ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Top Posters(30 Days)
Potseal 11
Recent Posts
600 KW 120/208 3 Phase Y protection
by Yooperup. 07/21/17 09:27 AM
1913 American Electrician's Handbook
by gfretwell. 07/20/17 01:08 PM
Green House wiring
by ghost307. 07/20/17 09:10 AM
Permit Snafus...AHJs and Contractors Jump in
by HotLine1. 07/18/17 08:06 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
239,182 Are you busy
174,577 Re: Forum
167,015 Need opinion
Who's Online Now
1 registered members (gfretwell), 37 guests, and 11 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#78554 - 10/03/01 10:14 PM Phone line Protection  
sparky66wv  Offline
Member
Joined: Nov 2000
Posts: 2,236
West Virginia
Just a curious Q...

Driving down Rte 60 I noticed a few places that the phone lines were perpendicular and intersecting the power lines. With my "worst case scenario" mentality, I pondered what would happen if the 4160V line came down onto the phone line, and what dangers to the public would be possible...

What is the voltage rating of outdoor phone cable? (They're currently converting to fiber optic, but I'm pretty sure the older ones are still copper)

Assuming the phone cable doesn't have the dielectric strength to hold back 4160V, would the grounded phonelines have enough "continuity" to open an OCPD?

Just where would this energy go if unprotected?

Good argument for cordless phones if my suspiscions are true!


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

2017 / 2014 NEC & Related Books and Study Guides

#78555 - 10/03/01 11:21 PM Re: Phone line Protection  
NJwirenut  Offline
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Phone lines are heavily protected against overvoltage, for both utility line contact and lightning protection. The energy would end up going into the ground at the nearest telco "can" or junction box, through a gas tube type of surge arrester. Assuming a utility line contact, the thin telco wires would disappear in a flash of copper vapor in a few milliseconds.

Surge arresters are also installed where the telco wires enter buildings, usually at the "network interface", and are supposed to be bonded to the electrical service grounding system.

Not much is going to protect against a direct contact with distribution lines (or a lightning strike) immediately outside a residence, but in general, the long wire runs and small conductor sizes effectively limit the energy "let-through" by the time it gets into your home.


#78556 - 10/04/01 02:46 PM Re: Phone line Protection  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Just where would this energy go if unprotected?

can it go to telemarketers first???
[Linked Image]


#78557 - 10/04/01 05:47 PM Re: Phone line Protection  
Tom  Offline
Member
Joined: Jan 2001
Posts: 1,044
Shinnston, WV USA
Whatever you do, don't count on the Telco surge arrestors to protect anything except an old fashioned rotary dial telephone and maybe some of the old pushbutton touchtones. Your modem, ansering machine, fax machine, and computer can all go up in the proverbial puff of smoke if you do not install additional protection.

I had an answering machine back in the 80's that ate some lightning. Luckily, the manufacturer thought they had enough additional protection built in & they gave me a new one free just so I'd send them the dead one so they could do a post mortem. The jolt even blew a few of the covers off the machine.

If you're smart, you won't talk on anything except a cordless phone during an electrical storm.

Tom

[This message has been edited by Tom (edited 10-04-2001).]


Few things are harder to put up with than the annoyance of a good example.

#78558 - 10/04/01 08:06 PM Re: Phone line Protection  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
The exchange (central office) end of lines here are generally fitted with discharge-type surge arresters, except where the cables are all underground. Sometimes arresters are used at strategic points elsewhere.

Protection at residences is poor to non-existent these days. The current jack units have a simple spark gap, but wired across the line rather than to ground.


#78559 - 10/04/01 09:27 PM Re: Phone line Protection  
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,878
NY, USA
Sparky,

"can it go to telemarketers first???"

I'm with you!!! [Linked Image] [Linked Image] [Linked Image]

Bill


#78560 - 10/23/01 12:22 AM Re: Phone line Protection  
Tom Baker  Offline
Member
Joined: Oct 2001
Posts: 30
Bremerton WA
The best protection is from a TVSS that has common power - phone - and coax protection this way they are all at the same potential in a surge. There are some hard wire units like this and surge strips too. To do it right you need both, more is better in surge supression.



Member Spotlight
mxslick
mxslick
Atomic City, ID USA
Posts: 803
Joined: October 2004
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.020s Queries: 14 (0.004s) Memory: 0.7866 MB (Peak: 0.9363 MB) Zlib enabled. Server Time: 2017-07-21 18:40:01 UTC