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Coax Protection: A Myth or a "Maybe?"

APC UPS for Home and Office Forum

Schneider Electric support forum for our APC offers including Home Office UPS, Surge Protectors, UTS, software and services and associated products designed to share knowledge, installation, and configuration.

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joypebble_apc
Crewman
Crewman
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Coax Protection: A Myth or a "Maybe?"

This was originally posted on APC forums on 8/11/2009


I live in Lightning Central in the Hudson Valley (Dr. Frankenstein has rented a castle nearby) and I am replacing cable modems and associated network and audio hardware from surges traveling through the Comcast coax cable wire that goes directly to the modem. (The electric power is contained by the surge side of my Back-Ups BR800 .) The coax bypasses everything and zaps the network via the modem.

If I try to trap surges traveling through the cable coax wire (assuming that I’m properly grounded) I have these questions:

1) Will surge protectors degrade the cable signal enough to slow service or otherwise interfere with customer/Comcast interaction?

2) When most stand-alone surge protectors, after trapping a surge, they discontinue continuity to the modem. No signal until I manually reset the device. Is there a device that will not “break” the circuit on a spike, but still deliver a signal after the spoke has been trapped of shunted?

3) Sales suggested a BR1500-LCD UPS, which has coax in and out. When this unit protects against surges in the coax, what happens? Does that circuit reset automatically? Does the surge protection of this unit degrade the coax signal to the modem?

Many thanks for any thoughts.


---JP

Message was edited by: joypebble

Message was edited by: joypebble


Accepted Solutions
BillP
Administrator Administrator
Administrator
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369

Re: Coax Protection: A Myth or a "Maybe?"

This reply was originally posted by Jonathan on APC forums on 8/17/2009


You are very much welcome JP, and we're glad to hear the ComCast assisted you with the problem. Please do not hesitate to contact us if you'll have any problem using our products.

See Answer In Context

5 Replies 5
Techie_apc
Admiral
Admiral
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369

Re: Coax Protection: A Myth or a "Maybe?"

This was originally posted on APC forums on 8/11/2009


JP,

1) Will surge protectors degrade the cable signal enough to slow service or otherwise interfere with customer/Comcast interaction?

APC coax surge protection has an insertion loss of 2.3dB. If for example, the incoming signal was 2dB, when the surge protection device is installed the signal received would be 0dB. Therefore, this would have an inadequate signal when surge protection is added to the circuit if the incoming signal is 2dB. If the signal strength is high, then you will not have an issue with the Coaxial cable Surge protector.
Please view the below K-base document for more information.
[http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=912]

2) When most stand-alone surge protectors, after trapping a surge, they discontinue continuity to the modem. No signal until I manually reset the device. Is there a device that will not “break” the circuit on a spike, but still deliver a signal after the spoke has been trapped of shunted? 3) Sales suggested a BR1500-LCD UPS, which has coax in and out. When this unit protects against surges in the coax, what happens? Does that circuit reset automatically? Does the surge protection of this unit degrade the coax signal to the modem?

APC Surge protector redirects the excess voltage to ground if it is grounded properly when the Surges pass through the Data lines or Power lines. I have not seen a case with APC surge protectors that after trapping a surge, they discontinue continuity to the modem. However, If the Surge protector were to be overwhelmed by a surge transient the circuit within the SurgeArrest will “OPEN” sacrificing itself to save your computer. Therefore, not allowing any further surges to pass through to the protected equipment.

Secondly, APC believes in "let through voltage" rating. It is the BEST measure of performance. Accepted by UL as a standard test for surge protection. Let through voltage is a measure of the voltage that surge protector passes through and allows to reach the connect equipment. Products are tested using a 6,000v spike. Residual voltage that passes through the protector is measured and assigned as the “let through rating”. Please view the below K-base document for more information.
[http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=65]

BillP
Administrator Administrator
Administrator
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369

Re: Coax Protection: A Myth or a "Maybe?"

This reply was originally posted by Jonathan on APC forums on 8/11/2009


JP,

Aside from what Techie had said, if you already have a UPS or Surge Protector and wanted to have a bullet-proof protection when it comes to surge you may want to try or know more about our APC ProtectNets --> [http://www.apc.com/products/family/index.cfm?id=145]

rau_apc
Commander
Commander
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0
369

Re: Coax Protection: A Myth or a "Maybe?"

This was originally posted on APC forums on 8/17/2009


You should protect all incoming metalic lines, telephone, coax, power... And also grounding practices are very important, not only the protectors to be used.

It is recomended that all grounded wires be bonded at the point the wires enters any construction or at least the closest place where the wires come from the outside. If the coax ground is not bonded to the orther ground rods, a potential diference can rise on the separate ground rod(s) and high currents can now flow from one ground to the other through your electronics since these lines are "bonded" together inside the equipments by filter capacitors and also since the neutral wire (which is a grounded wire) runs very closely to the safety ground inside power suplies, surges between these lines can cause the electricity to arc inside the PSU and you can imagine the consequences of this.

Whole house surge protectors, for all metalic conductors coming in your house, is a very good choice as well. There are protectors (SPDs) of many types and for all applications. Bonding all grounding rods and grounded conductors at the right spot, is also mandatory!

For areas that are very prone to lightning strikes, whole house surge protectors is a must have as well as plug in protectors like surge protectors, UPSes and the like.

I recommend you reading this Guide from IEEE:

http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.pdf

joypebble_apc
Crewman
Crewman
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369

Re: Coax Protection: A Myth or a "Maybe?"

This was originally posted on APC forums on 8/17/2009


Many thanks for all the good ideas. Comcast came to the residence and shortened the ground for their cable by about 12 feet. The tech said that the longer the ground lead, the more chance for a poor ground.

Note: The only reason (in my opinion) why Comcast came so quickly and worked on this problem as a supplier issue rather than the usual, "Well' as a homeowner, you meed to ground your house. It's not OUR problem" as was the usual type of cop-out in the past, was that Verizon arrived on the road to offer the first real competition for Comcast in this area...ever.

God bless competition!

---JP

BillP
Administrator Administrator
Administrator
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370

Re: Coax Protection: A Myth or a "Maybe?"

This reply was originally posted by Jonathan on APC forums on 8/17/2009


You are very much welcome JP, and we're glad to hear the ComCast assisted you with the problem. Please do not hesitate to contact us if you'll have any problem using our products.