4mm or 6mm for 9m cable from inverter to CU

[and]

Installers are here, they want to use 4mm for the 9m run of AC cable, I thought the general opinion was that 6mm was better, ie less of a power loss.
Quick reply needed!
Thanks!

 

[and]

Come on! ... a bit of speculation will do!

 

[bris]

4mm for a 9m run is enough.

 

[SolarCity]

What inverter are they using?

 

[and]

Power One 3600 (the indoor one)
16x REC 245PE

 

[danesol]

From what I have read.... A 3kw system must have a minimum size of 4mm cable to a maximum length of 23m long, 6mm to 32 metres and after that 10mm.

"Refer to the 17th edition regs book, chapter 54 covers it.
To add a new circuit for PV requires Part p and full electrical certificate which includes uprating the earth . regulation 131.8 page 16 covers the issue."

 

[SolarCity]

As others have said, 4mm is fine. SB4000TL would have needed 6mm (although I doubt that it would make any difference anyway over that kind of length.

 

[and]

Big THANKS!
Give me confidence to have a consensus of opinion!

 

[and]

That should be "Gives" no "Give"

 

[and]

Well, the 4mm cable is in, I upgraded my gas/water mains earth to 10mm, the rails are on, panels going up tomorrow! ...

 

[poheZ]

have you worked out the volt drop on a 2.5mm cable?

 

[and]

Don't quite understand why work out the volt drop on a 2.5mm cable? ... would like to understand ..

Not being an electrician I'm not really up on volt drop calcs ... but that was the essence of why I asked which is more suitable: 4mm or 6mm.

 

[poheZ]

well, why do you think 'power loss' will occur?

How much 'power loss' will occur if any?

 

[and]

Power loss due to cable heating up, the hotter it gets the more reistance which makes it hotter, etc.

How much power loss will occur? Don't know!

I assume the 4mm cable coming off of the Power One 3600 putting out a max of 16A will get no hotter and offer no more resistance than a 6mm cable. A 2.5mm cable on the other hand, I assume, would indeed warm up ... ????