old looking earth spikes?

[sm1thson]

Ive often noticed old looking earth spikes outside peoples houses, generaly with a thin multicore none insulated cable thats generaly broken.

-are these old mains earthing? because they clearly dont look upto the job (either now or when they were put there due to the size of the cable)

the only other thing i can think of is that its telephone related!?! -but Ive never seen anything like that on any phone line Ive looked at in detail (when extending etc)

 

[Nige F]

They could be the earth wires from the Very early Rediffusion "cat`s whisker" wireless recievers .......they used to be rented to people for a few pennies a week .......they then went on to renting TV`s

 

[JohnD]

I had one of those earths on a 1924-built house I used to have... do you remember, Nige, if that was about when you used them? It was a bit of stranded (green!) copper wire (probably about 2.5mm sq equiv) going into the ground near the front door.

 

[Taylortwocities]

You may find they are part of the old telephone system. In the old days (1950/60ish) there were party lines (aka shared service) whereby two subsribers shared one telephone line. You got dial tone (and were billed) by putting an earth on the 'A' leg of the telephone pair and the other party got dial tone by putting an earth on the 'B' leg.

The phones had a push button on the top that you pressed to get dialling. The earth usually came from an earth rod as you describe.

This was a really crap system. Benefit for GPO was they only needed one pair of wires for 2 customers.

Downside for customers - you could listen to the other party's calls,

Benefit for those 'in the know': you could get your calls charged to the other party by swapping over the earth call onto the other leg of the telephone pair.


TTC

 

[plugwash]

iirc the system of party lines replaced first with WB9000 (a horrible analog system for running two lines accross one pair) and then dacs (a good quality digital system for running two lines over one pair that unfortunately connected to the exchange equipment over analog lines causing problems for modems)

 

[securespark]

But these GPO earths were not rodded, they came off a water pipe.

 

[Pensdown]

You may find they are part of the old telephone system. In the old days (1950/60ish) there were party lines TTC

Forget the old days, believe it or not there are still houses in rural locations that still have party lines. After a long fight with BT my brother finally got his own line in 2001 and he lives just outside of Tenterden

 

[Taylortwocities]

Blimey, have you got phones in kent now?

 

[sm1thson]

It was a bit of stranded (green!) copper wire (probably about 2.5mm sq equiv) going into the ground near the front door.

- thats the one!

They could be the earth wires from the Very early Rediffusion "cat`s whisker" wireless recievers .......they used to be rented to people for a few pennies a week .......they then went on to renting TV`s

-sounds likely, my last house (rented) had such a rod and had a rediffusion boxx thingy on the windowsill

You may find they are part of the old telephone system. In the old days (1950/60ish) there were party lines (aka shared service) whereby two subsribers shared one telephone line. You got dial tone (and were billed) by putting an earth on the 'A' leg of the telephone pair and the other party got dial tone by putting an earth on the 'B' leg.

-another possibility, interesting aswell, Im too young for all of that, lol.

so how do you tell if it is a mains earth? -i presume nowadays it will have a tag on it and a big fat sleaved cable, but if its an old one?

 

[plugwash]

ultimately if you find an earth rod that looks like a dodgy peice of **** you should check out the mains earthing, if the mains is adequately earthed by other means then you can ignore or remove the old rod. If not then you need to fix the mains earthing to modern standards.

 

[securespark]

ultimately if you find an earth rod that looks like a dodgy peice of s**t you should check out the mains earthing, if the mains is adequately earthed by other means then you can ignore or remove the old rod. If not then you need to fix the mains earthing to modern standards.

I should point out that a "good" EFL reading does not necessarily mean your installation is safe.

I have seen a TT install where the loop reading was sub 1 Ohm.

But remove the bonding to gas & water pipes, and it shoots up to 258...

 

[ebee]

Telephones?
What`s wrong with two "Marvel" tins and a piece of string?

 

[HDRW]

But these GPO earths were not rodded, they came off a water pipe.

Not necessarily - mine has a rod beside the front door, below the point of entry of the phone cable - the water pipe is at the other end of the house.

It's disconnected now, but there used to be a single strand bare copper wire clamped to it, running to the "GPO" terminal box inside the house. When he disconnected it the BT engineer said that it was a good quality Earth and that I could use it as such for an amateur radio antenna system - I've never tried to measure it to find out if it is a decent Earth or not.

Cheers,

Howard

 

[Chris.J]

Re BT earth rods : --
I thought these were always fitted in pre master socket days, and formed the earth path for whatever lightening protection was fitted.
There is a terminal (pin 4) designated for "earth" in the modern Master socket, but these seem to be rarely connected.
Some Master sockets used to have two gas discharge "suppressors" (one from each leg to this earth terminal), but thesedays they invariably seem to have just one across the line.
So, if you are overhead fed, and get a strike, IMHO both legs are likley to "go high". What does a single suppressor across the line do, not a lot I suspect. So how does the current get to ground.....through your Modem.
Good for Modem makers I suppose.
I always unplug the line to mine, and the mains plug for the whole of my Computer/Modem PSU etc whenever storms are about.
Any ex-BT guys out there like to comment?

 

[plugwash]

a suppressor between the two lines will protect anything that is ONLY connected to the lines.

modems are supposed to have pretty high degrees of isolation, not enough to withstand a direct strike (but i very much doubt the master socket arrestors would either) but certainly enough to resist most spikes caused by lighting in the area.