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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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    I think it mite be due to leakage through a capacitor which is wired between the negative side of the rectifier and the low voltage DC output negative it's there to cancel out the capacitive coupling of high frequency noise thru the transformer. Many switch mode supply's bite because of this one unit I've got has nearly 100 volts AC on it DC output leads both are at the same AC potential so there's no current flow  however its presence means that my fone could bite me while it's on charge ouch!!
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  • 0
    I think it mite be due to leakage through a capacitor which is wired between the negative side of the rectifier and the low voltage DC output negative it's there to cancel out the capacitive coupling of high frequency noise thru the transformer. Many switch mode supply's bite because of this one unit I've got has nearly 100 volts AC on it DC output leads both are at the same AC potential so there's no current flow  however its presence means that my fone could bite me while it's on charge ouch!!
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