24V power supply
In a direct electrical current (DC) the current travels in just one direction, from positive to negative. Just to make things more interesting the electrons that make up the current actually travel from negative to positive. In alternating current (AC) the electrons shuttle forward and back, perhaps 50 times per second.
There are some advantages to a 24V DC electricity supply.
The common belief is that more than 50V is needed to produce a sufficiently large current in the human body to cause electrocution, so 24V should be safe; especially when compared with the 230V AC that is the usual household supply in New Zealand and Australia.
If electricity is produced by solar panels or wind generators it will probably be 24V. Another advantage is that devices that run on 24V DC, such as laptop computers, don’t need a transformer and rectifier between them and the 24V power supply. It is said that a 24V supply doesn’t need to be installed by a registered electrician, however this is often not the case. There are disadvantages to a 24V DC supply.
It may not be as safe as it seems. Overseas there have been some fatalities caused by low-voltage electricity supplies. According to the electrical regulations, in most situations, for instance when connecting to solar panels, a registered tradesperson is needed. Arcing causes more problems for DC than it does for AC. ‘Arcing’ is when the electrons travel short distances through the air instead of staying in the wire — as seen in a petrol engine’s spark plugs. The greater the voltage, the greater distance the arcing can cross. Arcing is especially dangerous in a building’s wiring, as it causes heat that can result in a fire. The usual cause of the arcing is a loose connection or a small break in the wiring that the electrons can jump across. Special fuses are also needed in a 24V circuit. Voltage drop over longish wires is more of a problem at low voltages than at higher ones.
If you are installing a 24V DC electricity supply, professional advice is absolutely essential. You are making a big mistake if your sole reason for wanting a 24V system is avoiding the use of a registered electrician.
For more on creating a DC power supply see this article on The Shed website: the-shed.nz/home/2019/7/8/ acdc-converting-simply.