Thanks for pointing that out, Dave
My specks are for AWG.
Trev

Hi Nick
I feel I must point out that the USA and Canada use the AWG imperial system whereas the UK changed to a metric system. SWG is still in common use in the UK but is really thy British Standard Wire Gauge which is metric.
The AWG and SWG are different as are the ratings.
The general information given is correct but please be aware of this difference.
Many suppliers will give the current rating for electrical wire they sell so you can ensure you have the correct wire for your purpose.
dave976

All depends on the amps drawn.
Rule of thumb
14 GA -15 amps
12 GA - 20 Amps
10 GA - 30 Amps
Although for short runs of wire 12GA should suffice for most motors.
I like silicon insulated wire. much more flexible and durable.
Trev

Hi, for all my R/C builds, I use 12SWG for the primary wiring from Batteries to Fuse to ESC, and most times keep with 12 ga. to the motor, unless running 380 size motors or if geared.
I will then use no less than 14 SWG to the motor(s).
Always better to build overkill, than risk undersized wiring and connectors.

Nick,
There are two answers to your question, yes and no. A lot depends upon the capacity rating of the ESC and the current draw of the motor under load. Ideally, the ESC should be over capacity. It should be able to handle any current draw from the motor if the motor were to stall, ie, wrap in weeds, run into a rock, or if you were to lock the shaft, ect. The ESC should also be protected by a fusable link to protect it and the motor.
Back to your question, if your ESC has a capacity of say 40 amps, and your motor draws about ten amps at stall, then yes you could use smaller wire. If your motor draw were say 25 amps, then I, personally, would use the same size wire as the ESC. Manufacturers are notorious for rating ESC's according to their standards, not a universal one. Better to be safe.
Lastly, wire size is not the only factor in a wire's capacity. The number and size of the conductors that make up the wire are critical to it's capacity.
I you err on the safe side you will be far less likely to have problems in the future.
Cheers

The simple answer is the wire gauge needs to be capable of carrying the max current the circuit will draw. Good practice is then to protect the wire by using a fuse that blows below this max.
Receiver circuits normally only draw one or two amps whereas motors/ESCs can draw considerably more from say 5amp up.
Your ESC will have a max current rating and the 14 SWG wire is to meet that max. If you motor is of a lower power rating then yes you can use a smaller size but normal practice would be to use an SWG capable of carrying double the max current the motor can draw. You would use a fuse of a lesser rating to protect this thinner wire.
dave976