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Old 24-Jul-2012, 12:26 AM   #1
hdtvfan44
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Surge Protectors

I see a lot of surge protectors with a inbound connection for a coax cable and then an outbound connection. Do those actually work? And is it true those can create a signal loss?
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Old 24-Jul-2012, 1:25 AM   #2
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Theoretically, they add a level of protection. They should not cause a significant amount of loss.

Surge protectors incorporated into an outlet strip should not be the sole means of grounding. As the only grounding devise, they can be disconnected easily, leaving ungrounded coax throughout the premise.

It's best to ground the mast and coax before the antenna system enters the building. Adding a surge protector at the TV adds a bit more confidence that if a nearby lighting strike occurs, there are several paths to ground before the TV.
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Old 25-Jul-2012, 3:36 AM   #3
westom
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Originally Posted by hdtvfan44 View Post
I see a lot of surge protectors with a inbound connection for a coax cable and then an outbound connection. Do those actually work? And is it true those can create a signal loss?
Yes they cause signal loss. How much is determined by how much extra signal power is on your cable and the frequency. Losses in the Gigahertz range tend to be quite high.

Do you really think that little part inside a box will stop what three miles of sky could not? A protector adjacent to a TV must either absorb that energy or block it. So, which manufacturer spec number claims that protection? Good luck trying to find one.

Protection is about how a surge obtains earth. Once that surge is inside, then any appliance is a perfect victim for that connection. Once inside the house, then nothing stops a surge from hunting for earth destructively via appliances. As in nothing.

If a surge is earthed BEFORE entering the building, then it need not go hunting. But that connection must be low impedance. That means a ground wire from cable to single point earth ground (not just any ground) should be less than 10 feet. No sharp wire bends. No splices. Separated from other non-grounding wires. Why is that adjacent protector (and wall receptacle) not earthed? Many reasons are in sentences in this paragraph.

If a surge is earthed before entering the building, then nothing need become a victim. But this is critically important. No protector does protection. Either a protector connects low impedance to what does protection. Or it does nothing.

Protection is defined by what absorbs hundreds of thosuands of joules. Single point earth ground is far most important, easily compromised, and is the 'art' of protection.

"Art"? Some facts, that make or break that art, were already explained. Low impedance (ie 'less than 10 feet') is one example. And not just any earth ground. It must be the single point earth ground. Earthing - not any protector - not a receptacle safety ground - should have most of your attention.
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Old 25-Jul-2012, 5:58 PM   #4
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Excellent information on surges and surge protection is at:
http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf
- "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is a major organization of electrical and electronic engineers).
And also:
http://www.eeel.nist.gov/817/pubs/sp...%20happen!.pdf
- "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001

The IEEE surge guide is aimed at people with some technical background.

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Do you really think that little part inside a box will stop what three miles of sky could not? A protector adjacent to a TV must either absorb that energy or block it.
Protectors do not work by "stopping", "absorbing" or "blocking".

As the IEEE surge guide explains (starting page 30) they primarily work by limiting the voltage from each wire (power and signal) to the ground at the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment.

If using a plug-in protector all interconnected equipment needs to be connected to the same protector. External connections, like coax also must go through the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment.

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Originally Posted by westom View Post
So, which manufacturer spec number claims that protection? Good luck trying to find one.
Some manufacturers even have protected equipment warranties.

Both the IEEE and NIST surge guides say plug-in protectors are effective.

Quote:
Originally Posted by westom View Post
If a surge is earthed BEFORE entering the building
Service panel protectors are a real good idea.
But from the NIST guide:
"Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

Service panel suppressors do not by themselves prevent high voltages from developing between power and phone/cable/... wires. The NIST surge guide suggests most equipment damage is from high voltage between power and signal wires. An example of where a service panel protector would provide no protection is the IEEE surge guide example starting page 30.

But service panel protectors are very likely to protect anything connected only to power wires from a very near very strong lightning strike.

=====================================
The minimum antenna installation standards in the US should be the NEC. It requires a ground block where coax (cable, antenna, dish) enters the house. A ground wire connects the block to the power earthing system. The mast must also be connected to the earthing system. This is not protection from a direct lightning strike to an antenna or dish. For cable, in particular, it should be a short wire from the ground block to a common connection point on the earthing system.

Last edited by GroundUrMast; 26-Jul-2012 at 2:55 AM. Reason: Deleting off topic comments
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Old 25-Jul-2012, 9:26 PM   #5
OTAtime
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The mast must also be connected to the earthing system. This is not protection from a direct lightning strike to an antenna or dish.
So, is this protection for humans near mast/antenna in case of a potential voltage?

What is the appropriate wire size that should be used for this (ground from mast to earth)? For example, a case where antenna is approx 30' from earth ground rod in the attic.
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Old 25-Jul-2012, 11:31 PM   #6
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For example, a case where antenna is approx 30' from earth ground rod in the attic.
The mast would be earthed to connect electricity from the cloud harmlessly to earth. But your mast is inside the attic. There is no harmless path from a cloud to that mast.

A lightning rod, outside and above, will connect lightning harmlessly to earth. Don't earth the mast hoping lightning will blow through the roof. Earth a lightning rod so that lightning does not even strike the roof or mast.

Protection is always about the electrical path a surge (ie lightning) uses to connect to earth. If that path is a wire from a lightning rod to a better earth ground, then nothing is destroyed. What always defines protection? Not a lightning rod and not a protector. Protection is defined by the quality of its connection to earth.

If a best connection to earth is via the lightning rod, then the roof and attic mounted mast are best protected.

Last edited by GroundUrMast; 26-Jul-2012 at 2:57 AM. Reason: Deleting off-topic comments
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Old 26-Jul-2012, 1:26 AM   #7
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Quote:
Originally Posted by OTAtime View Post
So, is this protection for humans near mast/antenna in case of a potential voltage?

What is the appropriate wire size that should be used for this (ground from mast to earth)? For example, a case where antenna is approx 30' from earth ground rod in the attic.
The goal is to prevent an unsafe voltage difference between any part of the antenna system, including the coax, and any other exposed parts of the home electrical system and the connected appliances and fixtures. This is first and foremost to protect humans, if replaceable items such as TVs get protected, that's a bonus.

The NEC code (Article 810.21 (H)) calls for wire not smaller than #10 AWG copper. The code also allows for two other types of wire...

I spent a few extra cents per foot and used the larger diameter #8 AWG copper. My run is also between 20 and 30' from outdoor mast to the closest ground rod that's part of my electrical service ground system. The coax is run on the outside of the building, to a coax grounding block that's less than 2' from the same ground rod. The connections from the coax grounding block to the ground rod should also be not smaller than #10 AWG copper.
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Old 26-Jul-2012, 2:39 AM   #8
bud--
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The mast would be earthed to connect electricity from the cloud harmlessly to earth.
Hams who expect their antennas might be hit by lighting use far more elaborate protection. The mast ground wire handles static charges from wind and similar items.

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A lightning rod, outside and above, will connect lightning harmlessly to earth. Don't earth the mast hoping lightning will blow through the roof. Earth a lightning rod so that lightning does not even strike the roof or mast.
Lightning rod systems are engineered to protect. They would be very far down on my list of diy projects.

What does the NIST surge guide say about plug-in protectors?
They are "the easiest solution".
And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

And the IEEE? The guide has only 2 detailed examples of protection. Both use plug-in protectors. That is after detailed information on plug-in protectors.

Both the IEEE and NIST surge guides say plug-in protectors are effective. Read the sources. Excellent information on surge protection.

My only association with the surge protection industry is I am using some surge protectors.


Airplanes regularly get hit by lightning.
Are they crashing?
Do they drag an earthing chain?

Repeating:
The IEEE surge guide explains (starting page 30) plug-in protectors primarily work by limiting the voltage from each wire (power and signal) to the ground at the protector. The voltage between the wires going to the protected equipment is safe for the protected equipment.

Last edited by GroundUrMast; 26-Jul-2012 at 3:04 AM. Reason: Deleting off-topic comments
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