3 core plus earth to 2 core led panel

Hi
I am replacing a commercial fluorescent tube light fixture with a LED panel on a suspended ceiling. I've done a few which were simple connection but noted one of the fixture is connected with a 3 core plus earth cable. The black wire is mentioned on a sticker with a warning as an unswitched supply.
What does that mean and how can I connect it to 2core led panel. Thanks

 

An unswitched supply means what it says, a supply that is not switched on and off. Typically such a line would be associated with emergency lighting provision,

 

How is it currently wired?

If it's connected to something, it may be a light with an emergency light built into it.

In which case it sounds like your new light is incorrect...

 

Thanks I think it is a built-in emergency light because when I switched the MCB from mains one of the tubes was still lighting. But how do I replace it with an LED panel

 

With a LED Panel Light with Emergency Battery Backup, which will have the same connections. Or put permanent line in a connector block and don't use it.

 

Is this inside a Commercial property / building? Is there a flick test switch in the circuit?

 

Its an emergency light for a reason, you should not remove it, you either get an emergency version of your led panels or fit your normal led panel and a standalone seperate Emergency fitting.
If its a commercial premises then it needs doing right

 

If this is in a commercial building or an HMO ( House of Multiple Occupancy ) ( as Chivers mentioned ) then it is likely to be a LEGAL requirement that this lamp does light up when there is a mains failure/

 

And if the OP is the person fitting it in a commercial or HMO property, then he is clearly not qualified to do so if he is asking questions on here.