SWA for PV DC

[mac1]

Hi,

I know there has been questions about this already but I wanted a definitive answer to the question - "Is standard SWA ok to use for DC runs from the array to inverter " ?

Thanks

Mac1

 

[BruceB]

It depends on the voltage you have designed your system for (ie how many panels of what type in each string).
Standard BS5467 SWA is 600V/1000V. I have not delved into the standard, but I would have thought those voltages are either nominal / between cores figures or rms / peak figures. Whichever they are, they will be high enough for many or most domestic installations.

Regards
Bruce

 

[mac1]

Hi Bruce,
Thanks for that it is not going to be more than 1000v dc for sure.

 

[BruceB]

You also have to overspec the dc cable slightly - see page 16 of the DTI Guide
Voc(stc) x M x 1.15

 

[mac1]

Hi Bruce,
Yes I understand, thanks I will factor that in. But it is fine to use 2 core SWA for DC.

 

[daytona600]

real pv cable ie 4mm2 is rated at 55amps 1.8kvdc
if required pv cable/busbar for string/central inverters in stock to over 5000amps

 

[mac1]

Hi I am not sure I understand what you are saying, I am looking for a robust external cable I can use for DC to go from the array to the inverter which is about 20m away. I just wanted to know if SWA is ok to use. 4mm PV cable offers very little mechanical protection so is not suitable.

Thanks

 

[JD6400]

Can you not trunk it ?

 

[daytona600]

could always fit inside amoured conduit if protection is required

 

[hduz5]

Where necessary, the company I work for has run many DC runs in two core 4mm swa.

 

[BruceB]

I agree with hduz5. Talk of armoured conduit is overcomplicating a simple issue. Just make sure the voltage is within limits and use SWA.
Regards
Bruce

 

[edexlab]

could always fit inside amoured conduit if protection is required

This is correct but you have to earth any steel conduit which then gives you the problem of where this is referenced to ,obviously it's of no use to earth it to the MET
you probably could leave the swa armour unearthed/floating ie just relying on the mechanical protection but i think you would have to earth the conduit as it would be an exposed conductive part, be interested to hear what others think