DIY How to build an UV-C lamp for disinfecting viruses and bacteria

We’ve all been on a rush to stock up on disinfectants for our hands, for our floors, clothes – whatever it takes to keep us safe from this emerging coronavirus, COVID-19.

Everyone’s been telling us that soap and alcohol both do a great job at sanitizing surfaces and by all means do it as much as you can: wash your hands regularly, sanitize clothes and surfaces as they might have been in contact with possible contaminants, and this should at least keep the odds of getting us sick on the down low.

Shield yourself from coronavirus with this DIY UVC lamp

But what if you need to make sure that the fruit and vegetable you plan to eat or cook are safe and virus free? How about packages items that cannot get wet or soaked in alcohol – like a bag of flour for example?

There hasn’t been a lot of talk about the power of Ultraviolet light to kill germs (viruses and bacteria). It’s been used for a long while in hospitals (and even in the food industry) to sterilize surfaces, food production lines or even water and air.

Only recently there were some news about some UV-C robots (incredibly expensive) that disinfect hospital rooms and corridors with the simple principle: Exposure to a spectrum of light – invisible to the human eye – that can kill more than 99.9% of viruses and bacteria that’s exposed to. This is the power of UV-C, a 254 nm spectrum of light which is hazardous to the skin (and eyes) but if used properly can be of a great help at keeping surfaces virus free.

As a matter of fact, you can build yourself your own virus killing lamp by using just a few simple parts available online:

An UV-C lamp (here we used an OSRAM HNS L 24 Watt 2G11 Puritec Germicidal Ultraviolet Lamp)
An electronic ballast (here we used the OSRAM QT-ECO 1×18-24/220-240 L)
Electrical connector (2G11) and some wires

It really is that simple, and you also don’t need a bunch of tools to get this project done by yourself, at home.

You can do this in a (very) few simple steps:

Make sure to size correctly the lamp(s) with the ballast. See tentative compatibility chart here.
Figure out the wiring needed for the connections – this is the trickiest part – but if you’re like me and save some wires around the house from an old lamp you should be all set:

The 2G11 connector accepts solid wires between 0.5 and 1 mm2. If you have solid wires of this gauge, you’re all set. I didn’t so I had to use some crimp
pins. Once you prep your wire you just need to push it through the little holes of the 2G11 connector as they will fit in snuggly. Be aware that even though
the 2G11 connector has 6 holes, you will only use 4 of them, as the two outermost pairs are connected together. I’ve used the two outermost holes and the two innermost holes. Pay attention which wires go where, as you will need to connect them in order to the ballast
On one side of the ballast you would connect the 4 wires coming from the 2G11 connector – in the order specified on the ballast. Connecting the wires to this model QT-ECO 1×18-24 was easy, as you just need to strip off 8-9mm of wire coating and insert it through the designated connector while pushing
down on the connector with a screwdriver. Both stranded and solid wires work here. Just make sure to twist the stranded wires if you use this type of
cable
On the other end of the electronic ballast you just need to connect an electrical cable which will go right into the 220V wall socket. Like previously said, I’ve repurposed one from an old lamp that got broken.

Once you accomplish these very simple steps your lamp is ready to go. You will need to take some precautions (see below) and you may want to check a few tips on making the project easier and / or sturdier.

Precautions when using an UVC lamp

UV-C radiation is dangerous not just for viruses, but also for human eyes and skin:

Never look into the blue-violet light as it can severely irritate your eyes
Do not expose your skin to the UV light while you’re irradiating goods / surfaces
Try to turn on the light remotely (from another room) by either plugging it in outside the room currently being sanitized or by using some smart plug
After the light has been on for enough time (minutes, seconds even) you will notice some specific smell. It is good idea to ventilate the air in that room
Pay attention to any living beings around the lamp. UV-C light is known to break DNA chains so it could impact anything from pets to plants

Tips for a better project on building an UVC lamp

1. Try to expose as much of the glass tube as possible. UV-C radiation doesn’t really reflect off surfaces, so for a proper disinfection you will need a direct exposure from the lamp to the target surface
2. Use some tape so secure wiring in place
3. Ensure that the electrical connector is secured against unwanted tripping over. Making a loop and tying it in with plastic bands could be a good idea
4. Use a stable base. I used some plywood as it was easy to work with. You can just fix everything down to it with screws. We’re not aiming for something pretty here – but something that works. Remember – no one is supposed to look at it.
5. Try not touching the lamp too much. Also if it gets dusty, clean it with a cloth to make sure UV light is not being prevent from radiating.s

How does this UV-C to sanitize items?

UV light in the spectrum of 254 nm is a type of radiation with a wavelength lower than its UV-A and UV-B counterparts – which range from 280 to 400nm – and are responsible for sun tanning and sunburns.

UV-C radiation is also emitted by the sun, but the Earth’s atmosphere does a good job at filtering it out. Hence, viruses and bacteria are not immune to it, as it was never the case to develop a self-defense mechanic against it. However, with the use of specially designed lamps that boast a special type of glass which does not filter out this type of radiation, you can produce this kind of energy simply and efficiently to bombard any unwelcome and invisible bastards with it. Engineers are godsend, really.

Is UV-C light safe for humans and animals?

As long as you avoid contact with eyes and skin you should be good. One issue could be the residual smell, which is in part attributed to various airborne particles (like mites) that burn and emit small quantities of substances and in part to some (allegedly) emissions of ozone.

Even though most lamps claim they are ozone-free apparently this type of energy has the capability of breaking O2 molecules which could join back together and form ozone (which is not good if you breathe it). So it you ventilate the room and / or have an air purifier you should be fine.

How long should I expose my stuff to this light?

For cleaning rooms, there is a good rule of thumb:
– 1w of power for every cubic meter of air for a time between 10 and 30 minutes should be enough to sanitize.

As you’ve probably guessed by now, the efficiency of this exposure of a function of time and distance. Aka how long are you exposing surfaces (walls, food items, boxes delivered by a carrier) and how far away from the lamp they sit.

Although there’s no magic formula, I try to keep items for about 10 minutes in the range of one meter or less to the lamp’s tube.

Please understand that only the surface that is in direct contact (read line-of-sight) with the lamp gets sanitized, so with only one lamp you will need to move things around and re-expose to complete the sanitization.

Can I buy an UV-C lamp already made?

Of course you can get an UVC lamp that is already assembled, I took the DIY route as the delivery time of all the lamps was incredibly high due to the high demand and transportation restrictions generated by the coronavirus pandemic.

Here’s a selection of some good UVC lamps that you can get on Amazon.com if you live in the US, or on Amazon.co.uk if you’re based in the UK.