Cat6 Phone and door bell

[mphillipps]

I've been asked to install a phone line and a second door bell chime into a backyard office. I'm already going to pull a cat6 cable for data through 3/4" PVC ~70'. My question is: can I use a second cat6 cable and run both phone and bell without interference on either cables?

 

[fmtjfw]

I would think so. Besides wouldn't the bell drown out any interference in the phone line?

 

[hbiss]

CAT6 for phone and CAT6 for doorbell. Ever hear of 18/2 thermostat wire????


Can't wait until CAT7 replaces CAT6 or fiber replaces UTP. Guess then you guys won't have any wire to use.


-Hal

 

[__dan]

I've been asked to install a phone line and a second door bell chime into a backyard office. I'm already going to pull a cat6 cable for data through 3/4" PVC ~70'. My question is: can I use a second cat6 cable and run both phone and bell without interference on either cables?

The doorbell is art 725, has to be listed class 2 wire. The phone is art 800, listed CM wire. You may be able to find something dual CM and class 2 rated, but maybe not. Could fail the listing.

Interference, capacitive or inductive coupling between cables run 70 ft in the same pipe is a real possiblity. Especially with voice, any buzzing will be very noticeable, but only when the doorbell is powered on. Type of chime could make a difference. Some bells have an arcing, make break make break, contact which will load the line with RFI. An electronic chime may run pretty quiet. It's a variable.

I would definately run the chime on listed class 2 thermostat wire and if the chime makes the phone buzz, at least the wire meets code.

 

[fmtjfw]

The doorbell is art 725, has to be listed class 2 wire. The phone is art 800, listed CM wire. You may be able to find something dual CM and class 2 rated, but maybe not. Could fail the listing.

Interference, capacitive or inductive coupling between cables run 70 ft in the same pipe is a real possiblity. Especially with voice, any buzzing will be very noticeable, but only when the doorbell is powered on. Type of chime could make a difference. Some bells have an arcing, make break make break, contact which will load the line with RFI. An electronic chime may run pretty quiet. It's a variable.

I would definately run the chime on listed class 2 thermostat wire and if the chime makes the phone buzz, at least the wire meets code.

Cat 6, 5, 4, 3 is telephone wire. Telephone circuit 48VDC and 90VAC. Cat 6,5,4,3,2 is rated at 300V working.

Cat N consists of twisted pairs designed to reject coupled noise at:

6a 500MHz
6 250MHz
5 100MHz

Twisted pair thermostat wire 150V working, no known frequency rating.

 

[__dan]

Cat 6, 5, 4, 3 is telephone wire. Telephone circuit 48VDC and 90VAC. Cat 6,5,4,3,2 is rated at 300V working.

Cat N consists of twisted pairs designed to reject coupled noise at:

6a 500MHz
6 250MHz
5 100MHz

Twisted pair thermostat wire 150V working, no known frequency rating.

I'm not disagreeing with you, I may have seen dual rated cat 6 class 2 wire, but I don't know for sure.

How about the watt or VA power rating. Going from 22 ga. CM to 18 ga. class 2. Phones and network com are signal level, not power level wiring. The chime can be a power level load. Cheap chimes are a soleniod piston that pulls and hits the ringing bar. Voltage drop can be an issue with weak strikes. The chime type makes a difference. Not saying it won't work, just what to look out for.

 

[fmtjfw]

I'm not disagreeing with you, I may have seen dual rated cat 6 class 2 wire, but I don't know for sure.

How about the watt or VA power rating. Going from 22 ga. CM to 18 ga. class 2. Phones and network com are signal level, not power level wiring. The chime can be a power level load. Cheap chimes are a soleniod piston that pulls and hits the ringing bar. Voltage drop can be an issue with weak strikes. The chime type makes a difference. Not saying it won't work, just what to look out for.

If you are worried about voltage drop (I'm assuming you are not worried about overheating with a on cycle of about 5 second and off cycle of say 15 minutes to 24 hours.) then you take the blue, brown, green, and orange wires and twist them together, then do the same with the 4 white wires. You now have 2 #16 conductors with additional surface area.

A typical doorbell transformer is 10V, .5A, impedance protected. #16 should be able to carry .5A forever.

 

[fmtjfw]

And now for chapter and verse.

And now for chapter and verse.

Cat 6, 5, 4, 3 is telephone wire. Telephone circuit 48VDC and 90VAC. Cat 6,5,4,3,2 is rated at 300V working.

Cat N consists of twisted pairs designed to reject coupled noise at:

6a 500MHz
6 250MHz
5 100MHz

Twisted pair thermostat wire 150V working, no known frequency rating.

725.139 Installation of Conductors of Different Circuits in the Same Cable, Enclosure, Cable Tray, Raceway, or Cable Routing Assembly
(D) Class 2 and Class 3 Circuits with Communications Circuits.
(1) Classified as Communications Circuits. Class 2 and Class 3 circuit conductors shall be permitted in the same cable with communications circuits, in which case the Class 2 and Class 3 circuits shall be classified as communications circuits and shall be installed in accordance with the requirements of Article 800. The cables shall be listed as communications cables.

Commo cable is actually a higher rating than Class 2/3

 

[hbiss]

Class 2 and Class 3 circuit conductors shall be permitted in the same cable with communications circuits, in which case the Class 2 and Class 3 circuits shall be classified as communications circuits and shall be installed in accordance with the requirements of Article 800.

Cable is not the same as raceway or conduit. An 18/2 thermostat wire run in the same conduit as a CAT6 communications cable (type CM) does not mean it is considered a communicatons cable.
See 800.133(A)(1)(b)(1)

-Hal

 

[fmtjfw]

Cable is not the same as raceway or conduit. An 18/2 thermostat wire run in the same conduit as a CAT6 communications cable (type CM) does not mean it is considered a communicatons cable.
See 800.133(A)(1)(b)(1)

-Hal

729.139(E)

I am baffled. 18-2 thermostat wire is not magic. Let us use logic for a moment, if a telephone circuit and a class 2 circuit can share the SAME cable, under what circumstances can you explain the hazard to me when the two share the same raceway? It makes no sense.

In addition I may have you at a disadvantage, I've 41 weeks of US Army Signal Corps training on telephony (including repairing central office equipment). I know what voltages and signals occur on telephone circuits.

A standard telephone circuit is energized at 48VDC basically all the time. When a phone is being rung 90VAC 20Hz is superimposed on the DC voltage, possibly run through a diode for ringer selection. In the old fashioned multiple button sets used for intercommunications intercom signalling was commonly a 24VDC circuit to a contact type buzzer (a marvelous electrical noise generator). All this was shipped around in building in telephone station wire and 25-pair cables. CAT-N is just the latest generation of telephone wire.

Barring lightning none of this ever burned down a building.

A doorbell transformer is 5VAC 2A max. It is wound in such a way that if you short the secondary with one inch of #10, the transformer will not exceed its design temperature, day in and day out.

The maximum class 2/3 voltage is 150V, ? the working voltage of CAT-N.

 

[hbiss]

I am baffled. 18-2 thermostat wire is not magic. Let us use logic for a moment, if a telephone circuit and a class 2 circuit can share the SAME cable, under what circumstances can you explain the hazard to me when the two share the same raceway? It makes no sense.

Who said anything about a hazard??

725.139(E) Class 2 or Class 3 Cables with Other Circuit Cables.​

Jacketed cables of Class 2 or Class 3 circuits shall be permitted in the same enclosure, cable tray, or raceway with jacketed cables of any of the following:

1) Power-limited fire alarm systems in compliance with Article 760

2) Non-conductive and conductive optical fiber cables incompliance with Article 770

3) Communications circuits in compliance with Article 800

-Hal
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[fmtjfw]

Who said anything about a hazard??

725.139(E) Class 2 or Class 3 Cables with Other Circuit Cables.​

Jacketed cables of Class 2 or Class 3 circuits shall be permitted in the same enclosure, cable tray, or raceway with jacketed cables of any of the following:

1) Power-limited fire alarm systems in compliance with Article 760

2) Non-conductive and conductive optical fiber cables incompliance with Article 770

3) Communications circuits in compliance with Article 800

-Hal
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Ok, Hal, I'm a thick headed old man.

What was your point about 800?
Are you agreeing that a class 2/3 circuit can be in the same raceway as a communications circuit in a CAT-6 cable or not?
Are you suggesting that the telephone circuit does not fit the requirements of 800?
725.139(D)(1) says that a class2/3 circuit in the same cable as a communications circuit shall be classed as a communications circuit.
725.139(E)(3) says that a class 2/3 circuit in a jacketed cable shall be permitted in the same raceway as a communications circuit (and I guess the class 2/3 is not a communications circuit in this case).

 

[hbiss]

I think you are confusing or not understanding the difference between conductors in a cable and cables in a raceway/conduit.

A cable is composed of conductors within or under a jacket. What Art 725.139(D)(1) is saying is that suppose you have a multi-conductor cable like a CAT5 and you use 1 pair for telephone then you use another two conductors for a CL2 doorbell circuit. The CL2 circuit gets reclassified as a communications circuit and now Art 800 applies to both circuits (not that it makes much difference) because the two circuits are contained within the same cable under a common jacket.

Now, we have a conduit and we pull a CAT5 for data or telephone and an 18/2 for a CL2 doorbell circuit. These are two separate cables within a conduit and Art 725.139(E)(3) applies. The CAT5 is a communications cable under Art 800 and the 18/2 remains a CL2 circuit under Art 725.

Get it?

-Hal

 

[fmtjfw]

GOT IT! THANKS

GOT IT! THANKS

I think you are confusing or not understanding the difference between conductors in a cable and cables in a raceway/conduit.

A cable is composed of conductors within or under a jacket. What Art 725.139(D)(1) is saying is that suppose you have a multi-conductor cable like a CAT5 and you use 1 pair for telephone then you use another two conductors for a CL2 doorbell circuit. The CL2 circuit gets reclassified as a communications circuit and now Art 800 applies to both circuits (not that it makes much difference) because the two circuits are contained within the same cable under a common jacket.

Now, we have a conduit and we pull a CAT5 for data or telephone and an 18/2 for a CL2 doorbell circuit. These are two separate cables within a conduit and Art 725.139(E)(3) applies. The CAT5 is a communications cable under Art 800 and the 18/2 remains a CL2 circuit under Art 725.

Get it?

-Hal

filler

 

[Jerry the Phone Guy]

Sorry if I'm late to the table, here (I must log in more often), but my two centavos are that this is a poor design just asking for trouble. Doorbells typically draw close to 1 amp when actuated, so that pulse will probably be induced into the phone line. This would be a problem whether the bell circuit is carried over 'bell wire' or Cat 6 (much less induction using a single pair of Cat 6, though). However, if you use Cat 6, voltage drop might be an issue, as well (23 gauge having much higher R than 18 or 20). If you common the 4 pairs together as suggested, then you lose much of the humbucking provided and give yourself a rather messy splice at each end. (This could also be considered a violation of 'neat and workmanlike' NEC 800.24; it's certainly a violation of common sense! Is Cat 6 that much cheaper than bell wire?) Another problem could crop up down the line, when they change doorbells to a noisier, higher-current type.

Let me ask a dumbass question: Why are these cables being run in conduit? I'd suggest ditching the conduit, if possible and running them with at least 2 inches separation OR running just the bell wiring outside the conduit (but not supported by it as that would be a violation).

 

[fmtjfw]

I performed an experiment:

I performed an experiment:

Sorry if I'm late to the table, here (I must log in more often), but my two centavos are that this is a poor design just asking for trouble. Doorbells typically draw close to 1 amp when actuated, so that pulse will probably be induced into the phone line. This would be a problem whether the bell circuit is carried over 'bell wire' or Cat 6 (much less induction using a single pair of Cat 6, though). However, if you use Cat 6, voltage drop might be an issue, as well (23 gauge having much higher R than 18 or 20). If you common the 4 pairs together as suggested, then you lose much of the humbucking provided and give yourself a rather messy splice at each end. (This could also be considered a violation of 'neat and workmanlike' NEC 800.24; it's certainly a violation of common sense! Is Cat 6 that much cheaper than bell wire?) Another problem could crop up down the line, when they change doorbells to a noisier, higher-current type.

Let me ask a dumbass question: Why are these cables being run in conduit? I'd suggest ditching the conduit, if possible and running them with at least 2 inches separation OR running just the bell wiring outside the conduit (but not supported by it as that would be a violation).

"close to 1 amp" -- typically doorbells are rung for 30 seconds or less. Not enough time for the wire to even warm. Typically off for 15 minutes to 1 day.

#24 5.25 ohms/100ft 3 paralleled 1.75/100ft 4 paralleled 1.3/100ft

Messy -- picture to follow on another post

Experiment:

148 feet of cat5/cmp cable. 4 pair 24awg solid. (scrap laying around)

At each end connect orange, green, and brown; and or/white, gr/white, and br/white.

near end 24VAC class 2 transformer (just something laying around)
near end Triplett "The Fox" toner use for talk battery
far end 1A2 intercom buzzer, Harris ts19 BUTT SET

connect fox to bl-bl/w
connect buttset to bl-bl/w
connect transformer to o gr br and later o/w gr/w br/w
connect buzzer to o gr br and o/w gr/w br/w

Turn fox to talk
turn buttset to talk
>>> silence. clicking when connect/disconnect talk battery
connect transformer to o/w gr/w br/w
>>> buzzer sounding
>>> no sound on buttset
disconnect transformer
>>> click when disconnecting transformer.

"why cat 6" only have to carry a single CMP cable on the truck, use it for ethernet, telephone, door bells, door lock circuits ....

"why conduit" If you want to replace the signal conductors, putting them in a conduit will preclude having to dig up the lawn again.
Conduit is underground so supporting is not an issue.

 

[G._S._Ohm]

Don't NMS and hybrid cables for home automation mix signals and power all the time?

 

[fmtjfw]

Messy?

 

[don_resqcapt19]

The doorbell is art 725, has to be listed class 2 wire. The phone is art 800, listed CM wire. You may be able to find something dual CM and class 2 rated, but maybe not. Could fail the listing. ...

It doesn't have to be dual rated. Type "CM" is a permitted sub for type "CL2". See Table 725.154(G).

 

[haydenjsle]

Another option--you could elminate the second chime and use one of these systems with a single CAT6 run. ....someone presses the front doorbell/station and it rings a distinctive tone over all the house phones---pick up any house phone and you have 2 way intercom to the person pressing the doorbell/station. They also have optional modules with dry contacts to activate a basic doorbell system or with built in discreet analog cameras.

Sounds like the house is existing and the office is a new addition. If so, you would have to replace the existing house button with one of their door stations and rewire direct to the module.

Maybe not the most cost effective approach, but would eliminate wire concerns and have some benefits--for you as an upsell and homeowner as an intercom.

http://www.doorbellfon.com/PDF cutsheets/DP28-C cutsheet.pdf