Re-wiring phone, but what it this?

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philh

2 posts

Wannabe Geek

#23188 21-Jun-2008 11:22

Hi

I am looking to rewire the phone system in our house, but first want to know what this thing is?

http://www.flickr.com/photos/14215944@N05/2595747201/

This device is mounted in the hallway by the ceiling. There is a black cable running from the demarc point into it. There is a bare copper wire which runs back up into the ceiling but which is just cut off - presumably it was some sort of earth? A grey cable then comes out of the device and runs halfway down the wall to what seems to be a juntion box from which a white cable runs to the the phone jacks.

I am looking to install a ADSL filter and then run new sockets and cabling around the house.

My questions are:

- what is this device
- what does it do
- does it need to stay
- can I shift it into the ceiling
- where does the filter sit in relation to it.

Thanks in advance

sbiddle

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#139554 21-Jun-2008 12:20

It is a lightning/surge arrestor from the old days before digital exchanges.

You can safely bypass this and probably should do as they can interfere with ADSL.

Samsung

Shop now on Samsung (affiliate link).

AmooMan

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#139556 21-Jun-2008 12:27

Ohh thanks sbiddle ...

I always wondered what that thing was :)

Cheers

hellonearthisman

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#139568 21-Jun-2008 13:53

Cool, I just had to post the picture.

Bung

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#139579 21-Jun-2008 14:41

sbiddle: It is a lightning/surge arrestor from the old days before digital exchanges.

More correctly from the days before underground cable.

philh

2 posts

Wannabe Geek

#139600 21-Jun-2008 16:59

Thanks for your replies.

Forgot to mention, we are still connected by overhead cables, so can we get rid of it given its for lightening protection?

Cheers

PS Hellonearthisman - How did you paste the photo in? Tried using the Insert/edit image button but couldn't get it to work.

rumpty

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Master Geek

#139635 21-Jun-2008 21:45

philh: Thanks for your replies.

Forgot to mention, we are still connected by overhead cables, so can we get rid of it given its for lightening protection?

Cheers

I would leave it in circuit. The two ceramic tubes are fuses. Just take them out and give the contacts a clean before replacing. I don't think they should upset the ADSL signal.

grant_k

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#139637 21-Jun-2008 22:32

There are 2 questions that nobody has answered yet:

philh: My questions are:

- can I shift it into the ceiling
- where does the filter sit in relation to it.

Yes, you could shift it into the ceiling, but the reason for placing it up near the ceiling is that it is much easier to replace the fuses if they blow. That could conceivably happen in the event of a lightning strike, although it is unlikely that your router would survive such a hit

So, I would suggest leaving it where it is.

Secondly, you would be best to wire your filter AFTER the fuses i.e. at the junction box where the grey cable is joined to the white cable further down the wall. That would be the tidiest place to do it and probably easier to get at than up in the roof.

Bung

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#139638 21-Jun-2008 22:52

If the copper wire is cut short or as in the photo the carbon blocks are missing, it is basically now just another connection to go bad. I'd get rid of it.

grant_k

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#139639 21-Jun-2008 23:00

Bung: If the copper wire is cut short or as in the photo the carbon blocks are missing, it is basically now just another connection to go bad. I'd get rid of it.

Yeah, I thought there was something missing just above the metal block at the bottom.

The carbon blocks go between the metal block and the spring fingers connecting to the bottom of the fuses don't they?

Wasn't there also a Spark Gap included somewhere in these Lightning Arrestors?

Bung

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#139643 21-Jun-2008 23:10

grant_k: The carbon blocks go between the metal block and the spring fingers connecting to the bottom of the fuses don't they?

Wasn't there also a Spark Gap included somewhere in these Lightning Arrestors?

The carbon blocks formed the gap.

hellonearthisman

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#139677 22-Jun-2008 09:24

philh: Thanks for your replies.

Forgot to mention, we are still connected by overhead cables, so can we get rid of it given its for lightening protection?

Cheers

PS Hellonearthisman - How did you paste the photo in? Tried using the Insert/edit image button but couldn't get it to work.

I have firefox, I go to flickr and right click the image size I want, this present the firefox menu with the option to copy image location.
That copies the location of the image n your clipboard. In the Geekzone editor is a picture of a tree, clicking it present a box asking for picture location URL, paste your image into there. and OK, image is now in post.

You night want to go back to the flickr site and copy the flickr image url that you copied the image from. url to image in clipboard.
So in the Geekzone editor, clicking on the image (if it loaded propper) then click on the chain, this will add a link, paste the url from the clipboard. Ok.

The 2nd part isn't needed but fits better with the flickr rules.

Or you could select the content you want to use, by using your pointer to select the area you want to copy. And when it's highlighted, press CTRL-C to put it into the clipboard and then paste into the Geekzone editor.

cyril7

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#139682 22-Jun-2008 10:17

Even in Aus where lightning is a much larger issue than our narrow isles arrestors like above are no longer used. General concensus is that they do/can effect DSL performance, and modern ADSL electronics (and phones/faxs) just gets blown away before such arrestors make an impact, its better to just ensure you have your insurance will cover things. Any lightning protection is only good for protecting against impulse spikes due to induction from nearby hits, if your line takes a direct hit, its all over rover no matter what protection you have.

As has been pointed out there is no discharge gap, so what you have here is just a bad joint waiting to (if not already) upset your DSL performance, get rid or it.

If you still want some protection for your DSL/PC gear then get a power plug strip with built in surge protectors that includes a DSL capable phone line one, this will have a pair of modern gas arrestors, and probably a couple of bulk semiconductor Trisils that will have a better chance of protecting your gear, something like this. Just ensure it does not have filtering that will effect ADSL performance.

Cheers
Cyril