Building gear that uses mains voltage. Safety first!
Jul 24, 2013 5:47:02 GMT -6
horvitz, allbuttonmode, and 1 more like this
Post by Deleted on Jul 24, 2013 5:47:02 GMT -6
Dear fellow DIYers and potential DIYers....
Let's come to a topic of caution. Building and testing gear that works with mains voltage.
I have survived many shocks by mains voltage 220V AC, additionally shocks from loaded capacitors that i thought were safe, which were worse and some higher voltage shocks from tube psu's. All in very early times of DIY (and some from early 'electrician' household repairs).
Yes - each of one could have been lethal, potentially.
Still, I never say it could never happen again. People do silly thinG(B)S. All the time. Nobody is perfect.
I am aware of that. Therefore - never feel too safe or you will make mistakes that could end up lethal in the worst case.
Some good advices to be made concerning PSU building and working with mains voltages:
- Always check if mains is connected first. Before doing anything.
- Drinks do not belong to the workbench. Put them somewhere else. Floor, other desk, whereever....
- One hand in the pocket as soon as mains is connected.
- One probe of the multimeter clipped to ground/case, crocodile probe, the other one measures voltages. That's all that should be done when mains is connected. Period.
- Never work with mains voltages if you are tired. You might do silly thinG(B)S.
- Never touch the case with one hand when doing something inside a unit with the other one and not sure that mains is off.
- Huge capacitors are not safe if mains is disconnected. They have to be uncharged before considered safe. Disconnecting from mains is not enough.
- High voltages can be lethal due to the shock they provide to the nervous system. Voltages that can be considered nearly safe are as low as 50-65V. Everything above can do injuries or can be lethal.
- High currents can be lethal due to the effects they do to the heart and due to paralyzations that prevent breathing. Danger can start at currents as low as 30mA DC and 10mA AC.
- Combinations of both can be lethal.
- If you had a shock by high voltage/current and you do not feel good, puzzled or even had a blackout, immediately go to a doctor, a hospital (don't drive by yourself, take a taxi) or call an ambulance. Even if you feel totally OK, you might have taken a heart damage and that could still lead to serious injure or even end lethal later on. Ventricular fibrillation is not the only possible complication. You might get cardiac arrythmia later on and this can still end lethal. In all cases, a doctor should make an electro-cardiogramme to be sure you are OK.
Feel free to post further comments on the topic...
Best regards,
Martin
Let's come to a topic of caution. Building and testing gear that works with mains voltage.
I have survived many shocks by mains voltage 220V AC, additionally shocks from loaded capacitors that i thought were safe, which were worse and some higher voltage shocks from tube psu's. All in very early times of DIY (and some from early 'electrician' household repairs).
Yes - each of one could have been lethal, potentially.
Still, I never say it could never happen again. People do silly thinG(B)S. All the time. Nobody is perfect.
I am aware of that. Therefore - never feel too safe or you will make mistakes that could end up lethal in the worst case.
Some good advices to be made concerning PSU building and working with mains voltages:
- Always check if mains is connected first. Before doing anything.
- Drinks do not belong to the workbench. Put them somewhere else. Floor, other desk, whereever....
- One hand in the pocket as soon as mains is connected.
- One probe of the multimeter clipped to ground/case, crocodile probe, the other one measures voltages. That's all that should be done when mains is connected. Period.
- Never work with mains voltages if you are tired. You might do silly thinG(B)S.
- Never touch the case with one hand when doing something inside a unit with the other one and not sure that mains is off.
- Huge capacitors are not safe if mains is disconnected. They have to be uncharged before considered safe. Disconnecting from mains is not enough.
- High voltages can be lethal due to the shock they provide to the nervous system. Voltages that can be considered nearly safe are as low as 50-65V. Everything above can do injuries or can be lethal.
- High currents can be lethal due to the effects they do to the heart and due to paralyzations that prevent breathing. Danger can start at currents as low as 30mA DC and 10mA AC.
- Combinations of both can be lethal.
- If you had a shock by high voltage/current and you do not feel good, puzzled or even had a blackout, immediately go to a doctor, a hospital (don't drive by yourself, take a taxi) or call an ambulance. Even if you feel totally OK, you might have taken a heart damage and that could still lead to serious injure or even end lethal later on. Ventricular fibrillation is not the only possible complication. You might get cardiac arrythmia later on and this can still end lethal. In all cases, a doctor should make an electro-cardiogramme to be sure you are OK.
Feel free to post further comments on the topic...
Best regards,
Martin
