
passes through a building element;

c)* exposed conductive parts of fixed electrical equipment that are

1) out of arm's reach from the floor (or walking) level,
2) out of arm's reach from a structure that is bonded to earth, and
3) not exposed to the weather or to the condensation, dripping, splashing or accumulation of water, and
4) not touching a conductive surface;

c) conductive parts that cannot be touched by the standard test finger;

(* posted as found. I assume this is a typo and should actually be b))

Under SANS 10142-1 - 6.12.3.2 I would put the earthing of a satellite dish as excluded under a number of points
Most dishes are out of arms reach
Could be regarded as structural steel work
Not touching a conductive surface ( was a thread previously over brickwork and conductive surfaces )

However, most are exposed to weather...

To my mind this entire discussion underlines the fundamental problem the industry faces with the standards -

The science, engineering and safety principles must inform the standards - no argument there. However, having been made prescriptive and with (potentially severe) penalties for non-compliance with the standard, any weakness in the wording of the standard resulting in the contractor failing to comply with the letter of the standard based on a safety argument becomes a significant risk to the contractor.

[Dave A]

On the lightning protection argument, I take it thinking has moved on since this position back in 2007.

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

[ACEsterhuizen]

Hi Alan, it seems my regs are out of date then:


SANS 10142-1:2017
Edition 2

6.13.2.3 Antennas
The conductive components of an antenna structure (including a satellite
dish) may be bonded to the installation earthing system by means of a
conductor of at least 2,5 mm2 copper or equivalent.

[Dave A]

Hi Alan, it seems my regs are out of date then:


SANS 10142-1:2017
Edition 2

6.13.2.3 Antennas
The conductive components of an antenna structure (including a satellite
dish) may be bonded to the installation earthing system by means of a
conductor of at least 2,5 mm2 copper or equivalent.

Nope. That is the current standard...

[AndyD]

.................I get home that night, see the removed earthing, and called the installer to find out why he removed the earth.
He says it is no longer compulsory, so he removed it.
So I say - please supply me with a COC for the change.
He says he is not an electrician and can't supply me with a COC.
I point out the satellite dish installation is now in contravention of S 6.12.3.2 of SANS 10124-1 in that the mounting bracket is within arms reach of the ground (2051mm above the ground) and it is exposed to weather (as are most satellite dishes). He has rendered my electrical installation non-compliant.

He offered to come back and reinstate the connection.
As he was not going to be working under the general control of a registered person, I declined his offer.

What I really don't get is - Why didn't he just leave the earth alone?
Why remove it in the first place?

I fully understand your frustration but I'll play devils advocate on this partly because I can also see why there might be confusion from the side of the dish installer. Relatively recently accessible earth bars were installed for the specific purpose of allowing other services to effectively connect to the MET without having to go into the DB. This basically gave other contractors such as plumbers, roofers, fence installers and DSTV installers an open invite to connect their own bonding. Yes, the absolute requirement of these earth bars in the regs has been removed since but bars that were installed are still out there and new bars may still be installed in existing or new installations.

If the bonding requirement for satelite dishes was for lightning protection then the specified 2.5mm sq CSA of the conductor specified is completely inadequate so I have difficulty accepting that as having been motivation for this reg. A 2.5mm sq conductor is only good for a CPC.

The regs on bonding over the last few years have been ambiguous, confused in their direction and poorly defined at best, I'm not surprised other trades are confused.

[Derlyn]

If the bonding requirement for satelite dishes was for lightning protection then the specified 2.5mm sq CSA of the conductor specified is completely inadequate so I have difficulty accepting that as having been motivation for this reg. A 2.5mm sq conductor is only good for a CPC.

I agree

In the event of a lightning strike that 2,5mm conductor will act like a fuse wire and disintegrate.


The regs also state that a metal roof must be earthed if the house has an overhead supply.
Whats the point of using 2,5mm wire for this when the overhead is either 10 or 16mm. Once again, should the overhead come into contact with the metal roof, that 2,5mm wire will disintegrate before the yorkshire fuse on the pole blows.

Derek