How much Amp can I transfer over Cat-5 with 12V DC with all 4 Pairs
- Thread starter shaurya
- Start date
Sacedog
Active Member
Do you not have an option to pull a 2-pair cable for power?
Hello Sacedog,
Thanks for your response.
Yes & No for the option to pull 2 pair cable. I prewired my house with Cat-5 for the places I wanted to have touchscreens. At some locations I can drop another 2-pair cable (eg Upstairs), however at someplaces I can't (eg downstairs).
Regards,
Shaurya
Thanks for your response.
Yes & No for the option to pull 2 pair cable. I prewired my house with Cat-5 for the places I wanted to have touchscreens. At some locations I can drop another 2-pair cable (eg Upstairs), however at someplaces I can't (eg downstairs).
Regards,
Shaurya
rocco
Active Member
Hi Shaurya,
How long is the run? What gauge is the wire? (most likely 24 AWG, but could be 22 or 26). What is the minimum voltage that the touchscreen will accept. And finally, does it really draw 4 amps?
Given the gauge of the wire, the length and the current, we can calculate the voltage drop. We then need to decide if it is significant to the touchscreen.
Sacedog
Active Member
This calculator can help to determin how much you will be able to transmit over 2 pair cables, however, this wont really work for Cat5. I'm not sure how you would figure out the gague of the wire when using multiple wires from teh 8 in a Cat5. You would basically need to figure out what guage is equal to 4 26ga Cat5 wires.
http://www.currentsolutions.com/knowledge/vdrop.htm
A suggestion, try it on a bench. Measure the voltage at the end of a couple hundred feet of Cat5 and see how much drop you get. Leave it plugged in for a while to see if the Cat5 cable gets warm at all. If it does, you should probably not be using it. I'm no sparky though, so you should probably consult someone who has experience with LV power distribution.
http://www.currentsolutions.com/knowledge/vdrop.htm
A suggestion, try it on a bench. Measure the voltage at the end of a couple hundred feet of Cat5 and see how much drop you get. Leave it plugged in for a while to see if the Cat5 cable gets warm at all. If it does, you should probably not be using it. I'm no sparky though, so you should probably consult someone who has experience with LV power distribution.
rocco
Active Member
That part is easy.
Putting two wires of the same gauge together is equal to one wire that is three gauges lower. Two 24-awg wires is equal to one 21-awg wire, and four 24-awg wires would be equal to one 18-awg wire. Four 26-awg wires would be equal to one 20-awg wire.
Guy Lavoie
Active Member
I'd say that 4 amps is ok, as long as the cable length is not something out of the ordinary. If you can keep it to 60 feet or less, I don't see a problem. If its a couple of hundred feet, then you should check the voltage drop as others have suggested.
Sacedog
Active Member
Very cool to know. Thanks for the info Rocco!
drozwood90
Senior Member
I believe if you use POE, you can get 12-16W (maybe more??).
Although, that is because POE runs at 40-50 Volts (so you need POE injectors and receptors to pull the power out of the lines for you).
--Dan
Hello All,
Just wanted to update cocooners that I did a bench test as suggested and I believe 4Amps can be supplied over Cat-5's 4 pair.
Supplied 12v dc power to 100 foot cat5 and kept the monitor on for 4 hrs. Cat-5 didn't get hot..may be warm (very mild). So it apprears that I can tranfer enough wattage over cat5 at 12v DC.
Please feel free to update the thread with any further info.
Regards,
Shaurya
Just wanted to update cocooners that I did a bench test as suggested and I believe 4Amps can be supplied over Cat-5's 4 pair.
Supplied 12v dc power to 100 foot cat5 and kept the monitor on for 4 hrs. Cat-5 didn't get hot..may be warm (very mild). So it apprears that I can tranfer enough wattage over cat5 at 12v DC.
Please feel free to update the thread with any further info.
Regards,
Shaurya
Well since nobody else has posted this... Don't do it this way.
How will you know if one of the leads breaks?
How does the calculation work with one 3 pairs?
You would have to use a 4+ amp fuse, thats quite a bit of 12v power.
You might see if you can't just do wall warts wherever possible first, the interior walls should be hollow. If you can find on with a wall outlet below or on the opposite side you can do this with ease.
How will you know if one of the leads breaks?
How does the calculation work with one 3 pairs?
You would have to use a 4+ amp fuse, thats quite a bit of 12v power.
You might see if you can't just do wall warts wherever possible first, the interior walls should be hollow. If you can find on with a wall outlet below or on the opposite side you can do this with ease.
BraveSirRobbin
Moderator
Basically the cross sectional area of the wire determines how much current it is capable of carrying. So all one has to do is to determine the area of one of the wires they want to gang (pie r**2), then multiply this number times the number of wires you want to "gang", then look up to see what gauge wire this new cross sectional area represents, then use that gauge's current carrying specifications.
huggy59
Active Member
I have to agree with CollinR - I believe failure mode here could cause a fire. Say a mouse chewed one of the cables and broke one or two wires (right, Dan?). Now you have 4 amps trying to pass over two pair of small LV wires. Try testing that 4 amps over 40-60-100 feet on two pair and see what happens to your Cat5... I bet it melts!
At the VERY least, you'd have to run a single fuse (1 Amp?) for each pair to limit total in EACH pair. Then if one pair is compromised, the other fuses should blow when the load ramps up on them. In cases where multiple conductors should be disconnected if a single conductor is compromised, one usually uses a circuit breaker with a mechanical trip on ALL conductors (hence the typical 220VAC breaker for your dryer having a bar across both breakers - if one goes, it takes the other with it). I'm not sure how you'd do that in this case.
Then there's the insurance claim issues... I recommend you do it with the right wiring according to code and then not have to worry about it. So what if you have to make some holes in some sheetrock.
At the VERY least, you'd have to run a single fuse (1 Amp?) for each pair to limit total in EACH pair. Then if one pair is compromised, the other fuses should blow when the load ramps up on them. In cases where multiple conductors should be disconnected if a single conductor is compromised, one usually uses a circuit breaker with a mechanical trip on ALL conductors (hence the typical 220VAC breaker for your dryer having a bar across both breakers - if one goes, it takes the other with it). I'm not sure how you'd do that in this case.
Then there's the insurance claim issues... I recommend you do it with the right wiring according to code and then not have to worry about it. So what if you have to make some holes in some sheetrock.
As I have been reprimanded by many, I have decided not to use Cat5 for the power (12VDC, 4A). I would like help in deciding the right guage wire. I have 16/4 and 16/2 (both used for speaker wiring) at the moment. Which one is good for the use. I can buy something else as well if required. Please advise.
Regards,
Shaurya
Regards,
Shaurya
Sacedog
Active Member
It depends how far you need to run the wire, and what voltage will be acceptable at the tablet. When you run LV over distances, there is always a drop in the voltage from the power supply to the remotey powered item (in this case a touchscreen).
With 16GA wire, pushing 12V, 4A, over 50 feet, the voltage at the touchscreen will be 11.2V. With 14GA wire, it would be 11.5V. With 12GA wire, it would be 11.68V. Before I ran the wire, I would hook up your touchscreen to the power supply, using the same length of wire that you plan to use in the house for powering the unit. That way, you can make sure it works first.
As for the question, will speaker cabling work for that application...I'm not sure. I would check your local codes to see if they have any requirements for LV wiring.
