Cat5 cable power drop?

fleetz

Active Member
I am installing a Viking intercom 100' from the control unit and the door box (C-1000B and W-3000) and want to calculate the voltage drop over a run of Cat5e cable (solid conductor).

Is there a neat calculator that enables you to put in an input voltage with nominal current and have an estimated voltage over a nominated distance of Cat5e cable?

Thanks,

Fleetz
 
Thanks guys exactly what I am after.

I take it that to calculate the combined AWG of two pararlelled cables you add the two diameters together e.g 2 X 24AWG would be 2 X .0201=.0402 which would be very close to 18AWG (.0403) ??

Cheers,

Fleetz



'
 
fleetz said:
Thanks guys exactly what I am after.

I take it that to calculate the combined AWG of two pararlelled cables you add the two diameters together e.g 2 X 24AWG would be 2 X .0201=.0402 which would be very close to 18AWG (.0403) ?? 

Cheers,

Fleetz
AWG sizing is related to the cross sectional area, so I would think you would want to take "pi" *r*r and multiply that by two.

So calculate the area, multiply by two, then solve for diameter from that value and you get a number more like 0.0284 (if I did my math correctly).

Let's see what others say. :)
 
I think that BraveSirRobbin is correct in that you need to use the cross sectional area.

I used this chart here for evaluation.

AWG 24 = 0.20 mm2 x 2 = 0.40 mm2

AWG 21 = 0.41 mm2

So paralelled AWG24 would closely match AWG 21
 
Remember to double the distance.

When calculating voltage drop down a cable, you need to add the drop both TO and FROM the load. Those calculators may do that for you.

Also, to avoid doing cross-section calculations, I just use the manufacturer's resistance specification.
 
Thanks Guys

"Pi" R squared jeez that digging up maths I have not used in 35 years :)

Nice to know somethings don't change only your abliity to recall them.

Appreciate your collective input and the math refresher....it all makes sense now!

Regards,

Fleetz
 
I'm also looking at running power over Cat5. I have one of those Cheaper RFID Receivers that I need to mount in my garage. It uses serial, but I found out that I can get 2 RS485 adapters (one for each end) to extend the cable to the length I need (~100ft). I used the calculator, and it came out to be 11.99767 V if I use a 12V Transformer, as the receiver draws 4mA. Does that sound right? Are there any issues with running the power in the same cable as the data?
 
Back
Top