Todays job, flooded office. EM lighting question.

[ProDave]

Modern office building on an industrial estate, flooded due to burst pipe(s) above ceiling.

My job today was to isolate, and remove all the light fittings falling, or fallen from the sodden plasterboard ceilings.

Mixture of normal and EM lights.

But ONE of them confused me. It's a Thorn 5ft single flourescent non maintained EM light.

Connections are:

E- CPC's

N - blue

1 - 2 * brown

2 - black

3 - grey

So what's that all about then? I'm used to just Neutral, Live and switched live, so what's the 4th one then?

A seemingly identical fitting only had 3 connections plus E

I wasn't going to do any live testing (with water still dripping from the ceiling) today was just about making it safe.

But assuming I win the tender to put it all right, I'll be replacing this fitting so want to understand it.

Also something I learned today. Open plan office with Glued down carpet tiles. Once sodden they just slip with incredably low friction. You have to walk on them like you are walking on ice, or one will slide out from under you. Never seen that before. The guy there setting up the dehumidifiers and fans to dry it all out thinks they were glued down with the peel off backing paper still on them.

IP65 light are brilliant. If they fill up with water (through the cable hole) they fill up and stay full, no wonder they are so heavy and fall off the ceiling. One EM fitting, despite being full of water was still glowing!!!

There was also a Hager metal clad CU with water dripping off it. But removing the cover it looked dry inside (IP rating of top has been maintained) So do you think this will be okay, or should I be quoting to replace the main switch and all mcb's just in case they got wet?

I obviously want to present a fair tender to get the job but to do it properly and without doing anything unnecessary.

 

[Sidewinder]

Any doubt with breakers change them unless you can test them without destroying them!

 

[NozSpark]

I've replaced a whole CU given similar circumstances before,,, although water had actually been pouring through it

If in doubt rip it out it just not worth the risk.

 

[ProDave]

Thanks, I'll quote to replace the CU.

So nobody has come across a 4 terminal EM light before then?

 

[alpha spark]

Only time I've seen ought like this is when they've had a dimmable Klick box only a longshot probably a long shot though

 

[lkayelectrical]

You sure there's not another neutral as had before where there's 2 neutrals 1 for the pl and one for the sl

 

[Evans Electric]

That Fluorescent EM fitting Dave, Bovine droppings beats brains so declare it beggered up and charge for a replacement. ( Which will have Manuf. instructions)

 

[ProDave]

That Fluorescent EM fitting Dave, Bovine droppings beats brains so declare it beggered up and charge for a replacement. ( Which will have Manuf. instructions)

It's definitely beggered so will be replaced, so I will have the instructions.

I might have some investigating to do re the existing wiring to determine what the 4th wire is, a second neutral or something else?

 

[DJLSparks]

Were the connections labelled 1, 2 and 3?

Maybe switch dim system, but I think Thorn usually mark these D1 and D2...

 

[ProDave]

Labelled exactly as in post #1

No dimmer anywhere to be seen.

 

[SLIPSHOD & SLAPDASH]

Some older Thorn lights had a spare terminal to terminate the loop feed ?

 

[DJLSparks]

Switch dim system would have retractive switches local, not dimmers.

Only a guess but if you have 2 browns in L, then there is a 2 core and 3 core T and E at the light...so maybe the 3 core links to an occupancy sensor? Or internal lux level sensor.

Call Thorn Tech on 01388420042

They are usually really good.

 

[Megaohm7]

Been first fixing 3core earth and 2 core and earth to a track light system that is going to be dimmable apparently. It's a commercial job that I'm on at the moment. Majority of the lighting in the building is switched via Presence detectors and absence detectors. All new to me but learning lots in the meantime.