I would like to install an ADXL335 accelerometer sensor that will be away from Arduino UNO about 15 metres
Is it ok if I use CAT5 cable ?
That sensor outputs fairly high impedance analog signals, the output
impedance is 32k or so.
I would use shielded cable really - just like for audio - better at protecting
sensitive signals. Multicore screened cables are commonly available.
If you stick with UTP then one pair for each signal (plus ground), one pair
for power (plus ground).
The ADXL335 suggests filter capacitors on each signal, for a long cable
run you want capacitors at the receiving end anyway to reduce EMI pickup,
so place the filter caps at the Arduino end if possible.
Hello MarkT
Thank you for your reply and suggestions
In fact I have a reel of CAT6 in my garage which I can use, and I will also use filter/decoupling capacitors as you suggested to reduce the electromagnetic interference. The twisted pair for each signal is also a good idea though I might experiment without it at first 
Signals should always be paired with grounds if using twisted pair. With a shielded
cable the wires share a grounded shield, but crosstalk can be more (matters at
higher frequencies more).