Kitz Forum

Broadband Related => ADSL Issues => Topic started by: setecio on April 24, 2008, 07:15:10 PM

Title: Can you get electric shocks from phone wiring ?
Post by: setecio on April 24, 2008, 07:15:10 PM
I read that there can be 50v travelling down the telephone lines ?

Is there a danger of getting a nasty shock when doing some diy telephone wiring ?
or is it only a danger if someone happens to ring while you are touching the wires ?
Title: Re: Can you get electric shocks from phone wiring ?
Post by: jabns on April 24, 2008, 07:20:30 PM
Its not nice. I have had it before and it hurts.

Its not enough to kill you though but its defiantly not pleasant.

Just don't hold the two wires in your junction box at the same time(i can't believe i was so silly).

James
Title: Re: Can you get electric shocks from phone wiring ?
Post by: roseway on April 24, 2008, 07:26:47 PM
And don't strip the wires with your teeth. :)
Title: Re: Can you get electric shocks from phone wiring ?
Post by: tnp on April 24, 2008, 07:29:50 PM
And on no account go anywhere near it during a thunderstorm.

(speaking as someone who returned home to find most of the electronics in the house more or less destroyed, a thin smear of carbon where the telephone line used to be, holes burnt in carpets, sockets blown out of the wall..etc etc..: insurance insisted on a total rewire.)



Title: Re: Can you get electric shocks from phone wiring ?
Post by: setecio on April 24, 2008, 09:34:55 PM
OK, thanks for that advice.

Crikey tnp .... sure it wasn't a microwave bomb being tested nearby ?
Title: Re: Can you get electric shocks from phone wiring ?
Post by: oldfogy on April 24, 2008, 11:35:43 PM

1. Is there a danger of getting a nasty shock when doing some diy telephone wiring ?

2. or is it only a danger if someone happens to ring while you are touching the wires ?
1. There is no danger as such unless you suffer from a very weak heart condition.
("HOLD" your tongue across a good 9V battery and thats what it "possibly could" feel like)

2. Yes there is a constant voltage, and you may be more susceptible "if" someone rings.

Don't let it frighten you it's not that bad, honest, I have done plenty in my time and never had a bad experience yet.

And as a ex electrician I couldn't even use a "Neon Tester screwdriver" without getting a reasonably good tingle, so I should know. :flamer:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: guest on April 25, 2008, 08:21:50 AM
50Vdc at the amperage present on the phone line is nothing.

I've told kitz this one before but I used to work with a guy called Dave who was possibly the most talented analogue designer I have ever met. The man was a genius but as with many people like this he was also a bit mad. His method of testing whether things were live was basically to grab one wire in each hand and if it hurt then it was live. I've watched him loads of times "testing" 415V three phase supplies this way and that does hurt :lol:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: mr_chris on April 25, 2008, 08:54:47 AM
lol - is he still alive?!
Title: Re: Can you get electric shocks from phone wiring ?
Post by: setecio on April 25, 2008, 09:00:03 AM
Here is one of his kids

(http://i142.photobucket.com/albums/r107/setecio/kid-with-static-hair.jpg)
Title: Re: Can you get electric shocks from phone wiring ?
Post by: roseway on April 25, 2008, 09:01:54 AM
:lol:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: jabns on April 25, 2008, 01:40:14 PM
 :lol:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: oldfogy on April 25, 2008, 01:53:20 PM

Here is one of his kids

And a distant relative.   
(http://i92.photobucket.com/albums/l39/oldfogy/mona5.gif)
Title: Re: Can you get electric shocks from phone wiring ?
Post by: guest on April 25, 2008, 01:56:07 PM
:lol:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: tnp on April 25, 2008, 02:09:06 PM
IIRC is more like 75V DC on the phone line, which isn't such an issue..until someone phones you and you get about 70VAC of ring voltage..now that, as anyone who has had their mitts across a power amplifier when a drug crazed rock'n'roller hits a power chord, is nasty.  It wont kill you, but it surely wakes you up!

Title: Re: Can you get electric shocks from phone wiring ?
Post by: Astral on April 25, 2008, 02:09:18 PM
Brilliant. :lol:

Title: Re: Can you get electric shocks from phone wiring ?
Post by: Ezzer on April 25, 2008, 02:50:12 PM
On a normal phone line you get 50v dc at a low ampage, you can feel it, bit uncomfortable but thats all. if the line rings then thats 90v ac and you most definately feel it and it hurts!

ISDN runs at 95v, nowhere near leathal but gives an unexpected kick. DACS is the biggie at 140v. The biggest risk is when your hand comes back as an involitary action from the shock, Doing this on the frame in an exchange can result in cuts to the back of the hand as you catch the neigbouring fuses, known as frame rash.

HERES THE IMPORTANT BIT HENCE THE CAPITALS AND ANY ELECTRICIAN/ELECRTICAL ENGINEER WILL BACK ME UP ON THIS.

ALWAYS ASSUME THERE MAY BE MAINS/HIGH VOLTAGE ON ANY WIRING, INCLUDING TELEPHONY. I HAVE HAD QUITE A FEW JOBS WITH MAINS VOLTAGE ON THE LINE. TYPICALY ON THE INTERNAL WIRING. IT DOES HAPPEN

A BT ENGINEERS HAWK, 9083, BUTT PHONE ALL TEST FOR HIGH VOLTAGE FIRST FOR THIS REASON.

ALSO AS PREVIOUSLY STATED DO NOT TOUCH MAINS/TELEPHONY IN A THUNDERSTORM, SUCH SURGES DOWN THE LINE ARE COMMON. AND FOR SAFETYS SAKE I'LL REPEAT THAT, LIGHTNING SURGES DURING A STORM ARE COMMON! THATS THE ONE TIME BT ENGINEERS ARE NOT PERMITED TO TOUCH ANY OF THE NETWORK.
Title: Re: Can you get electric shocks from phone wiring ?
Post by: Astral on April 25, 2008, 03:05:32 PM
Quote
Doing this on the frame in an exchange can result in cuts to the back of the hand as you catch the neigbouring fuses, known as frame rash.

I haven't run a jumper for 35 years but the back of my hand started itching reading that. Funnily enough I was going to mention the "collateral damage" from getting a belt of ringing current.
Title: Re: Can you get electric shocks from phone wiring ?
Post by: oldfogy on April 25, 2008, 04:09:03 PM
Not wanting to digress from the original topic, but.

Back in the 60s BT used to charge the earth for installing extension phones, well we used to have the odd one or two going spare ( ££ ).
Any-way, one of our work colleagues had one of these spare phones to install himself over the weekend,
on Monday morning back at work he said it had "BLOWN-UP" :flamer:

He had connected it to a 13 amp plug and plugged it in.  :lol:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: setecio on April 25, 2008, 04:25:40 PM
Back in the 60s BT used to charge the earth for installing extension phones,

I've a feeling we're back in the 60s again.
Title: Re: Can you get electric shocks from phone wiring ?
Post by: Ezzer on April 25, 2008, 05:24:59 PM
Ther's and old story which I don;t know if it's true or aopocrphal.

 An engineer once was testing from an nte when the customer made a passing comment about a dog who goes nuts every time he hears a phone ring.

 Anyway the engineer could see the fault on his mole and summised it was in the underground lead-in to the house.

He then noticed that the dog in question was chained to a spike in the ground at a certain familiar distance (can you see where this is going ?)

He tried an experiment by getting to get the ring the line, but with apperatus plugged in so no ringing, but plenty of yelping and barking.

"Is that spike the dog's chained to new, perhaps put in the same time the fault occured ?"

sure enough they banged the spike through the phone cable so every time the phone rang the poor mutt got 90v ac in the neck.

Not so much Pavlovs dog but Pavlova dog :lol: :lol: :lol:
Title: Re: Can you get electric shocks from phone wiring ?
Post by: Astral on April 25, 2008, 05:32:06 PM
They certainly told me a version of that one on a training course in 1972. I think it was the earth on a shared service in that case IIRC.
Title: Re: Can you get electric shocks from phone wiring ?
Post by: guest on April 25, 2008, 06:17:01 PM
Must be me (or the influence of Dave :lol: ) but anything under a couple of hundred volts at a couple of amps isn't really much to be worried about.

I once got a 17kV shock off a bit of kit which we called "The Coffin". That hurt. That hurt lots :)
Title: Re: Can you get electric shocks from phone wiring ?
Post by: oldfogy on April 25, 2008, 06:23:12 PM
We had a party line once and I decide to move the phone. :angel:
Then our neighbour asked if by any chance we were having trouble with our phone.
As our neighbour started to receive our calls and we theirs. :lol:

When I realised it I managed to put it right. :police:

You have to remember in those days the equipment all belonged to BT and no one else was allowed to interfere with it (just for you young ones that is)
Title: Re: Can you get electric shocks from phone wiring ?
Post by: Floydoid on April 26, 2008, 10:37:41 AM
I remember those days OF - big phones with *dials which were hard wired into the sockets.

* it would seem strange to use a dial now we're all used to push buttons... I think the first push button phone I ever saw was a variant on the old trim phone at a friend's house ca.1977, and I thought "Wow!".