atcomsystems.ca/forum Forums Thread Like Summary - buzzing induced on analog phone system

I have an outbuilding with direct bury cat-5 cable connecting the outbuilding to the main-building.The
distance of the run is about 630ft. We are using a Panasonic KX-TG9582G Dect 6.0 wireless system in the main-building and have AT&T wired hand-sets in the out-building.

Whenever this wire is punched down into the 66 block with the rest of the extensions, we get an audible buzz on the line from any extension in the main-building and the outbuilding. I thought it may be grounding related, but i am not sure.

I tested continuity of the pairs and there is no cross wired or shorts between the pairs and i tried different pairs with the same result.

Any help would be appreciated!

Bob

Without it having a conductive sheath you can't. Don't know how it can be called direct buried without a sheath. Rebury with the correct type of cable and give more clearance from the power if that's what you decide. Running parallel to power is never a good idea even with a good sheath, especially that distance. You could try grounding all the unused pairs, don't know if that would do it or not worth a try.

Are you sure you're using the correct white and the correct blue* to form the pair that is in use? If not, then you're using a split pair, which causes imbalance. Even without the AC power proximity, 630' of an unbalanced pair will pick up all kinds of noise, even nearby radio broadcasts!

* Or any other base color.

Many manufacturers of OSP cable, even drop wire, do not include a tracer mark on the whites to identify their matching base color forming a pair. You may be using the white that goes with the white/brown pair (or any of the others). Yes, it will work, but it will be noisy. You said that you checked for continuity on all pairs, but that just means that <a> blue and <a> white make it through.

Lastly, some Bell companies in the Southwest bury non-shielded drop wire due to their arid climates and soils, but that's the exception, not the norm. I've seen direct-burial CAT5e cable both in shielded and non-shielded varieties, but the shield is more of a copper foil. Regardless, grounding is NOT your issue. most ground faults on a working pair will cause all kinds of trouble, not just hum.

That's a good point to mention, Hal. It is true that output ports on IADs, VoIP ATAs, EMTAs and other telephony toys are often used to emulate a real POTS line, but they often don't work.

I had an installation that called for the reuse of a pair in an existing 300 pair aerial cable to send a POTS line from an EMTA. This pair had carried a digital station on a Nortel system to a regular jack. It didn't take long to determine that Spectrum Cable's Arris EMTA lacked the horsepower to push clean dial tone that far. We obtained Viking Electronics' TBB-1B, which is a great per-line device that was developed specifically for these situations. Of course, you will need one per line.

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