Metal ceiling grid voltage

[Tetris1985]

100 volts on a metal ceiling grid when measuring from the Met to the ceiling grid

Only when lighting circuit (led panels ) is on it goes away if the panels are disconnected from the drivers and left on

Each panel has 25 volts from met to screws on the back they are class 2!!

So the voltage increase as panels are connected and decreases as they are disconnected

Are they just ---- panels that they leak that much

And is bonding the ceiling grid the only solution

Panels are about 5 years old

 

[Lucien Nunes]

Devices leak current, not voltage. The exact voltage present on the casing isn't terribly important or significant in and of itself, unless the leakage current is excessive. If the ceiling grid happens to be well insulated from earth and you are testing with a meter with a high input resistance, then quite a high voltage might be manifest even with perfectly normal leakage current per panel, especially as they are all tied together via continuity through the grid.

The drivers are class II, yes? How is the continuity then being established to the metalwork... through the driver casings perhaps? Can you test one or more drivers separately for leakage current to their cases? Can you post pics of the drivers and their spec?

 

[James]

Devices leak current, not voltage. The exact voltage present on the casing isn't terribly important or significant in and of itself, unless the leakage current is excessive. If the ceiling grid happens to be well insulated from earth and you are testing with a meter with a high input resistance, then quite a high voltage might be manifest even with perfectly normal leakage current per panel, especially as they are all tied together via continuity through the grid.

The drivers are class II, yes? How is the continuity then being established to the metalwork... through the driver casings perhaps? Can you test one or more drivers separately for leakage current to their cases? Can you post pics of the drivers and their spec?

Op notes that when the drivers are powered but disconnected from the panels, the voltage goes away.

 

[Tetris1985]

Devices leak current, not voltage. The exact voltage present on the casing isn't terribly important or significant in and of itself, unless the leakage current is excessive. If the ceiling grid happens to be well insulated from earth and you are testing with a meter with a high input resistance, then quite a high voltage might be manifest even with perfectly normal leakage current per panel, especially as they are all tied together via continuity through the grid.

The drivers are class II, yes? How is the continuity then being established to the metalwork... through the driver casings perhaps? Can you test one or more drivers separately for leakage current to their cases? Can you post pics of the drivers and their spec?

The drivers are class 2 yes

If you test from met to a metal screw on the unit you get any where between 15 to 50 volts

And met to ceiling grid 100v

If you bond the ceiling you get small sparks when the panel touch’s the grid when the circuit is on

Same small sparks if you connect the bonding to the met when connected to the grid and circuit is on

Not sure if it is the driver as the voltages goes if them panels are unplugged but drivers are left in

Multifunction tester

 

[Lucien Nunes]

Clearly the thing that is supposed to have good insulation and not leak excessively is the driver, as that has an SELV output that should be safe to touch. So there are two parts to this - are the drivers leaking excessively from primary to secondary, and why is the secondary circuit apparently in contact with the metalwork of the panel? The driver leakage might be HF, in which case the stray capacitance from the LEDs and their PCB / wiring to the casing might be sufficient to answer the second question.

 

[Tetris1985]

Clearly the thing that is supposed to have good insulation and not leak excessively is the driver, as that has an SELV output that should be safe to touch. So there are two parts to this - are the drivers leaking excessively from primary to secondary, and why is the secondary circuit apparently in contact with the metalwork of the panel? The driver leakage might be HF, in which case the stray capacitance from the LEDs and their PCB / wiring to the casing might be sufficient to answer the second question.

What would be the solution?

When the ceiling is bonded you can get a very small shock if you touch the panel screws and the metal grid. but testing between the screws to the ceiling reads 0 volts but I'm guessing with a multi meter that reads dc it would give a reading?

if you test from the ceiling unbonded with the lights on to a radiator you get 100 volts

 

[Lucien Nunes]

I would like to understand better what the problem is, before choosing a solution.

* Is the leakage to the drivers' secondary output within spec or are they faulty? E.g. if they are designed for a maximum of 0.25mA leakage and they are all measuring at 0.2mA the drivers themselves are in the clear, even though 30 of them producing 6mA aggregate leakage could produce visible sparks and raise the voltage from the grid to the kind of levels you're seeing.

* Is the panel metalwork somehow coming into contact with the SELV circuit in each unit, perhaps via pinched insulation, stray screws etc? If so, the individual 0.2mA leakage sources that ought to be floating and undetectable are all contributing to this aggregate.

If the driver leakage is normal per unit and the coupling is purely capacitive, then there is no real electrical hazard here and the solution is simply to earth the grid to discharge the nuisance current.

 

[cliffed]

Have checked there are no polarity issues elsewhere