Lighting question (3Core)

[JamesL2022]

I've been working in a shop today just replacing some lamps and fittings.

I had to replace a 2D light fitting that was at the bottom of a staircase. The light itself had three cables coming in. A three core to an emergency bulkhead and two three cores coming in. If I upload a picture of how it was wired can someone have a look and explain to me why it was done In Three core and what the browns and blacks are used for in this instance. I know the greys are neutral and green/yellow the cpc's.

I'm still learning so would appreciate the feedback and hope my question isn't a stupid one. If it is I'm sure I'll find out soon.

 

[Rocboni]

No such thing as a stupid question, we all have to learn.

Brown - Permanent live, to charge the Emg fitting batteries, if this is lost e.g power failure light will switch to battery backup,
Black sleeved brown - switch live to turn fitting on and off as a standard light
Blue - Neutral


Black and brown may be reversed depending on how the electrician wired it.

 

[JamesL2022]

Thanks for taking the time to reply. So all the black sleeved browns are switch wires? That maybe explains how the other two fittings on each landing of the stairs come on at the same time. It's just wired from a single gang switch with an emergency light fish key test built in. What was confusing me the most was all the switch wires. If you look at the bottom pic there's a single brown wire in the block with the two sleeved blacks that brown went into the live terminal in the light fitting along with the single black sleeved brown. What are those two connected blacks with brown sleeve doing, just keeping continuity of switch wires?

 

[Rocboni]

Depending on how it was wired, brown is maybe switched live and and black permanent live.

If the wire coming out of the fish key sw is brown, then the brown should go into the L terminal on the light and blacks should go to the SL terminal on the light provinding you are replacing the fitting with a emergancy fitting. If not then connect the black to the L on a non emergency fitting so it works with the single gang switch.