Pool, your question suggests you need to learn the trade.
Nice!
62-108(1)(b) and 62-114(4). To summarize, The ampacity of the wire must be greater than the load and at least 1/3 the rating of the overcurrent device; and, the smaller wire must not be more than 7.5 meters long. Or, it must have an ampacity not less than the load and at least 80% of the overcurrent device; in which case the length isn't limited.
The code specifically allows it.
