Phone line Fuse ?

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D33ZZ

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#19484 19-Feb-2008 08:39

Hi we have old house and this thing has been there ever since for the phones as I can see the wires going to the phone sockets .

Is this still needed ? Is there a better option? Can the old wires and that fuse thing affect my line noise

old3eyes

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#111535 19-Feb-2008 09:34

Do you still have a pole feed to the house in a metro area?? I had one of these when I moved into my current house in 1995. I pulled out the fuse and the line was still live so at some stage it had been by passed so removed the fuse mount. Unless you live way out in the country with open wire pole feed that is subject to lightning strikes they are redundent..

Regards,

Old3eyes

sbiddle

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#111541 19-Feb-2008 09:57

They are actually a surge arrester from the old days with manual exchanges and are pretty much redundant these days. I believe they may also cause some performance hits with ADSL as well but somebody a bit more knowledgeable maybe able to confirm this.

grant_k

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#111550 19-Feb-2008 10:51

sbiddle: They are actually a surge arrester from the old days with manual exchanges and are pretty much redundant these days. I believe they may also cause some performance hits with ADSL as well but somebody a bit more knowledgeable maybe able to confirm this.

This old-fashioned Lightning Arrestor box contained a fuse in series with each leg of the line, plus in some cases a spark gap inside a little ceramic gizmo. The idea was that in the event of a lightning strike, the fuses would blow and protect your telephone.

This kind of approach had some merit in the days when telephones didn't contain any electronics, but nowadays all phones do, and so they would be completely fried by the lightning, before the fuses had a chance to blow x number of milliseconds later.

No worries, you just get a new phone at The Warehouse bro

But in those days, phones cost Telecom a lot of money, and most subscribers had overhead lines, so it was worth putting in the lightning arrestor.

Now -- Back to the Future and you are trying to run ADSL through this piece of 1930s technology...

The fuses and associated wiring of the box will definitely cause a "step" impedance change in the line, which is prone to cause reflections and hence reduce your maximum possible ADSL speed.

So, unless you still have overhead lines, I would recommend removing it completely and joining up the incoming and outgoing lines as neatly as you can.

If you still have overhead lines, there may be some merit to keeping the box intact as it could possibly prevent damage to the internal wiring of your house in the event of a lightning strike. However, if this happens, your ADSL router and phone would be fried anyway; it is just the internal wiring (past the Lightning Arrestor) that would be protected. It's your call in this case, as to whether you remove the box for extra performance and take the risk of wiring damage, or not.

D33ZZ

36 posts

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#111558 19-Feb-2008 12:34

Thanks guys will remove it and link the wires hopefully notice some little bump on my adsl sync speeds saying that is it normal for sync speeds to drop when phone is plugged in as I get much better syncs without the phone plugged in.

grant_k

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#111563 19-Feb-2008 12:49

D33ZZ: ...is it normal for sync speeds to drop when phone is plugged in as I get much better syncs without the phone plugged in.

May be a silly question, but have you got a filter plugged in to the wall socket with your phone plugged in to the filter's BT socket?

D33ZZ

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#111570 19-Feb-2008 13:23

Hi yes external filter (Dlink) sync rates raise when phone is unplugged vs lower syncs with phone plugged into the filter.

grant_k

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#111571 19-Feb-2008 13:28

D33ZZ: Hi yes external filter (Dlink) sync rates raise when phone is unplugged vs lower syncs with phone plugged into the filter.

It sounds like that filter is faulty then. There might be some minimal change in sync speed, but if it's more than 1 or 2%, I would suggest replacing the filter.

What are your Sync Speeds with and without the phone plugged in?

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D33ZZ

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#111576 19-Feb-2008 13:41

First 3 images with phone connected to the filter , last 3 images with the phone unplugged.

grant_k

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#111579 19-Feb-2008 13:57

Hmmmmm, it's interesting that your Upstream Sync. Rate is the one that's mostly changing, whereas your Downstream and Attenuation/Signal-to-Noise etc are staying pretty much the same.

I think what you are seeing here is the effect of a poorly-designed filter on the Upstream channel which uses frequencies just above the audio band.

I would say that your filter does not have enough poles in its design (a means of saving cost) therefore the cutoff rate is too gradual and you are losing some of your upstream bandwidth.

I would recommend buying a proper Marque Magnetics Filter at MasterTrade. Cyril7 posted the details in a recent thread. If you can't find it, post back here and I will hunt it out for you.

The MM Filter, costs between $50 and $80 (IIRC) depending on whether you get Trade Price or not. It needs to be hard-wired as near as possible to the Telecom Demarc Point with all phone sockets in the house being connected to its output. All other filters can then be removed, and your ADSL router is connected across the input to the filter.

Once this has been done, you should be getting similar Upstream Sync. Rates to what you are currently seeing with the phone unplugged.

coffeebaron

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#111588 19-Feb-2008 14:20

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D33ZZ

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#112041 21-Feb-2008 11:24

Hi thanks by anychance is there any good external line filters , like the good ACS ones I hear in oz ?

cyril7

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#112056 21-Feb-2008 12:12

The ACS filters are specific to the australian market and designed to match the termination provided by their DSLAMs, this is not quite the same as Telecoms ones.

The only external filter certified for use in NZ is the Marque Magnetics MM3200B as linked by CoffeeBaron above and exceeds all requirements of the specification. It is the one Telecom will install if you have there contractors come and install a central filter.

The Aquire price is good, you will also need some Scotchlok gel crimps to install it.

Cyril

D33ZZ

36 posts

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#113757 29-Feb-2008 12:46

As I will be removing that block and upgrade the wiring what cable wire should I be using straight from into the house then to phone socket? coming into the house is 2 copper wires. I hope that makes sense lol.

grant_k

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#113760 29-Feb-2008 12:53

D33ZZ: As I will be removing that block and upgrade the wiring what cable wire should I be using straight from into the house then to phone socket? coming into the house is 2 copper wires. I hope that makes sense lol.

I would use some Cat5 (4-pair) network cable, it's very cheap and readily available.

There are some places that still have Cat3 cable (2-pair) as used by Telecom, but it's harder to get and often more expensive.

cyril7

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#113762 29-Feb-2008 12:59

As Grant says, a run of Cat5, it is practice to use the blue pair for line1.

Cyril