[JarodL]

I have always read that running your coax cable into a surge protector before plugging it into your cable box is a bad idea because it degrades signal strength and quality.


Is there any truth to this? I have two APC S10 Conditioner/UPS supplies arriving next week and I was wondering if I should plug my coax cables into them.


Also, any reason to use something like Blue Jeans Cables coax cables instead of the stuff the cable company gave me? Cable quality make a difference for coax?

 

[dragonfyr]

A reliable unit will specify the flat loss imposed by the circuit.


And with every connection there is what is called 'insertion loss' that quantifies the effect of a physical connections efficiency.


How much insertion loss is experienced, check the unit itself. This, alone with the signal to noise (S/N) ration will (should) be specified.


As far as will fancy coax somehow mitigate the upstream source typically consisting of a possible microwave link to a sub head-end, trunk line, feeder lines and cable drop, and assorted ground blocks, splitters and distribution runs inside the house?


I don't know of any interconnect of any kind that can restore something that has been lost. They are not program sources. The best they can do is reduce additional degradation.


The best coax is consists of a double foil double braid configuration, with the braid being dense. This makes the cable less flexible and less able to make extreme short bends. This configuration was originally developed by Belden for Viacom Cablevision in the early 1980's as they were working on the deployment of the first totally addressable two way systems and remains the best cable.


Is it necessary in a house for short runs? That depends on the degree of RF/EMI interference present. If there is much, then its worthwhile to utilize the maximum rejection possible. If not, then its overkill.


In any case, are you going to notice a dramatic difference. Most likely not. You may notice slightly less noise or spurious interference, but as far as the program material itself, there will be negligible difference in picture quality and flat loss for such a short run.


And if, after they install the system, you experience excessive noise, then get them out to troubleshoot the line. And if you insist on using your own gear, realize that they will not support this, and the onus will be on you to demonstrate that the problem is one of THEIR making and not yours. And realize, that the majority of problems encountered in such situation are due to the customer going to Home Depot or Lowes and using splitters, connectors, etc., that modify the distribution impedance via improper crimp tools used for fittings, as well as splitters and AB switches that not only exhibit loss, but generally do not exhibit the same S/N characteristics (typically a difference of 60 dB versus 90+ dB noise figures).


Thus, the most you can expect is to maintain the quality of the signal that enters the house.


And yes, it is worthwhile to protect devices from surges on BOTH the AC and tuner inputs.

 

[gregzoll]

Yes, it is a very bad idea, unless the surge is a part of a whole house system, and uses a Gas Discharge. Surge protectors are very good at causing problems with catv house systems.


Proper way, is make sure that the ground block where it enters the structure, is grounded to earth ground, and also use a gas discharge at that point to help further eliminate any problems. The reason for the gas discharge, is that it will blow before any surge from a lightening strike will enter the structure.

 

[dragonfyr]

Unfortunately grounding, whether a ground block earth ground or common bonded with the electrical service will not necessarily provide any protection from lightning or surges.


And whole house protection is not necessarily an option in apartments, etc.


And units such as those by APC, Leviton and others featuring local AC, coax and phone seldom cause problems. If one exists it is generally a result of the house wiring not being configured correctly and not the device itself. And such devices will not compensate such issues.


Unfortunately, none of the methods are foolproof. But if you are determined to use surge protection, fine. Just realize that it may be as much psychological as it is actually effective.


The easiest, but not necessarily most convenient, solution is to simply unplug ALL of the I/O in the event of a storm.


And you do not need fancy coaxial connections. In fact, unless you have the proper crimp tools you may very well create more problems and reflections than you will potentially fix. And it is generally easier to address local RF/EMI issues than to rely on a simple interconnect, as if sufficiently severe, the interference will find many additional sources of ingress into the system as well.

 

[walbert]

One thing to consider with this, is the bandwidth of the strip (I'm sure that isn't being said "right") - basically it's like the older splitters you might still find, that are only spec'd up to 900mhz or thereabouts, and will wreak havoc on DTV systems. Some strips do the same thing (you can have random dropouts or blocking as a result) - they can also serve as a source of ingress. I've seen this measured and demonstrated with suitable equipment, but do not have a link/citation for you.


If the cable system is properly installed, it'll have an earth ground at it's box (and if it's a sat system, that has to be grounded as well); tying it onto the AC earth may just open you up to grounding problems or introduce other issues (like ingress). I'd probably pass on such a connection.


I agree with most of what dragon said too. You're never gonna "win" against lightning; that's what insurance and repair-people are for (after the fact).

 

[Colm]



Quote:
Originally Posted by JarodL /forum/post/21790358


I have two APC S10 Conditioner/UPS supplies arriving next week and I was wondering if I should plug my coax cables into them.

Try it and see what happens. The tiny extra capacitance added by the MOV should not be of any consequence. If you can watch everything you want without degradation, you are good to go.


FWIW it is probably a good idea to run your coax through the S10. These things shunt surges to ground. This literally causes a surge on the ground. If all conductive paths to your gear run through the S10, it is not a problem. They have the same ground reference. If the coax doesn't run through the box, the ground voltage on it can differ from the ground voltage your gear is seeing and actually cause damage that would not have happened if you had no protection at all.

 

[Jetmeck]

Have had cable/sat installer/repair guys repeatedly tell me running their coax through my surge protector would cause problems. I was like ... really....

being doing it this way for years with no problems and oh btw is that coax grounded.......??? That last question ends the discussion.


Running your cable or sat through a surge protector will not cause any problems whatsoever unless the surge protector is blown then its doing whats its supposed to do.

 

[Colm]



Quote:
Originally Posted by Jetmeck /forum/post/21795841


...unless the surge protector is blown then its doing whats its supposed to do.

No, a surge protective device that fails is not doing its job. A properly sized device will last many, many years.

 

[dragonfyr]

This conversation has reached the level of absurdity considering that folks arguing against devices not rated to accommodate the required bandpass (called a mistake and hardly the fault of the device!) and those who do not recognize that a local MOV based protective device that has functioned properly in the past destructs and thus in not nearly as effective going forward...


And MOVs suffer fatigue after protracted periods of sub-threshold stress.

 

[Colm]

The only thing absurd about this thread is your response.


FWIW it is a common misconception, fostered by the folks that sell series type devices, that MOVs are sacrificial elements. They are not. If they fail, they aren't doing their job. Yes, MOVs can degrade over time, although I wouldn't call it fatigue. Grains can sinter, effectively reducing the voltage at which the device goes from high resistance to low resistance. That said, a properly sized device will last 10 years or more. If you don't believe that, go read what Eaton has to say about it. I removed a whole-house device some time ago that had been in service for more than 10 years. I have point-of-use devices that have been in service longer than that. It doesn't take much of a MOV to survive that long in a point-of-use device. The maximum expected surge at a point-of-use device that has 30' of wiring between it and the panel is only about 90J.

 

[dragonfyr]



Quote:
Originally Posted by Colm /forum/post/21796118


The only thing absurd about this thread is your response.

Read about it? OK, so at least we know from where you are coming...those marketing brochures sure are handy, aren't they?


We were integrally involved with Oak Communications as their TC-35 converter was one of the very first commercially available devices to utilize the then new GE MOVs back in 1981-2.


They do fatigue over time due to stress.


And in the presence of a serious surge exceeding their rated threshold - as believe it or not, some are rated for less than a direct lightning strike in order to be more effective against most real world surges of lesser but still damaging levels - they will often destruct.


But I am glad you have read something about them.

 

[Colm]



Quote:
Originally Posted by dragonfyr /forum/post/21796164


And in the presence of a serious surge exceeding their rated threshold - as believe it or not, some are rated for less than a direct lightning strike in order to be more effective against most real world surges of lesser but still damaging levels - they will often destruct.

Yes, any MOV will die if subjected to a surge that exceeds its specifications. But as I said, the maximum expected energy seen by a type 3 surge protective device (point-of-use located at least 30' from the panel), is about 90J. It ain't hard to build a device that will survive in that environment for a very long time.

 

[Jetmeck]



Quote:
Originally Posted by Colm /forum/post/21795846


No, a surge protective device that fails is not doing its job. A properly sized device will last many, many years.

Actually I wouldn't think I need to expalin this but here goes..........


A surge protector will protect devices plugged into them when a surge of electricity whether from your own electric company or lightning strike. It sacrifices itself to PROTECT your valuable equipment. Its that simple. Carry on.

 

[Colm]



Quote:
Originally Posted by Jetmeck /forum/post/21796471


A surge protector...sacrifices itself to PROTECT your valuable equipment.

Saying it twice doesn't make it true. You need to do some research.

 

[dragonfyr]



Quote:
Originally Posted by Colm /forum/post/21796606


You need to do some research.

You certainly do.


And while you are at it, research why they do not have an indefinite life span due to the result of fatigue due to accumulated stress.


While you have read about them, we designed with them - in concert with the GE development engineers. So while you are at it, you might want to drop a note to GE and inform them.

 

[Colm]



Quote:
Originally Posted by dragonfyr /forum/post/21796682


And while you are at it, research why they do not have an indefinite life span due to the result of fatigue due to accumulated stress.

Why would I do that. I have already done it. I said they can degrade (call it fatigue if you want). I described the process very generally. I never said they have an infinite life span. I said an appropriately sized device will last a long time, 10 years or more from my experience and according to Eaton (and other manufacturers that I did not mention). Look at the rating tables published by the MOV manufacturers (OOH! marketing literature!). They show the maximum surge a device is expected to survive once. They also show how many lower intensity surges the device is expected to survive. The less surge energy, the more surges it can survive. And all other things being equal larger diameter MOVs can withstand more of a given size surge. So take a type 3 device like OP has, installed 30' or more of wiring from the panel. Maximum surge energy expected is only 90J or so. A surge protective device with MOVs rated many times 90J can be expected survive many of the relatively infrequent 90J surges, and many more lesser surges, and last many years in the typical environment. They are not sacrificial devices. They are not intended to die protecting a device form a surge. They are intended to be used in a way that they can withstand many surges over a long operating life time. An air bag in a car is a sacrificial device. It operates once and is useless afterwards. Such is not true of a properly designed MOV-based surge protective device.


FWIW it seems to me that a lot of MOV failures that are attributed to surges are more likely due to sustained over voltage conditions, something MOVs don't deal with at all well.

 

[dragonfyr]

LOL!

This just goes in circles.


Look, you were the one who took exception to another who said essentially that an MOV can function in the process of self-destructing.


And indeed they can.


They can shunt a short term transient over-voltage condition to ground just as intended and in the process destruct due to the involved transient current just as the earlier fellow intimated.


And, as was also observed, after that they are not nearly as effective - and the owner of the surge protector may not have any indication that such destruction has occurred.


Sorry if this confounds you, but the rest of us have not had any problem understanding the very simply practical explanation of their basic function by others where they recommended them for local point source protection - to the limited degree of protection they offer.


But if you edit your posts a sufficient number of times, you may succeed in making your objection germane to the original issue.

 

[Colm]



Quote:
Originally Posted by dragonfyr /forum/post/21796797


Look, you were the one who took exception to another who said essentially that an MOV can function in the process of self-destructing.

No, that is not what I said. You keep trying to twist what I said.