atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Maximum distance for dial tone and ring tone?

We have a ranch where we are going to install a Doorking gate intercom unit. It's about 2700' away from where the main house and where the phone system is. If we ran cat3, would dial tone make it that far and would ring voltage make it back to the KSU?

Dial tone and ringing voltage (POTS) goes many, many miles over standard copper cable pairs. What kind of CAT3 cable are you planning on running for half a mile? Are you talking about outside plant cable or just running inside wire in conduit?

The real key is what the manufacturer's specs mandate. Most any POTS application on a system is good for several thousand feet, with a very hefty overhead to allow for variables.

You'll be fine in my book with any kind of twisted pair cable.

I would like to butt in here and tell you that using "cat3" (unless it's direct buriable, shielded cable) would be a mistake.

You need to use 6-pair, filled BSW (buried service wire) that has water-resistant gel and a metallic shield that can be grounded and bonded at both ends.

I have worked on many gate systems that were installed with other types of wire and the results were not pleasant.

For one thing, if an unshielded control cable is buried in the same trench with the line voltage that controls the gate hydraulic motors, emf pulses in the line wires will be induced into the control wires and cause erratic operation.

Since the NEC requires that all communication conductors entering a building need to be bonded and grounded, it makes sense that the cable's shield be bonded, too. This is to keep lightning strikes from entering the house and frying your telephone system.

As to your question, the best answer will always be found in the text of the manufacturer's instruction manual, where it states the loop resistance limitations of the Door King system. BSW can be purchased in 22 gauge, which has a resistance of 16 ohms per thousand feet, and as Ed has said, telephone service runs for miles on 22- 24- and 26-gauge twisted pairs, I suspect that a half mile of BSW will not present a problem.

See pages 11 and 12 in the following document. It specifies that only gel-filled BSW be used, and it indicates the maximum loop lengths for various gauges of wire. It also shows a diagram of the recommended separation of line and control wires.

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It sounds like you plan on using an anolog ext. on a phone system? If so, you need to check the loop limits on said phone system. Most are 1000 feet.
If you plan on running CO dial-tone from the house to the gate you need to double the distance to get there and back. That puts you about 1 mile in cable distance. The door Kings wire in series on DT. You may want to make sure there is no DSL on the line also.

Was planning to run buriable cat3 cable, after having so many problems with indoor cable ran undergound in conduit, we only run buriable now when going ug. After reading the Doorking manual like you guys said, I'll follow their specs and run buriable cat5e 18 guage. Does that even exist though?

No, it doesn't exist.

I don't know why you're hung up on Cat anything. The higher the category number, the more twists and therefore more copper wire per running foot of cable. You are adding more total loop resistance as the category gets higher.

You can use 6-pair 22 gauge BSW, as recommended. If you find that there is too much resistance, double up on the pairs.

Since the cable is being used for just one talk circuit, the crosstalk that might occur when doubling the copper is irrelevant.

Go with Arthur, he's giving you good advise. Although the other solutions will work also.

OK got it, thanks fellas...

astro,
The reason Doorking is recommending CAT5 is that their IT people throw that expression around as THE BEST WIRE THERE IS, and for networking, it is, or was. Since they don't know any better, maybe you need to 'splain the facts of life.

You have to remember that CAT5 and higher are DATA cables designed for ethernet applications. As part of the dumbing down of the industry to accommodate IT people, sparkies and DIYrs, CAT5 and CAT5e have become the defacto low voltage wire for anything from doorbells, thermostats, speakers, telephone, LV lighting, etc. It's kinda like RJ45 being used to describe all 8 pin/8 position plugs or jacks.

I have to laugh about how that Door King manual goes on about CAT5e yet it recommends 18ga for 3600 ft runs. Guess that they don't know that the wire gauge is critical to the category spec so CAT5e can only be 24ga. There are cables available that are much better suited for this than trying to use a data cable.

-Hal