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Wierd one....

tonydon
Hi everyone. 


So,  today we installed 6 new led panels in a new ceiling grid

The panels ar Ansell panels.  They are class 2. Low volt.


Then , our plumber says he has had a shock when touching the ceiling grid and a boiler at the same time.


So, we tested the ceiling grid to a local earth.   120V AC  or   -2.9V DC......   The grid  even lights a volt stick....


After trying several ideas I eventually swapped the live and neutral connections on the primary of the led drivers.......


The result..... no measurable voltage  between the grid and earth.......


The driver and the led panel are both marked class 2 ......


How is this possible??


Is it safe?


Do I need to bond the ceiling grid?
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    Going to have to find that  in the regs....lol



    Well I suppose in a way it's a section 543.7 kind of thing - even if in this case the leakage current isn't passing back through the c.p.c.


    I does occur to me that danger from electric shock depends on frequency as well as current/voltage. 50Hz a.c. is dangerous at a lower level than d.c. So what about these mutli-kHz drivers - should they be subject to the same 3.5mA/10mA limits as 50Hz? Might 543.7 be in need an update to catch up with high frequency switching technology (not just LED lights but VF motor drives and possibly the ubiquitous switchmode PSU etc).


    I would be interesting to know what Ansell's analysis and recommended solution is.


       - Andy.
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  • 0

    Going to have to find that  in the regs....lol



    Well I suppose in a way it's a section 543.7 kind of thing - even if in this case the leakage current isn't passing back through the c.p.c.


    I does occur to me that danger from electric shock depends on frequency as well as current/voltage. 50Hz a.c. is dangerous at a lower level than d.c. So what about these mutli-kHz drivers - should they be subject to the same 3.5mA/10mA limits as 50Hz? Might 543.7 be in need an update to catch up with high frequency switching technology (not just LED lights but VF motor drives and possibly the ubiquitous switchmode PSU etc).


    I would be interesting to know what Ansell's analysis and recommended solution is.


       - Andy.
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