CB and Wire gauge question

[Denzelm]

Good Day,

Please can someone advise on a question i have about CB and Cable size.

Im taking a power feed from my main switch (2P 63Amp) to my 5KwH inverter AC input . The inverter AC input cable requirement is 4mm however I went 6mm (47Amp rating).

My question :

since the main switch (2p 63Amp) has 16mm cable , can I take a feed from the main switch (2p 63Amp) using 16mm cable to feed a 2P 40Amp breaker and connect my 6mm AC Inverter Input cable? This would mean my inverter AC input 6mm cable will remain safe from any over current .


Regards
Denzel

[AndyD]

Generally a wire or cable should be supplied by an appropriate sized upstream circuit breaker ie if you connect to a 60A breaker it should be a 16mm wire/cable or larger. Using the main breaker as the sole means to protect a final circuit is bad practice, the circuit should have it's own circuit breaker.