Low Voltage Mains

Should it be the New Standard?

Rob Bell

Issue 3, September 2017

In the age of logic-level electronics, USB-powered everything, does it still make sense for high voltage mains power to be the standard in buildings?

It’s been well over 100 years since electricity was first introduced to buildings, and high voltage AC distribution rapidly became the global standard (rightly so). However when this occurred, electricity usage was really focused on lighting, to replace oil lamps and such. Of course, it gradually moved to appliances too. Regardless of the original intention, there could never have been a prediction that low voltage appliances would become so common within a household. Even in the 1980s, computers were large and expensive, with the VCR often the most complicated piece of technology in the house.

High voltage mains wiring makes sense for power-hungry connections such as a refrigerator, air conditioner, kitchen and laundry appliances, and a few other things. But for the majority of appliances now found in a household, would low voltage wiring make more sense?

Consider how many appliances in your house are truly mains-powered: the WiFi router, the bedside lamp, the phone charger? All of these things are independently reducing mains voltage to 5-12V (usually) with their own plugpack transformers.

This trend is increasingly acknowledged with the availability of adapters and mains wall plates that provide mains power, as well as USB power in a standard fitting. The mains USB caters for the fact that in many households there’s a battle, but it’s not over the mains outlet so much, it’s now over an available USB outlet!


There are different considerations required for the lighting circuit in a building when compared to the power circuits. Lighting, even in an old-school incandescent scenario, typically draws far less power, and doesn’t have the drastic changes in load like a mains circuit has with large motors, heating elements, and other high-load systems. In a modern world of LED lighting however, the power consumption for lighting continues to fall, with the power of a conventional lightbulb now capable of illuminating every room an entire house!

The demands on the lighting installation also remain flexible, and are far less than for mains outlets. While the layout of a lounge room may change as furniture and fixtures are updated, the same is rarely true for lighting. For rental properties and home owners alike, the lighting fixtures are accepted as a permanent installation that are often only changed out of necessity or during renovations.

Consider for a moment, if your house lighting was wired with 12VDC from the meter box. You would have a safe, low voltage, accessible power source that you couldn’t really get into trouble with. You could wire in new lights yourself without requiring an electrician, and even for electricians doing the job, there is a marked improvement in workplace health and safety. You would have less EMF and heat generation in the roof cavity from all those lighting transformers, which are most likely already there, and plug-in LED globes would be cheaper (since a 12V driver is simpler and cheaper to produce than a mains driver).

Indeed for many devices around the house, you could use a similar 12V circuit to provide low voltage outlets. Plugpacks could be replaced with simple (or simpler) cables. You can have one highly efficient mains to 12V (or 5V, or both) converter in your mains box, which is distributed around the house (with its own 12V circuit breakers, of course). Even a standard computer converts the mains power to 12V and 5V rails; this would further be simplified if 12V power was readily available.


There’s a huge additional benefit of a 12V dominant system: renewables. As we push further to renewable energy, it’s increasingly common to generate or store wind or solar energy locally in batteries at 12VDC. By removing the need to invert this power from 12V back up to mains voltages, (which are often then converted back down again to actually power something), substantial efficiency can be gained which would otherwise be lost with the complicated electronics required to do so (especially when there’s no other benefit from the conversion).

Indeed, whenever possible many off-grid installations do away with mains power and focus on low voltage lighting and appliances. It’s safer, more energy efficient, and just makes sense.


There is little doubt that high voltage mains are the best option for refrigeration, electronic heating, pool pumps, and other devices with high power requirements. But outside of long range distribution and high consumption devices, a 12V system provides some huge benefits.

In reality, there is little stopping someone from doing this themselves, especially for low voltage lighting. Perhaps the biggest challenge is the lack of a DC connectivity standard. Even among common DC connectors you have 2.1mm, 2.5mm, and just about every other size between 1.0 and 5mm. Even with the dominant standard of a cigarette lighter/vehicle-powered 12V sockets, there are also Merit connectors, and the increasing popularity of Anderson connectors for their reliability and support of high current. Of course, there are many others, including PV connectors common in solar installations too.

One major benefit GPO mains connections have going for them is, they are relatively standard. Within most countries, fairly consistent standards exist. Sure, there are some worldwide variances, but at least that’s limited to about three types.

Will we see a new connection standard to support all low voltage devices? Arguably USB Type-C is attempting to be that standard with its ability to throughput much greater power than previous USB iterations; but there are very real limits to its capabilities for power. This is largely due to its design, primarily as a data connector and not as a power connector. In my own personal experience I’ve also struggled with some connectivity issues as the connector wears.

Are we simply destined for a world of endless adapters, converters and mismatched frustrations? Or will we see a new, low voltage standard reign supreme, ushering in new standards for efficiency and safety through buildings around the world? Only time will tell.