Originally Posted by smac999
30ma would kill you in a heart beat. the deadly number is a lot closer to 5 then 30.
I am sorry; that is not true and I provide evidence below.
That sort of confusion leads people to use RCDs/GFIs that are too sensitive, hence they have nuisance trips, hence people bypass them and die as sabray´s friend. A 30mA whole-house RCD such as required in many countries would have saved the life of sabray´s friend. At most he would have had seized arm muscles for the 40 microseconds the RCD took to trip.
Many people (including myself, more than once and by my or someone else´s mistake and poor practice) have tripped a 30mA RCD/GFI when touching a hot wire and have not died. Isn´t that enough evidence? RCD salespeople have done that for "effect" many times.
Most developed countries, including most of Europe
, consider 30mA acceptable protection, and in a decent installation
nuisance trips are not an issue at that level. I am talking about respectable countries ranging form Germany
. If you want to read this in international standard look at IEC 60479, which considers 30mA adequate to protect against death by heart fibrillation and 10mA to protect against not being able to "let go" a live part, which is uncomfortable but not lethal.
If you want similar data from a US source you can look at the fourth slide in http://www.nema.org/Products/Documen...esentation.pdf
If you prefer a graph look at the following page from Schneider Electric
and see the chart that tells you that the probability of fibrillation after 40 milliseconds (standard time sensitivity of an RCD) only starts at 500mA.
Electric shock - Electrical Installation Guide
The same chart tells you that with 30mA the probability of fibrillation only starts to appear after more than 10000 miliseconds ie 10 seconds, which is way longer than the 40 milliseconds it takes for the GFI/RCD to operate. I feel tempted to make a bad joke about botched executions but that would not be appropriate given the post upthread.
The only reason to go down to 5mA is not to avoid deaths; it is to avoid discomfort and muscle seizures that last less than 1/10 of a second, but that happens at the cost of nuisance trips and not covering the whole wiring
system, which leads to accidents such as the one mentioned upthread.