Thread: Modem Protection

Where the telephone line comes into the house there is a junction box on the wall.
This box has a wire going to earth.
I presume this is for protection in case there is a voltage spike.
Does this provide any protection to my modem?

The reason I ask is that the TOT repairman came round yesterday and he has bypassed the box.
The incoming line is now connected directly to the RJ11 socket.
Should I leave it like that ?

Originally Posted by Thetyim

The incoming line is now connected directly to the RJ11 socket.

Take the whole lot outside and burn it.
The bastard TOT man probably works for the CIA.

Originally Posted by Norton

Ground is for shield on incoming phone line

Phone lines are not shielded..

The ground is there for the lightning protector which has a spark gap where high voltage can jump over to ground instead of continuing into your house and fry your telephone or modem.
The lightning protector often cause problems especially if it has served its purpose during a thunderstorm but also because of humidity and dirt.
I've yet to see a Thai telco serviceman replace the lightning protector, they usually either remove the ground line or connect cables together outside the box.

Originally Posted by lom

Phone lines are not shielded..

I had CAT5 shielded in house but stand corrected. Incoming phone lines unshielded.

My TOT line and the incoming mains electric live are all of 25mm apart,and run parallel with each other to the street lamp pole!

Originally Posted by crippen

My TOT line and the incoming mains electric live are all of 25mm apart,and run parallel with each other to the street lamp pole!

It's so you can coil other cables around the mains cable. That's good in Thailand...

Originally Posted by lom

The ground is there for the lightning protector which has a spark gap where high voltage can jump over to ground instead of continuing into your house and fry your telephone or modem.

These same boxes have been in use since before computers were common.
I guess they were devised to protect the phone and anyone using it.
Do they give any real protection to the modem ?

Originally Posted by Thetyim

Do they give any real protection to the modem ?

no

some UPS's will have a rj11 in and out and claim protection -

Originally Posted by Thetyim

Do they give any real protection to the modem ?

Rarely, maybe if a lightning hits the cable at a far distance but usually they don't react quick enough to protect a modem.
It is also the first component to suspect if your phone line is bad (leaking to ground) so it is often removed.

^ & ^^
Thanks.
I will leave the box out and hard wire the line directly into the rj11 socket.
Does it have to be any special cable.
Can I use 2 x 1.0 sq mm ?

Originally Posted by Thetyim

Can I use 2 x 1.0 sq mm ?

Yes it will work.

twist it for best results - I think twisted pair instrument patch wiring is about 8 twists per 100mm - but no need to be too anal about it

but if it is sheathed it is not really worth the effort to strip the sheathe and twist the pair

^ The phone wire they hang in the concrete poles is 2 x 0.5mm copper single core + 1 x 1mm stainless support (carrier) and it is not twisted anywhere
That wire is in Thetyims case prolly somewhere near 1km long so a short piece of 2x1 sq electric cable wont make it worse. Twisting will do fekk nothing..

^
Yep.
I am about 3.5km from the DSLAM
I will only be adding 8 metre to the end

You can buy a surge protector in Panthip etc

^
For mains input or for telephone line ?

Got a link?

most UPS will provide an additional port for RJ11 protection,

certainly for mains
I got mine in Kampheang Phett at shop nr roundabout must be easy to find in Bangers

^
I'm not interested in one for mains.

Only an RJ11 surge protector