Need advice from the power wise members.
My question relates to current and wiring capacity.
I have a PC based I/O controller and am going to use it to control a few external relays, that in turn will control different appliances around my property. The writing of the software should be reasonably simple with a touch screen interface to show status / override, etc.
I will probably be using either a 5V or 12V DC supply ( around 3A ).
The distance to the external relays, ranges from 10 to 40 meters. The external relay is rated at 10mA - I assume this is the amount of power that it is going to pull from the supply when fed power, and this is the amount of power that the wiring needs to be capable of carrying.
If this is the case, and the fact that the supply transformer (at 3A) is irrelevant, can I use my existing wiring for my alarm system to carry the power to the relay ? The existing wiring is already in the right places, is 12 core standard alarm system cable, and I have at least 4 unused strands.
All advice appreciated.