3D Printing Fire Guide – Detection, Protection & Prevention

3D Printers are being used in homes more and more every year, and naturally, people wonder whether they can cause fires. I decided to put together a guide on 3D printers and fires, as well as how to detect, protect and prevent them.

How Often Do 3D Printers Catch Fire?

It’s rare for a 3D printer to catch on fire, especially if it has the right firmware safety features and is assembled properly. Millions of 3D printers are being operated, but you very rarely hear about fires starting, but they have happened in some cases. It’s more likely to happen with unreliable brands.

Some people choose to pause their 3D prints if they are going out to reduce the chances of anything bad happening while they are gone.

You can compare the chances of your 3D printer catching fire to an appliance like an oven or stove in your kitchen. Heating elements in products like a water heater or dishwasher would be a larger fire hazard than a 3D printer.

As long as you take the necessary precautions, there shouldn’t be a cause for a fire outbreak. I’ll explain more details further in this article.

Reports have shown that most of the printers that do go up in flames are actually low-quality, poorly assembled 3D printers with bad quality control. One example in the past was the Anet A8, having a reputation for causing fires in a few cases.

One user stated that the Anet A8 was a real menace for 3D print enthusiasts due to them cutting too many corners in manufacturing.

The Anet 3D printer was said to lack some of the basic safety features present on other printers. He also stated that in a year alone, every 3D printer incident (4 or 5) was an Anet A8.

Another user stated that there were several fire reports on the Anet A8 and A6 3D printers.

He said the main cause of these fire accidents was that the thermistors which measure temperature were held in by adhesives rather than screws that would eventually detach from all the movement and high temperatures.

Even a reliable brand like Prusa doesn’t completely eliminate the risk. A user said he knew of one Prusa machine that reportedly burned, though it was thought to have been because it was a kit that was assembled improperly.

Here are some factors that can influence 3D printers catching fire:

Quality of the 3D printer manufacturing
Electrical wiring and connections
Good safety practices

Best 3D Printer Fire Detection

Fire/smoke alarm systems
Real-time monitoring devices

Fire/Smoke Alarm Systems

In terms of 3D printer fire detection, one of the key ways to do this is to install a smoke and fire detector near your 3D printer. This is a necessary step especially when you want to run your 3D printer for long periods of time or overnight.

When your 3D printer is in a basement or workshop area where you don’t have the easiest access, you’ll be leaving it unattended for the most part. You definitely want a smoke detector near there so you’ll be alerted in the rare chance that something does go wrong.

One user shared an experience with a fire alarm system he installed around his home. He mentioned that the fire alarm system alerted him to a fire from the room where his 3D printers were situated.

When he got there, the flames were about 6-8 inches tall and were easily extinguished with a fire extinguisher. If he didn’t have the alarm, it could have gotten a lot worse. It allows you to quickly react to a very dangerous situation.

You can even add extra safety by using a smart smoke detector like a Nest Protect and use an IFTT (If This Then That) command with smart outlets that kills power to the 3D printer if the smoke detector goes off.

Something like the First Alert Z-Wave Smoke Detector from Amazon should also work well. One reviewer said it can work with SmartThings to give you alerts and text messages, along with the option to shut down power or even call emergency services.

They mentioned using a HUSB1 controller with a Z-Wave network, then having one set up inside a 3D printer enclosure and an automation using NodeRed to kill power to the 3D printer if smoke is detected.

Real-Time Monitoring Devices

It is not always feasible to always be around your 3D printer when it is printing. To counter this, you can make use of real-time monitoring devices like a camera along with the Spaghetti Detective (now known as Obico).

This helps to check in on your print from anywhere and even tweak various settings as long as you have an internet connection and a device.

While you should never leave your unattended, Spaghetti Detective uses AI to ensure your safety by making sure your print is going according to plan. Once it notices the print is going sideways, it alerts you immediately or can pause the print automatically.

The Spaghetti Detective also has free and paid services. The free version has some restrictions on the features it offers. You may be able to counteract this by building your own server that can host the webfeed from the Spaghetti Detective.

Here’s a video review of the Spaghetti Detective.

One user said he usually sets up a Zoom call when he wants to go out so that he can monitor his print progress, but you can’t control the 3D printer using this method.

Best 3D Printer Fire Protection

The following are the basic ways to help protect yourself and your property in an event of a 3D printer fire outbreak.

Fire extinguishers
Automatic sprinklers and fire extinguisher balls
3D printer enclosures

Fire Extinguishers

As mentioned previously, one user put out a 3D printer fire using a fire extinguisher. I’d highly recommend getting yourself one that’s accessible near the 3D printer. In the rare situation that a fire occurs, this can make a very significant difference in the outcome.

He even had 2,000 hours of 3D printing experience but still didn’t expect this to happen. Rather than use a fire extinguisher with water, you should try to get a powder one since water doesn’t mix with electric. The user said he has portable fire extinguishers placed beside his 3D printer.

You can go with something like the First Alert Home1 Rechargeable Fire Extinguisher from Amazon. It’s made from a durable all-metal construction with a commercial-grade metal valve and trigger.

This is a multipurpose fire extinguisher that fights wood, paper, trash, plastic, oil and electrical-equipment fires. It can be recharged by a professional after use so it can be reused.

Automatic Sprinklers and Fire Extinguisher Balls

You can also get automatic sprinklers that are triggered by the smoke/fire alarm system beside your 3D printers. Once the alarm goes off, the sprinklers engage immediately and cut out the fire automatically.

One user said he has a print farm in a room with active sprinklers which is good for safety and peace of mind. This Fire Sprinkler Head Pendant Spray from Amazon looks good, with a few positive reviews.

Also, you can make use of self-activating fire extinguisher balls that you place above your 3D printer. They are fire-activated after 2-3 seconds and release a powder substance to quench the fire, though there’s not much stock of them on Amazon at time of writing.

A user installed one of these balls mounted directly above his enclosure, which also has a foil lining to offer a little bit of fire protection. If the fire burns through the enclosure, the ball would quickly activate.

Self-activating fireballs work effectively, especially for electrical fires. They can be messy due to the powder, but a small cost for extinguishing a fire.

I’d recommend also getting a Large Fire Extinguisher Blanket as another method of stopping a fire.

3D Printer Enclosures

Using an enclosure is a great method for preventing a fire. Some enclosures are better than others for preventing fires, while some might actually make things worse.

You definitely don’t want to use an enclosure with foamcore, styrofoam or a cardboard enclosure, along with a large fan that can feed the fire.

One ideal enclosure that a user made were from custom shelves for their 3D printer with a concrete tile backer board glued to the shelf above it with a fireproof caulking.

An airtight metal enclosure would be great for preventing fires from spreading since it cuts the flow of oxygen, or even a flame-resistant wooden enclosure by painting it with a flame-resistant polyurethane.

One user mentioned using concrete wood to make it fireproof and another, concrete board.

A simple enclosure you can get from Amazon is the Creality Fireproof & Dustproof Enclosure, though I’m not sure what level of fireproof they claim for this enclosure.

It has a fire retardant coating so it can help to reduce the fire from spreading, and should melt rather than burn.

Best 3D Printer Fire Prevention

Check & enable thermal runaway protection
Tighten up loose connections
Use a high quality board
Change out tinned wire inputs
Use strain relief on wires

Check & Enable Thermal Runaway Protection

Thermal runaway is a firmware feature that helps to stop your printer when it overheats. Every 3D printer should have this feature installed, though there are reports that some 3D printer manufacturers are not properly enabling them.

In recent times, they have gotten better at doing this after much backlash from the 3D printing community. It’s a good idea to check whether your 3D printer actually has it enabled.

These heating issues are usually caused by loose connections in the 3D printer, especially with the thermistor’s connectors. For example, when your heater continues to heat your thermistor does not detect it, and only senses room temperature, thermal runaway cuts off the heater’s power.

Also, if your thermistor shorts itself, a high-temperature reading is detected by the printer and immediately thermal runaway engages and power is cut from the 3D printer.

Some printers do not have this feature loaded in the printer’s firmware. Once you detect this you would need to update the Marlin firmware on your printer.

This feature is usually activated when one of the following situations occurs:

When the thermistor gets disconnected from the hotend
When there is a short circuit in the thermistor.
A wire break in the cables or the connectors.

This video shows how to test your current Marlin safety features, check them, and update them.

Tighten up Loose Connections

A good prevention method for 3D printer fires is to check your wiring connections and make sure they are properly secure and tight. 3D printers that have loose connections can burn and cause charring on the wires, and can even lead to a fire in the worst cases.

When your thermistor falls out the hotend, the 3D printer can continue to heat up since it only senses an ambient temperature and not the hotend temperature.

A 3D printer with the proper software protections should switch off since it wouldn’t record any change in the temperature of the 3D printer, but some cheaper 3D printers might not have this and continue heating up.

Use a High Quality Board

In order to prevent fires from your 3D printer, it’s a good idea to make sure you have a high quality board. When you have a cheaper 3D printer with a low quality board, they can have a high resistance even in normal operating working conditions.

In simpler terms, they generate a lot of heat even under normal working conditions. Yet, they are still rated to have the capacity to generate even more power for heating applications. This can lead to the heat generated rising exponentially and consequently lead to a fire.

You can check out this video for more information on this subject.

Another thing to keep in mind is the 3D printer’s MOSFET. These are a type of transistor used to switch a heater on or off when they reach the preset maximum temperatures.

In situations where they fail, they are unable to regulate the heaters attached to them.

One user who had a CR-10S 3D printer said their heated bed MOSFET overheated and failed, though he luckily realized before anything caught fire. He decided to design a safer MOSFET by integrating a watchdog that powers it off if the main MOSFET shorts and fails.

It’s possible for the MOSFET that controls your 3D printer’s heater to be stuck in the ON (conducting) state, meaning the firmware won’t be able to turn the heater off.

Most 3D printers have just single failure point with their MOSFET. One user described that in OctoPrint or Klipper, you can have a Raspberry Pi control your power supply. If there are any failures on the board, the Pi can cut power.

You can also have a manual way of cutting power like an emergency stop button, or reasonably pull the plug in an emergency situation.

Ideally, you want to have a decent quality board that detects shorts, along with a good power supply unit (PSU). Not all manufacturers take safety considerations seriously when designing 3D printers.

Change Out Tinned Wire Inputs

Some 3D printer manufacturers used tinned wire inputs on their 3D printers but this is advised against. The main reason for this is that the solder can deform over time and loosen when there is pressure on it.

If the connector starts to fall out, it can increase resistance and cause heat to build up at those connections.

With time, the heat generated can melt the motherboard and cause a fire outbreak. One user stated that using tinning wire ends is similar to lubricating the connection joint, leading to it eventually coming loose.

Check out the video below to learn more about tinned wires and how to install ferrules on them instead.

Use Strain Relief on Wires

Over time, wires connected to the moving parts of the 3D printers without a strain relief tend to undergo strain from the constant repetitive movements of the printer.

Most 3D printers have pretty good strain relief on their wiring, but if not, you should apply some to the wiring. Some good strain relief is to use a spiral wrap, a plastic conduit, or a drag chain to ensure the wire is rigid at the joints.

Can Resin 3D Printers Be a Fire Hazard?

Resin 3D printers can be a fire hazard just like any other piece of electrical equipment, but the chances are very low, especially compared to filament 3D printers. Resin 3D printers don’t reach high temperatures, but rather make use of a light source to cure layers. There isn’t much movement to displace wiring.

The stepper motors and fans do run constantly on a resin 3D printer, but there isn’t an extra fire risk like having a hotend or any overheating.

It’s really similar to something like an LED lamp, so a very low risk. I’d still recommend to have a smoke alarm and fire extinguisher just for general safety. The resin itself isn’t known to be flammable.

You want to make sure that your connections and wiring are secure

The biggest fire risk from a resin 3D printer would be from the post-processing with using isopropyl alcohol or any other flammable liquids. You can always choose to use a liquid that isn’t flammable, like when using water with water-washable resin.

Check out this interesting video that answers whether resin 3D prints can catch fire.

https://www.youtube.com/watch?v=90rm5IE_E90