What conduit for 24 volt underground solar cable?

Question

I need to run 24VDC about 30m to the back shed to power some water pumps and lights. I bought a roll of DETA 100m 6mm² TPS Solar Cable Twin Core from Bunnings and wasn't sure if I can directly bury this under the gravel and grass to the back shed about 30cm deep or should I get some orange 32mm conduit with some gray conduit towards the surface for better looks.

Nailbag · Answer

Morning @quacka

For the sake of long term reliability vs the relatively cheap cost/m of using conduit, I would reconsider running the cable in conduit as that particular cable is not intended to be run in-ground.

Nailbag

quacka · Answer

Thanks all for your responses.

To add more clarity, I run various small hydroponic NFT systems and would like to use these pumps to pump the nutrient from the reservoir to the top channel.

https://amzn.asia/d/048gUPXt

I think there is also a 12v variant of the pump and would be ok for my needs. The only reason I am planning to order the 24v variant is so there is less a voltage drop over the distance. From what I am reading this would be minimum and was hoping these 24v pumps voltage range would be suitable.

I am planning to use a 24V adapter from the existing power point outside my house to outside of the back shed where the hydroponics systems are. I don't want to run 240v back there as I will need to dig 60cm deep and get a sparky to wire it up which would be way outside my budget for a small gardening hobby :) I also recently laid out new instant turf and don't want to dig it up too deep and ruin it, this is why I am considering using the 24v route.

I also have a spare ArkPak 730 | ARK battery box and could use this for battery backup if I want to. To install this, I would need to hook it up to a buck converter to step down the voltage to 12v to charge the box. The ArkPak has a limited DC input of about 5amp @12v which would not be sufficient to run the 5 pumps as it is rated to consume 22w each. Going this part would be best as it will provide battery backup for the pump if there is ever a power outage. I might hook it up anyway via a junction box just in case I need it for another purpose in the future.

I was thinking of just running it without conduit as I don't mind 24v cables being cut accidently as it is low voltage like lights. The likelihood of my digging the grass up again would be very rare as I just laid it down. I was just worrying the shielding of this cable won't last with the constant moisture.

Dave-1 · Answer

Good Evening @quacka

I have the same thoughts as @MikeTNZ about voltage drop over that distance. 30M is a fair hike and I think you will run into issues.

Orange conduit is for underground work, I would go that route for sure. If you are running the pumps from solar panels, is it possible to mount the solar panels nearer the pump? If not then 240V installed correctly and use a transformer to step it down at your shed would be my recomendation.

6mm cable make work voltage drop wise but I think issues will develop, You cannot install TPS straight in the garden :) My Grandfather did lol and as a teenager I was digging up extentison style cords for the pond pump and backyard lighting that he had burried direct in the earth (he had the electricians at the steelworks horrified when they found out where his questions were leading to :) )

Oh and a stringline installed as you are installing conduit makes life a LOT easier to pull in cable. When I installed lights in my front yard I installed stringlines in all my conduits (Yep I am a sparky :) )

Dave