GFCI receptacles

[a10jp]

I have this question on GFCI receptacles. GFCI rating per UL 943, Class A stated that it should be 5 mA. NEC Section 210.8 stated that GFCI's operate on currents of 5 mA, with +/- 1 mA differntials allowed. Currently I am located overseas in Japan, and all the local products for GFCI's are rated at 15 mA. In Europe (Germany) also, 15mA are common place. My question is that whether 5mA is truly a necessity or merely a standard requirement. My question has to do with whether 5 mA is truly a safety issue that makes 15mA a clear violation. But then, if 15mA is truly unsafe, why would they be allowe to use in Gemrnay and Japan. Does anyone have any experience or know the history behind this argument?

 

[Skogsgurra]

There are physiological reasons behind the 30 mA limit in RCDs. Currents below 30 mA are not lethal, if interrupted within 100 milliseconds. So, European GFCIs have a "must operate" range 15 - 30 mA at a delay no more than 100 ms. I shall try and find the reasoning behind this - I know it exists somewhere.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

Skogs; It probably has to do with the electrical rhythm of the heart. The heart self triggers itself for each beat. It starts at one spot of the heart and then propagates over the entire surface then goes into a rest then it starts again. I suspect that 100ms is only a short part of a cycle and is much less likely to result in a chaotic rhythm associated with fibrillation and ultimately death.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Skogsgurra]

A few links:

http://www.havells.com/building-circuit-protection/RCCB.pdf

http://www.cis.unisa.edu.au/~cisdak/ResearchPapers/AUPECInteligEarth1996.ps

http://www.ieee.org/organizations/pubs/newsletters/emcs/fall05/emcabs.pdf

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

British requirements for an RCD providing personnel protection are trip at a value not exceeding 30mA and with a tripping time not exceeding 40ms at 5x nominal tripping current. The newer standards are BS EN 61008-1 and BS EN 61009-1.



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