# Two Phone Demarcs?



## oldtimer (Jun 10, 2010)

Big John said:


> So, I've been tasked with upgrading some of our obsolete phone equipment. I rarely do telephony and just know some very basic stuff.
> 
> The new demarcation point was installed in 1991 and looks like this:
> 
> ...


 I M O the old equipment was just left in place. It looks like two incoming lines, The ground wire looks to be #12 or # 10 solid. Maybe someone with more experience in telephone equipment can comment. I am very interested myself.


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## ttech (Jun 1, 2010)

They are old arrestors and can be removed. 

The previous installer was either
1. Lazy 
2. did not want to mess with the "inside wiring" and only disconnected/reconnected the phone company side.
3 Realized the inside wiring did not reach the new d marc and left it.


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## Big John (May 23, 2010)

Thanks for the replies. 


ttech said:


> They are old arrestors and can be removed....


 Then am I correct in my assumption that those little black plugs are some sort of arrester? How the heck do those things work? :confused1:

EDIT: Found 'em. Those things are a "five pin protection module" and they can apparently do all kindsa sophisticated protection.

-John


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## jw0445 (Oct 9, 2009)

Big John,

Your correct about the black modules. They are your protection. Can't tell if they are solid state or gas but I would bet they are gas protection. I would try to pull dialtone before dismantling your old demarc. Trace your jumper wire out. Looks like you have about 17 lines and a special circuit. You may still have some working lines in the old demarc. Do the jumpers go to a punch down block?


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## Big John (May 23, 2010)

jw0445 said:


> ...Looks like you have about 17 lines and a special circuit. You may still have some working lines in the old demarc. Do the jumpers go to a punch down block?


 Actually, most of the lines go to the old demarc. All those old arresters are still active. 

Almost all the jumpers run from the NID, to the old demarc, to some weird plant intercom system, and then to 66 blocks.

What I'm doing is deleting everything between the NID and the 66 blocks. The intercom system is obsolete and needs 120V to operate, which means if we lose station service we also lose our phones.

Just out of curiosity, you picked out one "special circuit" and I was wondering what made you think that? Because while doing this, I sure as heck did find a "special circuit": That blue-and-white pair going to the NID actually has 180 volts DC on it!  I think it's a connection to a remote-terminal for ISO's SCADA system.

-John


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## Big John (May 23, 2010)

*T1 Connection*

So, it turns out that the "special circuit" isn't part of the utility SCADA at all. It's actually part of a T1 connection.

I'm really interested to know how this thing works. Why on earth would it be sending 180VDC back into the NID? The T1 comes out of some sort of networking box which has its own power supply. There is no fiber connection feeding the networking box, instead it looks like it's making use of several twisted pairs, meaning one or more phone lines.

Anyone have any information on what the heck I might be looking at here? Thanks.

-John


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## jw0445 (Oct 9, 2009)

Big John said:


> So, it turns out that the "special circuit" isn't part of the utility SCADA at all. It's actually part of a T1 connection.
> 
> I'm really interested to know how this thing works. Why on earth would it be sending 180VDC back into the NID? The T1 comes out of some sort of networking box which has its own power supply. There is no fiber connection feeding the networking box, instead it looks like it's making use of several twisted pairs, meaning one or more phone lines.
> 
> ...


John,

Back from vacation. A T 1 takes two pairs to work, a transmit pair and a receive pair. That is a normal voltage. If it is a scada circuit and your working a power plant it could cause a automatic shutdown if you work on it without taking it off line. I would look over your phone bill to see what your paying for and call the telephone company to see what that circuit is about. Probably running data on it but you can also break it out into phone lines.


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## MDShunk (Jan 7, 2007)

Big John said:


> Thanks for the replies.
> Then am I correct in my assumption that those little black plugs are some sort of arrester? How the heck do those things work? :confused1:
> 
> EDIT: Found 'em. Those things are a "five pin protection module" and they can apparently do all kindsa sophisticated protection.
> ...


Yeah, that whole assembly with the black arrestors is called a "Cook Block".


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## jw0445 (Oct 9, 2009)

Cook is actually a brand. The one pictured is not a Cook.


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## MDShunk (Jan 7, 2007)

jw0445 said:


> Cook is actually a brand. The one pictured is not a Cook.


Yeah, no chit, but the term "cook block" has been used to refer to that piece of equipment for a very long time. People would still call their Ricoh copier a Xerox machine and their Puffs tissues a Kleenex.


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## 76nemo (Aug 13, 2008)

MDShunk said:


> Yeah, no chit, but the term "cook block" has been used to refer to that piece of equipment for a very long time. People would still call their Ricoh copier a Xerox machine and their Puffs tissues a Kleenex.


 

hehehehahaha, good "chit".:laughing::thumbup::laughing: Good chuckle. COL:thumbup:


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