Cable sizing calculation

[An Buachaillín Bán]

Happy New Year all.

Quick question regarding cable sizing. I have a 25m run from DB to car charging unit. The 25m run will mean approx 8m is run in the attic, 6m is run clipped direct down and across a wall and the remaining 10-11m will be buried underground in a 2 inch duct to the car charging unit. My calculations tell me I require a 10sq cable. However, whenever I've seen other sparks install a 7kw car charging unit, it's usually a 6sq cable run. Granted the runs would be a bit shorter.

Any thoughts or tips on this please?

 

[buzzlightyear]

Quick question regarding cable sizing. I have a 25m run from DB to car charging unit. The 25m run will mean approx 8m is run in the attic, 6m is run clipped direct down and across a wall and the remaining 10-11m will be buried underground in a 2 inch duct to the car charging unit. My calculations tell me I require a 10sq cable.

and what cable will you use ?

 

[An Buachaillín Bán]

and what cable will you use ?

Apologies, SWA

 

[James]

If your calcs show 10mm then install 10mm
car will charge a little faster with a lower volt drop.

 

[James]

depending on de-rating factors, it may be possible to do the run in 4mm swa. assuming a 5% voltage drop.
do you want to share your calculations for a double check?

 

[An Buachaillín Bán]

depending on de-rating factors, it may be possible to do the run in 4mm swa. assuming a 5% voltage drop.
do you want to share your calculations for a double check?

To be honest James I use an app- Electrical Calculations. It auto calculates the cable size once you enter the specifics/parameters. Voltage, load, PF,
length of run, max volt drop, method of install, ambient temp, conductor, insulation etc. Not good practice I know to be putting my faith in an app for this.

230v, 7.4kw, 0.9 PF, 30m line run, 4% volt drop, I changed the method of install to buried directly in the ground, ground temp of 10° and it suggested a 6sq cable