I know the following hints are always annoying and seem unnecessary. But unfortunately many people who knew it "better" from carelessness lost their eyes, fingers or other things or hurt themselves. Therefore, please take five minutes to read the safety instructions. Because even the coolest project is worth no injury.
The projects described here are designed for development, research, teaching and prototyping purposes only! You are responsible for compliance with the technical regulations.
Dangers due to electrical voltage or current:
When handling products that come into contact with electrical voltage, you must observe the valid VDE regulations, in particular VDE 0100, VDE 0550/0551, VDE 0700, VDE 0711 and VDE 0860. Never work under voltage. If you are not sure whether voltage is applied use a voltmeter to determine the absence of voltage. Also pay attention that some components can store electrical energy. Be sure to wait at least five minutes after disconnecting a device from the power supply until you open the case or work on the circuit.
Live cables or wires to which the device, component or assembly is connected must always be inspected for insufficiency or breakage. If a fault in the supply line is detected, the device must be taken out of service immediately until the defective line has been replaced. When using components or subassemblies, strict adherence to the specifications for electrical parameters specified in the relevant description must always be pointed out. If this description does not clearly indicate to the non-commercial end user which electrical characteristics apply to a component or assembly, how to perform an external wiring or which external components or accessories may be connected and what connected loads these external components may have, then a specialist must always be requested to provide information. Before commissioning a device, it must generally be checked whether this device or module is basically suitable for the application for which it is to be used!
In case of doubt, it is absolutely necessary to ask experts or the manufacturers of the assemblies used!
For installations and when dealing with mains voltage, the VDE regulations must be observed. Devices that are operated at a voltage above 35V may only be connected by a specialist. In any case, it must be checked whether the kit or the circuit board is suitable for the respective application and location and/or can be used.
The person who sets up and completes a circuit or a kit or makes an assembly ready by extension or housing installation, according to DIN VDE0869 as a manufacturer and is obliged to include all accompanying documents and to give his name and address when passing the device. Devices that are assembled from kits themselves are to be considered as an industrial product in terms of safety.
For all personal injury and material damage resulting from improper use, it is not the manufacturer but the operator who is responsible. Please note, the operating and/or connection errors are outside of our inflow area. Understandably, we cannot accept any liability for any damage resulting therefrom.
Dangers due to high temperatures
Please also note that soldering iron, hot glue gun, hot glue and hot air guns can become very hot (up to 500°C) in certain places. Be particularly attentive while working with such tools and create a quiet and tidy working environment.
Use a heat-resistant surface in your work, and be careful not to use the hot tools unattended or near flammable materials. An easily accessible fire extinguisher is also a very good investment.
Dangers due to Sharp-edged objects
Furthermore, please note that carpet knives, scalpels, glass edges, drills, SMD tweezers and workpieces can be sharp and very spiky. Always work "away from the body" and make sure that if you slip off with a knife (etc) you can never hit a body part or other sensitive objects.
If you separate component legs, pin headers or similar, make sure that the separated pieces fly very far and can also go to the eye. Wear safety goggles if necessary.
Dangers due to small objects
Many components are very small and can easily be swallowed by children! Make sure that young children are not able or willing to access these components, as they can easily be swallowed or inhaled.
Dangers due to machines and rotating masses/machine parts
When working with machines, please always make sure that you wear goggles and ear protection if necessary. If you are not sure if goggles or hearing protection are needed, you better start with both. Protective goggles are easier to remove after work than to replace an injured eye. Loud sounds and environments often show their consequences years or decades later. That's why you should avoid any noisy environment or protect yourself accordingly.
For working with fast spinning machines, you have to take off your gloves and make sure no part of your clothes can be pulled into the machine. Especially the cords of "hoodies" or long hair like to get caught up in machines. What can be particularly disastrous is that the machine can then pull your head/face into the machine. Even loose-fitting shirt or jacket sleeves can easily be caught by rotating machine parts. So make sure that nothing of you in any way caught by the machine or otherwise get tangled. If possible, try to cover as many rotating parts of the machines as possible so that touching them is not possible from the outset.
If you need to guide a workpiece by hand, always make sure to use an extension and keep all body parts as far away from the danger zone as possible. This applies in particular to circular saws or other material-removing machines.
Dangers due to data loss
Data loss is actually no real danger in the private sector. At least this causes in the rarest cases a danger to humans.
Data loss is almost always annoying. Because even in the best case at least some time goes on it to undo the consequences of data loss. Restoring a database backup, for example, takes a while, depending on the size of the database.
But there are also cases where this is no longer possible. Have you deleted your family photos of the last 20 years without having previously created a backup, these data are lost forever.
Especially with photos or other personal documents, this is particularly tragic.
That is why it is important to make backups of all relevant files as often as possible and necessary. If you make potentially critical changes (which could lead to data loss) to a system, make a backup in advance. Even if you think "Oh, that'll be alright". Backups are the only effective way to counteract persistent data loss. That's why: Regular backups of all important files will ultimately save you time, nerves and often money.
Hazards due to insufficient ventilation
Air polluting vapors, mists, smoke and dust may irritate or injure your eyes, respiratory system and skin as well. These are produced, among other things, when cleaning objects, gluing, soldering, welding, filing, cutting, grinding, sawing, milling, polishing and even 3D printing.
Therefore, make sure that you always work in a well-ventilated area in the case of this work. Work where large fumes could occur should always be done outdoors if possible. If this is not possible you should ensure that the resulting impurities are extracted. In any case avoid even short-term inhalations of these air pollutants.
Danger from flashes of light and flickering
Some people may experience epileptic seizures when exposed to specific light frequencies, flickering light sources, or geometric shapes and patterns. Certain frequencies of light can trigger an epileptic seizure in these individuals. Even commercially available LEDs or other light sources can generate these light frequencies.
If in doubt, consult a doctor if you or one of your family members is suffering from epilepsy before performing any work that may cause flashes of light. Immediately stop work related to flashes of light and consult a physician if any of the following symptoms occur: impaired vision, eye and muscle twitching, loss of consciousness, loss of orientation, involuntary movement and convulsions.
Dangers from handling permanent magnets
Permanent magnets made of NdFeB ("neodymium magnets") are products produced using the sintering process which, due to the manufacturing process and their composition, are brittle. To avoid damage or even breakage of the magnet, these should be handled with particular care. In particular in the vicinity of other magnets, steel, iron or any other material that the magnet could attract, care should be taken that it does not suddenly hit the material in question. In order to protect the eyes from splinters that may fly around, it is recommended to wear safety glasses.
That is why it is also advisable to apply the magnets to the adhesive base with great care, if possible by pushing or kinking them on. Never leave magnets loose on a non-metallic surface. The magnets could attract each other in an uncontrolled manner, damaging and splintering in the process. It is therefore advisable to always place magnets on an adhesive base or store them in a stack.
The high attraction of magnets can lead to considerable injuries to the fingers or other parts of the body if handled improperly. This can lead to bruises, but also broken bones. When in doubt, always assume that the magnet in question is unexpectedly powerful.
The magnetic fields of permanent magnets can - depending on the distance - affect the function of technical devices. This is especially true for pacemakers. Therefore, people with pacemakers should not be exposed to the influence of magnetic fields. Wristwatches, mobile phones or TV sets can also be influenced by the magnetic field of a magnet.
Magnetic fields are able to delete or corrupt data from magnetic data carriers, eg floppy disks, hard drives as well as bank cards and credit cards and thus make them unusable. Permanent magnets must therefore be kept away from such data carriers.
General tip for safe working
Always be attentive to all work and work calmly and conscientiously. Make regular breaks. Think before you do something. If you need help, get help. Ask once too much rather than too little. No unnecessary risks!
Sources and further information
Here's some additional information and links to reports of real accidents or "near-accidents". Especially from the accidents or almost accidents of others, much can be learned.