Randsl Dude
join:2000-08-13
Canada
| reply to brassy
Re: Fairly powerful shock from touching green line
Let me guess, you were working in sock feet on the concrete floor in the basement...the perfect ground 
Try wearing shoes next time...  |
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LazMan
join:2003-03-26
Angus, ON
 ·TekSavvy Solutions..
| reply to sbrook
said by sbrook  :Yeah, hitting him with a megger is NOT a nice idea! You're right - but he didn't seem to understand why we didn't see the humour in the test-call thing, until after the megger thing.... |
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sbrook
Premium,Mod
join:2001-12-14
H0H 0H0
 ·Rogers Hi-Speed
Host:
Rogers
Bell Canada
| reply to joshb
Nothing worth noting. The reason for a 48V connection for conventional telephones is now largely historical ... The network could be run on significantly lower voltages were it not for all the equipment designed for 48V supervisory currents and 60V+ ringing current.
Amongst other reasons, carbon microphones needed a significant bias current to work properly and with their inherent resistance, voltages over about 40V were required for reliability. Ringers needed 60V plus to make the bells work. The relays and selectors (uniselectors, and 2 motion selectors) in early strowger exchanges worked best with about 48V operating voltages to combine reliability and speed etc. Also, party line selection which was done by grounding a circuit may result in higher resistance completing the circuit.
DSL doesn' add much at all by comparison. |
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joshb
Don't sweat the small stuff.
Premium
join:2006-03-04
Calgary, AB
clubs: | reply to LazMan
How much extra voltage does a DSL connection add too the line? |
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sbrook
Premium,Mod
join:2001-12-14
H0H 0H0 | reply to LazMan
Yeah, hitting him with a megger is NOT a nice idea! |
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LazMan
join:2003-03-26
Angus, ON
·TekSavvy Solutions..
| reply to sbrook
One tester I used to work with, thought it was funny as HELL to start making 'test calls' on cables we weren't finished with. Nothing like banging your hands off the back of wire-wrap blocks as ring-current runs through you... But he got his... One day, managed to get him out into the field on a 'complex issue' - while he had a hand-full of pair, buddy at the next cross-box fired up the megger...
The tester realized that maybe he wasn't so funny after all.
Laz |
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sbrook
Premium,Mod
join:2001-12-14
H0H 0H0
·Rogers Hi-Speed
Host:
Rogers
Bell Canada
| reply to LazMan
You want the belts you get from old strowger equipment ... even though you're only switching 48V to get the ring, because of all the inductors on the line, you get very high spikes on every ring pulse. We checked it with an scope and found up to 400V spikes on every cycle, measured by a true RMS meter, the result was closer to 55V ... but that kicked! |
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LazMan
join:2003-03-26
Angus, ON
·TekSavvy Solutions..
| reply to BTS Niagara
If either side of the pair is dead-shorted to ground, you'll get a BAD hum on the line...
As has been said, nominal voltage in North America is -48vdc. Ring current, on a standard 1FL is between 60-110vAC at 20Hz.
As for 'ground' on the one side - you'll be seeing 0v differential to ground; that's not the same thing as being grounded...
Anyways - it's possible, espically in this humid weather, to get a shock from the voltage on the line - although it's more of an annoyance then painful. The sweating we're all doing right now increases the skins conductance, and allows the lower voltage/current to pass thru the body. Ring current, is painful! 
Laz |
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reelq
@rogers.com | reply to BTS Niagara
Sometimes... |
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BTS Niagara
join:2006-06-22
St Catharines, ON | reply to sbrook
if you put an ohms meter on the ground side it will show a ground
ring shows voltage |
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sbrook
Premium,Mod
join:2001-12-14
H0H 0H0 | reply to BTS Niagara
There is no ground side ... red and green are both offset to ground under normal circumstances. Otherwise party lines and other requirements for ground offset signalling such as "message" would never have worked. |
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BTS Niagara
join:2006-06-22
St Catharines, ON
| reply to DKS
said by DKS :The phone was ringing. The green wire is the ring. Red is tip. Ring voltage is between 70 and 90 volts DC. Either that or your brain rebooted... RED is the ring on inside wire(quad)green is tip and normally the ground side but the polarity obviously got reversed somewhere. and he must have been grounded causing the shock(shock happens)no big deal, no reason to get scared of playing with phone wires |
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me13
@bell.ca | reply to rizzler
Most of the time the inside wire is not grounded. |
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rizzler
join:2004-07-07
canada | reply to sbrook
your line isn't probably grounded. |
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sbrook
Premium,Mod
join:2001-12-14
H0H 0H0 | reply to DKS
Yeah, except that the guy who wrote the original got it wrong too ... he had the frequency at 25Hz, which for MOST old bell phones was too fast for the clapper! |
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DKS
Damn Kidney Stones
Premium,ExMod 2002
join:2001-03-22
Owen Sound, ON
clubs: | reply to sbrook
You did the same search I did. |
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sbrook
Premium,Mod
join:2001-12-14
H0H 0H0
·Rogers Hi-Speed
Host:
Rogers
Bell Canada
1 edit | reply to DKS
said by DKS :Ring voltage is between 70 and 90 volts DC. I hope not or the clapper in an old bell would hit one of the gongs and stay there! Ring in N. Am. phones is nominally 88V AC 20Hz superimposed on the 48V supervisory standing voltage between Red and Green. (For the UK, that's 60-75V AC 25Hz)
OP ...
You can't have gotten a shock from touching the green wire alone. You had to be touching something else, AND you had to have fairly moist fingers to get a significant belt from the supervisory voltage only. Having worked on old strowger exchanges, the 48V supervisory voltage is enough to "bite" when shocked with dry hands, but not to kick. It takes ringing to do that! |
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me13
@bell.ca
| reply to joshb
The phone line has 48 volts on it when on hook, but if you touch one side and either you are a good path to ground or another part of your body is touching another wire, metal structure, waterpipe, etc you will get a small usually harmless jolt. I think most of the jolt is from the unexpectiveness of receiving the jolt. |
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joshb
Don't sweat the small stuff.
Premium
join:2006-03-04
Calgary, AB
clubs:
·TELUS
·TekSavvy Solutions..
·Shaw
 ·Primus Talkbroadband
 ·GoDaddy Hosting
| reply to brassy
said by brassy :Theres just no way the phone was ringing though. I had a cordless one (connected to another jack) and it didnt ring. Did it feel good? 
On a side note you probably have a bad ground on bell's side. Even with that kind of voltage going through your body you would have known after the fact if it had rang on yah. Well as long your had voice mail and the person left a message that is.
--
If things made sense in life there would be no challenge in life. |
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chrispi5
join:2004-07-11
Toronto, ON
| reply to brassy
said by brassy :Theres just no way the phone was ringing though. I had a cordless one (connected to another jack) and it didnt ring. You did not hear it cause you rang instead. |
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