Telephone extension - two ringing caps?

The telephone extension wiring here appears to be a bit odd.

One of the extensions, with the wire buried in plaster, died recently - I suspect it got wet with the recent flooding, and we started getting noise on the line. It's currently been disconnected from the master, and the line is all nice and clear at the moment, phones connected elsewhere happily ringing away.

I was going to put another wire in, which would be a simple enough process. Except when I've pulled off the faceplate (genuine BT extension plate, not the master socket type with the removable front), I've discovered it's got the capacitor, resistor and surge protector of a master socket.

I'm now wondering if I should :

a) Just wire it in with pins 2,3,4,5 as normal and not worry b) Get a plain faceplate c) Modify this one by disconnecting the various components leaving just pins 2+5 connected.

Any thoughts?

(ADSL is filtered off at the master socket with a faceplate - can't be doing with having individual filters for each phone and the potential for any dodgy extension wiring to screw up the broadband)

Reply to
Clive George
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it doesn't matter if you have a master faceplate used as a secondary, either way works fine

Usually cable is ok after flood, it's waterproof after all, except the ends which may need a clean & reconnect.

NT

Reply to
tabbypurr

And having two masters on the same circuit, which is what I'd end up with?

Yes, that is what I'd have expected, but the ends are fine and cutting that bit out of the circuit did fix the problem. I expect there's some damage somewhere in the buried bit which has finally corroded through.

Reply to
Clive George

Is it waterproof? All the phone wiring in the BBC White City building had to be replaced because the cable ducts (in the basement car park) filled with water. There are obviously differnt grads of cable.

Reply to
charles

It presumably worked ok prior to the flood? You're not supposed to have a master socket where there should be an extension socket, but it's not a disaster.

I think I would chop through the legs of the capacitor and resistor so as to convert it to an extension socket. Then connect 2, 3 and 5. It

*may* work with just 2 and 5 depending on whether the phone you use needs a ring signal on 3 or generates its own. 4 is never used.

Alternatively, keep it as is, but just connect 2 and 5. If your phone

*does* need a ring signal on 3, it will then be provided by the built-in capacitor.
Reply to
Roger Mills

You would only need 2 and 5, ignore the others. 4 is nearly never required in domestic installs, and 3 is better regenerated at the socket by a local cap, than wired round the house if you have ADSL, since the unbalanced wire tends to acquire extra noise.

Less good than (a) but would work.

You could lose the resistor and surge arrestor if you wanted.

So having the rest of the house as a two wire installation would actually be preferable.

Reply to
John Rumm

Ta for the reassurance. I've now done two wires to that socket, and everything is working.

Reply to
Clive George

yes, it's fine

NT

Reply to
tabbypurr

PVC is, yes. So is rubber. So are the LSOH types. Those account for close t o 100% of domestic cables. If you have ancient DCC then no. If you have MIC C with unsealed ends then that isn't either, but it can be dried out.

Had to according to who? The sparks that wanted the job or the luvvies that were easily persuaded? If you have junction boxes among the ducts those wo uld need a clean out. Co-ax can get water inside and lose performance, but phone wiring isn't done with co-ax operating at UHF.

Sure. They're all waterproof.

NT

Reply to
tabbypurr

For a short term (FSVO "short term") measure and non-mains that might be satisfactory. Trouble is capillary action draws the water into the cable both between the insulated conductors and conductors and their insulation. Over time this causes corrosion of the conductor at signal levels that degenerates to nosie/open circuit. At mains with a bit of load a "hot spot" in the cabling...

If the insurance companies felt it wasn't required to strip out all the cabling after a place has been flooded they wouldn't pay for it. Went to an electrical wholesaler in Hexham just after the December floods, they were only flooded to 18" or so but any brand new cable that had go wet was out in the shipping container to be chucked out, along with anything else that had got wet.

Reply to
Dave Liquorice

During construction of the HSBC HQ building in Canary Wharf a water main in the plant room on the roof fractured and many thousands of gallons of water ran down through the building. The underground car parks were flooded, but more importantly, water ran down the cable voids and filled up under the suspended floors. The network cable manufacturer stated that they didn't believe it would cause problems, but that they would not honour the warranty on the cable. It all had to be replaced. It's a 41 storey building, with Europe's largest trading floor in it.

(And everyone apart from the networking guys was quite pleased, secretly, since it gave 3 months breathing space to catch up with all the backlog.)

Reply to
Huge

Wimps, the roof was ripped off the system X exchange in St Vincent during a hurricane and it carried on working with no problems. A bit of water is no problem.

Reply to
dennis

Look at it from their point of view

- On the one hand there is a small (but non-zero) risk they will be on the hook to replace the cabling.

- On the other hand they get a big new order.

which one do you *think* they are going to take?

Reply to
Martin Bonner

Industry has wet washed electronics since at least the 1960s. It's ok at an y voltage. I've personally wet washed things upto 25kV without problem.

Insurance companies IME seem to have little practical knowledge of houses, they are more in the money business. They pay consultants who look to cover their arse against every imagined eventuality, against that one time in th eir working life when they might not have recommended enough be done. I don 't need anywhere near that level of certainty, and unlike those consultants it does cost me to overdo things. Hence they routinely recommend work that does not need doing. One sees that often when it comes to house buying tim e.

NT

Reply to
tabbypurr

At BBC TV Centre, 'Scopes got washed - but the secret was in the drying, not the washing. Some water - particularly in then SE of England will leave deposits behind when it is dried off. Those could easily short PCB tracks. The kit that we washed had no such modern concepts. Simp;y ceramic valve bases and tag strips.

Reply to
charles

A slightly different situation. That trading floor (and it's associated back office staff) turns over about $3Tn a day. Would you be prepared to endanger that?

I wasn't involved in the decision, but had I been, I'd have gone with replacing it.

Reply to
Huge

Trivial, people die when the phones don't work.

Reply to
dennis

People die - sometimes, when phones work - that death can be postponed

Reply to
charles

Live, under load? Kept wet in use?

For kit than has got a dunked be that sea water, "fresh" water, loo pan water, I have no qualms at all about wiping the batteries out, removing as many covers and casings as possible and shoving the whole lot under a cold tap or flushing with with (plain) bottled water. Then keep it in a plastic bag until the first opertunity to start drying it off properly arises. Once dried as much as possible, it'll sit somewhere nice and warm for a couple of days before being repowered.

This is not the same as water that has crept 20' down the inside of a cable with no hope of getting out and remember PVC insulation isn't an oxygen barrier. The corrosion won't be fast, time scale of years, but it will happen.

Ah the "Home Buyer Survey" biggest bit of arse covering documention ever.

Reply to
Dave Liquorice
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Yep. When the lights on my trailer packed up due to corrosion, I couldn't find a good bit of cable to cut back to. I ended up replacing about 4 feet of wire because the moisture had tracked back down it.

Reply to
Huge

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