One power supply with multiple devices

Hi,

I need to supply power to some solenoid valves and vacuum pumps. All are 12V, there will be around 12 of them but not turned on at the same time, the maximum current draw would be around 3A. I am thinking of getting this 5A supply: https://www.amazon.co.uk/BW-Power-Supply-Splitter-Cable/dp/B00C96U6WK?th=1.
Now my question is: Is it safe to use the 8-way splitter to connect such devices? I would just cut the cables and attach them to the valves, and control everything with transistors. Is each of the cables rated for 5A?
If I have pairs of valves, where the two will never be open at the same time, can I power them with the same cable? Is there anything I need to watch out for?

To me it makes sense, but I'm a big electronics noob. Thanks for any advice.

Peter

No bother anymore, feel free to delete if possible