The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Safety at heights?
by gfretwell
01/19/17 07:16 PM
failed home inspection.
by gfretwell
01/19/17 07:03 PM
Webmaster > Admin
by Admin
01/19/17 05:49 PM
Old Bath Fan
by gfretwell
01/19/17 01:38 AM
Search Function
by Admin
01/18/17 11:13 PM
New in the Gallery:
Desk-mounted "power-board"
Top Posters (30 Days)
Admin 32
HotLine1 21
Ruben Rocha 16
gfretwell 15
Trumpy 13
Who's Online
2 registered (Admin, ComputerWizKid), 0 Guests and 191 Spiders online.
Key: Admin, Global Mod, Mod
Page 1 of 2 1 2 >
Topic Options
Rate This Topic
#31528 - 11/23/03 07:43 PM telephone wiring?
Edward Offline
Member

Registered: 12/14/02
Posts: 309
Loc: California
Does it matter if the tip and ring are reversed and why? How will the reversal cause a malefunction?

Edward
_________________________
Thanks
Edward

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#31529 - 11/23/03 08:12 PM Re: telephone wiring?
amp-man Offline
Member

Registered: 06/23/01
Posts: 144
Loc: Sacto, California US of A
With most modern equipment, a T-R reversal won't make any difference.

In fact, I've noticed the SBC installers are getting really sloppy recently with tip & ring conections at the drop.

Cliff

Top
#31530 - 11/23/03 08:33 PM Re: telephone wiring?
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Years ago before touchtone sets had "polarity guard" {in-set bridge rectifier} reversed polarity would kill tones generated by the keypad...but that was 20 years ago. [Some businesses would use per-pair reversing switches at the punchdown block to prevent after-hours outbound calls, while still being able to answer inbound calls.]

Top
#31531 - 11/23/03 09:00 PM Re: telephone wiring?
Big Jim Offline
Member

Registered: 07/18/03
Posts: 377
Loc: Denver, CO USA
A lot of older pay phones relied on "ring-ground-start" to bring up a dial tone after the money was inserted. As you might guess tip-ground-start didn't work and party lines relied on polarity to do selective ringing. In today's world, most equipment no longer cares. I still watch it as a matter of habit. right-red-ridge-ring.

Top
#31532 - 11/24/03 08:30 AM Re: telephone wiring?
BuggabooBren Offline
Member

Registered: 11/15/01
Posts: 336
Loc: NM
The 1A-2key equipment that we used to use in our large facility felt the effects of T&R reversal but I've not heard of any since the upgrades to electronic key and larger systems have gone in throughout the last decade.

[This message has been edited by BuggabooBren (edited 11-24-2003).]

Top
#31533 - 11/24/03 09:15 AM Re: telephone wiring?
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Just to add to what the others posted, "nowadays" it is not as important because of the electronics involved.

One of the symptoms I would hear (on some old phones)of a reversed T&R was that the ringer armature would move with the pulses generated when using a rotary phone. So, somebody would dial and you would hear the number as "dings." The good thing about those old phones is they are very immune to Radio Frequency Interference (RFI), and they were built like tanks--drop one and you might break the floor

I would think that keeping the correct polarity is important for troubleshooting. With the proper equipment, it is possible to tell if either the T or the R conductor has a problem with it, right down to the location of and type of problem. I would imagine if at some point the conductors were mixed up, it would create some confusion.

Then again, I've never done any actual telco-equipment work so this is speculation on my part

There is a great website that has loads of information on troubleshooting: http://www.mccartyinc.com/

P. S. To tell which is which, connecting a test set from ring to ground should draw dial-tone (with a hummmmmmm....) and from tip to ground no dial-tone.

Top
#31534 - 11/24/03 11:37 AM Re: telephone wiring?
BuggabooBren Offline
Member

Registered: 11/15/01
Posts: 336
Loc: NM
When I was on the Telephone Repair Cust.Svc. desk, we would have callers press their touch-tone pad keys and if we got 'click, click' we knew that it was reversed. Since it's been an eon ago I don't remember exactly how the phone calls were established, either us calling them on the reported line or them calling us but I think they'd report the phone line from another phone and we'd attempt a call to the errant phone which would ring fine and be usable, as Bjarney describes above.

Top
#31535 - 11/24/03 01:42 PM Re: telephone wiring?
amp-man Offline
Member

Registered: 06/23/01
Posts: 144
Loc: Sacto, California US of A
ThinkGood,

Having the calling set's bell make a little jingle when dialing out is called bell tap, or tinkle.

Shalom,

Cliff

Top
#31536 - 11/25/03 09:38 AM Re: telephone wiring?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
In British systems we always maintained correct tip and ring connections throughout.

Party line ringing has already been mentioned. Two-way party lines were once common in Britain, and as well as applying ringing to either tip or ring these also used a ground-start for outgoing calls, each subscriber having a button which he was instructed to press to get a dialtone. One party grounded the ring, the other the tip.

Many old step-by-step switches in both the U.S. and U.K. reversed polarity on the caller's line with supervision. Thus any of the older polarity-sensitive TouchTone pads would stop working once the called party answered.

Just think, had that situation continued, we could have escaped the "Press 1 for...., press 2 for....." frustration that we have to put up with nowadays!

Top
#31537 - 11/25/03 09:43 AM Re: telephone wiring?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Quote:
Since it's been an eon ago I don't remember exactly how the phone calls were established, either us calling them on the reported line or them calling us


The more enlightened subscribers may have called by pulsing out the number on the hook switch. It would be especially easy if 611 or 114 was in operation in the area.

Top
Page 1 of 2 1 2 >


ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals