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Standard User smiffy12
(experienced) Tue 16-Feb-16 10:59:39
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Phone Line Surge Protection


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Hello, I live in an area with long overhead phone lines which are susceptible (spelling?) to surges when lightning storms are nearby. I've lost a lot of routers over the years (even using little Belkin surge cubes and surge protected extension leads which have RJ11 built in). Recently, the surge down the phone line was so strong that the computer and my NAS were blown too - expensive ouch!

I wondered, does anybody know of a decent telephone line surge protector that wouldn't have too much effect on line sync speed (or should I say line attenuation?) and that works properly. I can't help but think there must be such a thing, but I cannot seem to find it.

Thank you for any help
Standard User westom
(newbie) Wed 17-Feb-16 17:09:09
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Re: Phone Line Surge Protection


[re: smiffy12] [link to this post]
 
In reply to a post by smiffy12:
I wondered, does anybody know of a decent telephone line surge protector that wouldn't have too much effect on line sync speed (or should I say line attenuation?) and that works properly.

A phone line is required to already have that protection. But to understand, one must first learn how and why surges do damage.

Lightning (as demonstrated by Franklin in 1752) is hunting for earth ground. If lightning is earthed BEFORE entering a building, then it is not inside doing your damage. If your telco (installed for free) protector is properly earthed, then that is not the incoming path. IOW that protector does what Franklin did to protect church steeples. A surge that connects to earth on a better (more conductive) path does not pass destructively through church steeples or your NAS.

The most common source of destructive surges is AC mains (wires that are highest on poles). A surge is incoming to all appliances. But it is electricity. That means both an incoming and another outgoing path must exist. A best path to earth was via the computer and NAS (because your phone line already has best protection). Incoming on AC mains. Outgoing on phone line. Damage is often on the outgoing path.

Protection means every wire inside every incoming cable connects low impedance (ie less than 10 feet) to single point earth ground. That electrode used by your telco installed protector and AC electric must be same, must be the best earth ground, and must connected low impedance (ie wire cannot have any sharp bends).

TV cable can connect hardwired to this electrode - for best surge protection. Telephone cannot. So an NID connects every phone line to earth via a protector. Protector only does what a hardwire does better. That is what effective protectors do. Make a connection (just like a hardwire) low impedance (ie less than 10 feet) to single point earth ground.

Do all incoming AC electric wires make a low impedance connection to earth? Telephone, satellite dish, and cable TV are required to have protection. AC electric does not IF you do not install it.

Remember, a protector does not do protection. A protector connects to what does protection. Protection is the item that harmlessly absorbs hundreds of thousands of joules.

You (should) already have effective and proven protection on phone lines. If lightning is all but invited inside (due to no 'whole house' protection), then it will hunt for earth ground destructively. A best path to earth is via any appliance connected to phone or cable lines - due to protection already on those lines.

Edited by westom (Wed 17-Feb-16 17:11:12)

Standard User broadband66
(fountain of knowledge) Wed 17-Feb-16 17:25:34
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Re: Phone Line Surge Protection


[re: westom] [link to this post]
 
What are you actually trying to explain?

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Standard User smiffy12
(experienced) Sat 20-Feb-16 08:34:15
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Re: Phone Line Surge Protection


[re: westom] [link to this post]
 
Hello Westom and thank you very much indeed for your kind reply. I in no way profess expertise nor anything remotely close to it in terms of electrics and electronics, although I feel I should confess to originally having studied Mechanical Engineering and as a direct consequence, a bit of electrical engineering too. A precursor for this study was a good grade at higher physics which was satisfactorily achieved smile

As I say, I do not profess expertise in any way but am somewhat familiar with the properties and wants of electrical current and how it likes to flow and surge, etc. but I'm grateful for your reply smile

I have no idea if telephone exchanges have surge protection the phone lines, but if you tell me they do, then I'm happy to accept that and all that you saysmile If I pick you up correctly, you say that the phone line isn't the culprit as I'd said in my original post here, but that you say the issue is with the electrical mains side of things.

Our poles locally are not multi purpose. We have poles with mains electricity (and transformers at each 'take off' point). We also have separate poles which carry the copper phone lines for quite a distance.

This means that there is no hierarchy of cables on the poles here so if a pole is struck, that is the cable that pole carries will take the brunt (or surge down the wire assuming most of the belt shot to earth). Let's assume the lightning strike was on the overhead lines between the exchange and the affected premises (there were lots of affected premises btw). The telephone exchange surge protector works at the exchange. As it happens, this is a fairly small rural exchange and one of the line cards in the exchange and some other equipment was also blown to smithereens, it took a good month for things to be repaired in there! Let's next be sure in the knowledge that there was NO surge protection on the telephone line at the end users address. The strike hit the line (or a pole), the surge went in both directions along that line - to the exchange and did whatever damage it did there and in going down the line in opposite direction towards the end user premises where it did serious damage there too.

I kid you not, the small, white, rectangular box on the window sill that changes the external BT cable to internal type blew up and became a smouldering lump of blackened plastic with shards of it exploding across the room. In a split second after that the surge then destroyed NTE5, then carried on to the router - again it exploded and what was once a nice white router is now a blackened lump of blown up and melted plastic. As the network was wired it also passed on down the RJ45 side of the router breaking the switch, network connection in the NAS and the OB networking of a computer.

The problem is very much that a heavy lightning surge came down the phone line and did this damage and I cannot believe this is a one off which makes me think there must be an option for surge protection on phone lines at end user premises.

Pease can I ask again if anybody has any knowledge of a decent surge protector for RJ11 connections, or just phone lines in general? I'm quite happy if it needs a separate cable taken to the earth mains to take the surge away to earth, easy to wire a plug to do that but I just can't find anything? I doubt that much protection would be afforded on this given the power of the blast that nit, but anything would be better than nothing smile I truly would be grateful for any help. Thank you.
Standard User broadband66
(fountain of knowledge) Sat 20-Feb-16 11:29:17
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Re: Phone Line Surge Protection


[re: smiffy12] [link to this post]
 
Did you try Google?

Amazon have Phone surge protectors but don't know if they are any good.

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Standard User westom
(newbie) Sat 20-Feb-16 16:40:34
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Re: Phone Line Surge Protection


[re: smiffy12] [link to this post]
 
In reply to a post by smiffy12:
I kid you not, the small, white, rectangular box on the window sill that changes the external BT cable to internal type blew up and became a smouldering lump of blackened plastic with shards of it exploding across the room.

Lightning typically does not do damage as you observed. That typically occurs due to something called a follow-through current. Where lightning damage creates an electrical connection to something with much larger power. What follows a lightning pulse is that more powerful current called a follow-through current.

Examples of telephone protectors: this one in Australia demonstrates what protectors typically look like throughout the world and how to install it:
https://www.telstra.com.au/content/dam/tcom/personal...

Numerous devices from Bourns:
http://bourns.com/data/global/pdfs/bourns_osp_produc...

Keison offers products.
http://www.keison.co.uk/furse/furse11.htm
Another and similar type of protector:
http://www.novaris.com.au/uploads/1/Telephone-2013.pdf


Unfortunately some Keison installation pictures show a compromised installation. A protector's earth gound is too far away from electrodes as to make surge damage easier. Protectors must not be adjacent to electronics since a low impedance (ie less than 3 meters) connection is essential. Increased separation between protector and appliance (that increased impedance) also increases protection.

In every case, a protector has (what is often green) a dedicated wire that must make a low impedance (ie less than 3 meter) connection to the earth ground also used by AC electric and any other incoming wire. That means BT's phone wire must drop down near to earth BEFORE entering. So that a protector can make a low impedance connection.

No advanced physics is needed to implement these simple rules. Those basic electrical concepts explain why these rules exist. Every wire in every incoming cable must connect low impedance (wire without any sharp bends) to single point earth ground. That connection is made directly by hardwire for TV cable and satellite dish. And made by a protector for telephone and AC electric. If any incoming wire does not make that earth ground connection, then protection may be compromised.

Phone line is much rarely struck. But then many reasons (including follow through currents and other 'accidents') are why telco lines have always had protectors in every telephone exchange.

BT once installed them in Master Sockets. But since surges are so less often in the UK (compared to the rest of the world), then BT stopped installing it on many subscriber interfaces.
Standard User BatBoy
(sensei) Sat 20-Feb-16 17:04:04
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Re: Phone Line Surge Protection


[re: westom] [link to this post]
 
In reply to a post by westom:
Lightning typically does not do damage as you observed. That typically occurs due to something called a follow-through current. Where lightning damage creates an electrical connection to something with much larger power. What follows a lightning pulse is that more powerful current called a follow-through current.
Something with much larger power than a lightning strike? Nah.
Standard User broadband66
(fountain of knowledge) Sun 21-Feb-16 10:53:57
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Re: Phone Line Surge Protection


[re: westom] [link to this post]
 
Too much science!

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Standard User BatBoy
(sensei) Sun 21-Feb-16 11:12:56
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Re: Phone Line Surge Protection


[re: broadband66] [link to this post]
 
He's basically taken the method for protecting electricity generation equipment from lightning and stated that is what's required for phone line protection. It's nonsense.
Standard User Brunel
(experienced) Sun 21-Feb-16 12:32:19
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Re: Phone Line Surge Protection


[re: smiffy12] [link to this post]
 
If the 'phone line receives a direct hit from a lightening strike, nothing will protect it and anything connected.

The high voltage will destroy everything in its path on its way to reach Earth.
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