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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: leakage current?? posted by Tweaker456 on September 25, 2014 at 13:12:40:
Tweaker456,
Safety Agencies DO NOT allow any unlimited amount of capacitance to be placed either across the AC line (H-N), or from Hot to Grd.
Placing large amounts of capacitance at these locations can result in potentially fatal current flow through a consumer if they are grounded while touching electrical equipment chassis or input/output jacks.
As far as I can remember, the leakage current limit for UL in North America is 3.5 mA. That flow would be the result of ALL capacitance's within the equipment, including X and Y AC line caps.
Equipment used in Hospitals or other sensitive areas have even lower leakage current limits, somewhere around 0.3 mA.
Most North American GFI AC outlets trigger at a leakage current of 5 mA, thus, any current that exceeds that would trip the GFI breaker.
Note that it is standard procedure to deliberately reverse the H and N lines during the testing for leakage currents.
Is this a common knowledge kind of thing? NO.
But it IS mandated by UL/ETL/CSA etc., and thus most insurance companies will void your insurance if they find out you deliberately modified equipment that then exceeds this amount of leakage current, and this caused a fire, death or injury.
From a practical real world standpoint, unless there is a grievous fault condition in a modern piece of audio equipment, relatively large amounts of capacitance placed across the AC line are not LIKELY to involve a negative result, but there is no guarantee that this will be the case for all scenarios, thus the Safety Agency stance on the matter.
For more on what leakage currents are, see:
http://www.powerlines.com/pq2005paper.pdf
and
http://www.mddionline.com/article/leakage-current-standards-simplified
Obviously, you as an individual can do whatever he wants, you can defeat a circuit breaker or fuse, you can add hundreds of uF of capacitance across the line, just don't expect to be covered by your insurance if you do these things, or be able to successfully defend yourself in a court of law if someone ever gets hurt if they are involved with your modified audio equipment.
Jon Risch
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Follow Ups
- RE: leakage current?? - Jon Risch 20:33:18 09/28/14 (0)
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