Dominator wrote:Jonno wrote:I don't get why everyone says that it should be a metal case. Am I missing something? As long as you earth the controller I see no problem
I guess with amateurs building these it was easer to say earth the case then to explain what, how and why.
OK I just sent this as a PM to another member asking me the same question .
I'm a TV tech not an electrician .
My main concern is that all switches ,potentiometers shafts and brass grub screws that hold the knobs on all have the potential to be live if they brake down internally .By having the case metal and Earthed then any exposed metal will be at earth potential .
Many constructors buy the cheapest components they can and you only need to pull them apart to see that there is often only a mm or less between metal conductors that are at 240V Ac and exposed metal actuators that if were in an unearthed plastic case could become lethal conductors in the unlikely event of a breakdown internally .
When I did my apprenticeship way back in 1983 in NZ we were told that things should be built in All earthed metal cases or double insulated plastic cases where all switch actuator mechanisms were to be of plastic or other non conductive material that protruded the case .IE anything that could be touched
Cheers Yummy
Also add that If we are bolting a a heatsink to a case I personally think it should be Metal Case .Things do get Hot .Things do melt . Metal dissipates heat much better than plastic .
If nothing ever failed then I would not have done an apprenticeship solely for the purpose of repairing brakedowns 8-}
Maybe I'm a pedantic wanker in this area but its all about building something as safely as we can :handgestures-thumbupleft: