24 V or 48 V? Choosing a System Voltage

Twenty-four volts remains the default for industrial control, and for good reasons: the components are everywhere, and the voltage is comfortably within safe extra-low-voltage limits. As systems get larger, though, 48 V starts to look attractive.

Why the higher rail wins on distribution

For the same delivered power, doubling the voltage halves the current. Resistive loss in a cable goes with the square of current, so it falls to a quarter. Voltage drop along the run halves. In practice that means thinner cable, longer runs, or both — which is why 48 V is standard in telecoms and increasingly common in larger machines and lighting installations.

Where 24 V still makes sense

• Component availability. Sensors, valves, relays and PLC I/O are overwhelmingly 24 V.
• Short runs, modest power. If the cable loss is already negligible, the higher voltage buys you nothing.
• Familiarity. Maintenance staff expect it, and a mixed-voltage panel invites mistakes.

A practical compromise

Many designs now distribute at 48 V and convert locally to 24 V, 12 V or 5 V with isolated DC-DC converters at each subassembly. You get the cabling benefit without abandoning the 24 V component ecosystem, and local conversion keeps a fault on one branch from pulling down the rest.

Note that both voltages sit below the 60 V DC threshold generally treated as safe extra-low voltage, so the safety approach does not change — but always confirm against the standard that applies to your equipment.

See our DC-DC ranges for local conversion product options or contact us to discuss your requirements.