Problem with maintained emergency luminaires

[Nick]

Have recently bought a bit of kit equipped with 3x Emergi-lite EWL38MPC maintained emergency lights. None of these work correctly. Not too ancient, datemarked 2008/09. All nicad batteries are accepting a charge. Same symptoms with all three. Lamp (new 2D 38W 4 pin) will illuminate from battery power but no signs of life from switched live. Have tried new starters, problem remains. Switched live is definitely supplying power to the ballast and capacitor. Tested. All other connections are good. Tested. The circuitry gets a bit complicated between ballast/capacitor and the emergency light unit which I presume is an inverter plus other gubbins. Would I be right in thinking that the inverter contains its own equipment to illuminate the lamp from battery power and that the problem lies with either the capacitor or the ballast on the mains voltage side? I don't want to bin these if the problem is a component problem that I can track down. If it is inverter unit associated then probably best binned That's the problem really. I don't know what the problem is. Thanks, Nick.

[Roger Mills]

ICBW, but I thought that emergency lights were only supposed to come on in the event of mains *failure* - with the mains being there just to charge the battery and to allow its failure to be detected. Am I missing something?

[Andrew Gabriel]

The mains side is relatively simple, and it sounds like that is the side which isn't working. I think there are only a few things which can be wrong:

One or both tube filaments burned out. It will probably still work on the inverter, but will prevent the mains switchstart working. (It's not good for the inverter either, as tube voltage will be higher than expected.)

Starter not working (but you already tried substitution).

Ballast burned out (gone open circuit).

If the unit has a relay to switch between mains/inverter, that might not be working, or whatever the equivalent circuit is.

[charles]

Yes, it used to be "maintained " or "Sustained", but the terminology has probably changed. Only "sustained" ones were on all the time.

[alan]

Its the difference between maintained (light on all the time) and non-maintained (light on only during power cuts)

On many units its just a link on the mains input chock block that has to be made/cut to switch between modes. On other units its one or the other mode.

[Andrew Gabriel]

Maintained usually have a separate switched supply for the light to operate as a regular mains light which can be switched. The permanent live supply is the charging/emergency circuit.

The type the OP is talking about sounds like the emergency unit which is added to a regular fluorescent lighting circuit to run the tube at a low level as an emergency light. They used to be common, but other solutions are used nowadays.

[Brian Gaff]

Well assumedly the problem is not the inverter or it would not work from batteries would it? So they do not just run the light from the transformer/psu that does the battery charging then? That is what I'd do, as it would then need no switching, it would just carry on till the batteries died if the power was cut.

Brian

[Brian Gaff]

Well that is what I'd assume t and that would be very easy to arrange I'd have thought. If they need to be on all the time then it would need to have the switching disabled but be aware that the psu may not like running the lights and the charging at the same time in any case. Best i can suggest is a psu that can be added to power the inverter when the mains is on. Brian