Cat5 for doorbell?

[gene6]

Greetings group, when making the order for wiring some new homes I put on my parts list 18/3 doorbell wire.
My coworkers are saying they just pull cat5.
I have always been under the impression that signaling circuits have to be at least 18AWG and cat5 or 6 is for communications circuits.
I took a look at 725 but not finding anything other than 18 being a minimum for class 1.
So did things change? Is it fairly standard to use 23 AWG on a class 2 doorbell transformer?
Code references please.

 

[LarryFine]

I've always used 2-conductor T-stat wire.

 

[tthh]

Go with Cat5 and land it somewhere that the Internet servcie is going to available/accessible. Many people want video doorbells and if you have Cat5 you can get that done without batteries and without WiFi.

 

[zbang]

Sometimes it's easier to keep and use CAT5 than multiple spools of other wire.

(Code won't tell you "standard", which can change in different parts of the country, it'll only tell you what's allowed or not. If 725 says that 18g is needed for Class 1 and doesn't say anything similar for 2, then it's not prohibited.)

 

[jaggedben]

Assuming it's a class 2 or 3 circuit see 725.135. I don't see Cat-5 mentioned. Of course 'Cat-5' is a designation for UTP signal quality, it's not an insulation type. Is there Cat-5 that is cross listed? If so I'm betting that's not what they used.

There's both a size and an insulation type question here. What I think is clear is that this is not an intended use of UTP.

(Edited, wrong code reference at first.)

 

[hbiss]

Go with Cat5 and land it somewhere that the Internet servcie is going to available/accessible. Many people want video doorbells and if you have Cat5 you can get that done without batteries and without WiFi.

I have always been of the mind that you use data cable for data and not for things like doorbells and thermostats or even phones. Nothing like trying to follow a thermostat wire in a house full of other blue CAT5s. But now things have changed and nearly everything is ethernet so it does make sense to use CAT5 even if it's not going to be used at it's full potential at the moment. I'm also a great proponent of not using WiFi if you can help it.

-Hal

 

[jaggedben]

See also table 725.144.

 

[gene6]

I've always used 2-conductor T-stat wire.
View attachment 2566122

Thanks for the replies this is what I have always ran brown or white jacket 18/2 or 18/3 copper.

See also table 725.144.

Ahh ok Ill look that up I don't have my code-book with me in the truck today.
The transformer is a Hammond BE2F 16.5V 40VA so I presume it can output 2.4 Amps continuously.
I am not sure at what amperage the impedance cuts it off.

Go with Cat5 and land it somewhere that the Internet servcie is going to available/accessible. Many people want video doorbells and if you have Cat5 you can get that done without batteries and without WiFi.

Thats not a bad idea, I'd be tempted to run both that and a 18/3 though. I am unsure about hooking cat5 up to a doorbell transformer.

 

[hbiss]

Assuming it's a class 2 or 3 circuit see 725.133. I don't see Cat-5 mentioned. Of course 'Cat-5' is a designation for UTP signal quality

If you look at the jacket and spool or box label, data cable is listed as type CMP/CL2. "Communications multipurpose and Class 2."

You are free to use it for any CL2 application.

-Hal

 

[wwhitney]

Assuming it's a class 2 or 3 circuit see 725.135. I don't see Cat-5 mentioned. Of course 'Cat-5' is a designation for UTP signal quality, it's not an insulation type. Is there Cat-5 that is cross listed? If so I'm betting that's not what they used.

Any Cat-5 that is installed in walls needs to meet the requirements of 725.135, so it definitely exists. And if these electricians coworkers are stocking Cat-5 to be installed in walls, that's all they should be stocking.

Cheers, Wayne

 

[hbiss]

Ahh ok Ill ook that up I don't have my code-book with me in the truck today.
So the transformer is a Hammond BE2F 16.5V 40VA so I presume it can put out 2.4 Amps continuously.
I am not sure at what amperage it impedance cuts it off.

It's not up to us to decide what class a power supply is. It should be stated on the label.

What does the label say on your transformer hmmm?

-Hal

 

[LarryFine]

I am unsure about hooking cat5 up to a doorbell transformer.

If you're concerned about current and voltage drop, you can always parallel pairs of conductors.

 

[jaggedben]

If you look at the jacket and spool or box label, data cable is listed as type CMP/CL2. "Communications multipurpose and Class 2."

You are free to use it for any CL2 application.

-Hal

Nah, I think you'll find lots of things. Just looked at two examples here in the shop and one says CMR and the other seems to have no listing.

Any Cat-5 that is installed in walls needs to meet the requirements of 725.135, so it definitely exists. And if these electricians coworkers are stocking Cat-5 to be installed in walls, that's all they should be stocking.

Cheers, Wayne

725.135 just says cable has to be 'listed' and then clarifies a whole bunch of stuff that's definitely permitted. Listed for what, exactly? I suspect that many data cables are listed for purposes that don't include being directly connected to 60hz transformer. But I don't really know. I'd say read the instructions but you often don't find any.

 

[gene6]

It's not up to us to decide what class a power supply is. It should be stated on the label.

What does the label say on your transformer hmmm?


-Hal

I was not talking about looking up the transformer rather code section. I thought Ben's posting of 725.144 is a reference to an ampacity table?
At 40VA 16.5 volts I think the short circuit current of ~2 Amps is in excess of a 23 or 24 AWG cat 5 cable.
Thanks everyone for your feedback so far.

 

[electrofelon]

Go with Cat5 and land it somewhere that the Internet servcie is going to available/accessible. Many people want video doorbells and if you have Cat5 you can get that done without batteries and without WiFi.

Are not most of these video doorbells wifi? IF you have a two conductor wire to give it power isnt that all you need? Do these have the option to hardwire with a cat5?

 

[letgomywago]

Are not most of these video doorbells wifi? IF you have a two conductor wire to give it power isnt that all you need? Do these have the option to hardwire with a cat5?

Most video DBs just need power from the transformer

 

[gene6]

Ok thanks everyone my apprentice found this link:

https://support.ring.com/hc/en-us/articles/360041807292-Selecting-the-Correct-Wire-Gauge-when-Wiring-a-Ring-Video-Doorbell-Pro

While we're not providing this brand of doorbell, it appears the mfr instructions say 18 or 16 AWG
Also she looked up a data sheet for Beldan cat5 and Honeywell 18/3 T-stat wire.
'doorbells' are an approved use for 18/3
and for cat5 its not an approved use unless its a "poe" system.
So my code reference to justify ordering 18/3 is 110.3.

 

[letgomywago]

New construction I use cheap cat 5e for Door bell and garage door openers. I use 18 8 for thermostat and 18 5 for ac and heat pumps even though they don't need all the wires it makes life easier and there's no jumping between colors that way.

 

[Sea Nile]

What does the label say on your transformer hmmm?

It says Made in China, of course.

But if you can run PoE then you should be able to run a doorbell transformer. Just make sure its pure copper and not CCA.

I have a PoE injector that outputs 48v.

 

[hbiss]

Nah, I think you'll find lots of things. Just looked at two examples here in the shop and one says CMR and the other seems to have no listing.

Did you happen to look at Table 725.154(A) Cable Substitutions? Any CM cable can be used as CL2. So, your CMR can be used as CL2 riser.

And if your cable has no listing, you can't use it within buildings anyway. Probably stranded patch cord cable from China.

I was not talking about looking up the transformer rather code section. I thought Ben's posting of 725.144 is a reference to an ampacity table?
At 40VA 16.5 volts I think the short circuit current of ~2 Amps is in excess of a 23 or 24 AWG cat 5 cable.
Thanks everyone for your feedback so far.

725.144 talks about the ampacity of the pins in a RJ-45 connector, not the 23 or 24AWG conductors.

Again, it's not up to us to determine the circuit class. You choose your wiring according to the label on the power source. It's as simple as that!

-Hal