EM lights behaving strange.

[Steve]

An electrician came to correct some faults yesterday at a newly built shop.

One such fault was in the office. The integrated emergency luminaire came on when the lighting was turned off (two no. 4 tube fittings)

So the man wired the EM fitting so that when the test switch was activated, one tube went off, and one stayed on EM mode, the other two weren't affected. This didn't seem right to me, and when I tested it myself, on putting the light back into normal service, the tube that was off glowed bright blue at both ends, and made an awful crackling noise, like welding After 2 seconds the whole unit shut down for half an hour, when it would reset.

What was actually happening to the fitting?

They have all been wired different, the same fittings throughout the back area of the shop. The warehouse lights, when tested, all go off. The canteen lights stay on all but one fitting, which is the EM. On the shopfloor, one circuit has been wired as the office was, so when the master on/off is turned off, the EMs come on.

I dont rate the sparks on this job. They left two lights with no prismatic diffusers in the warehouse, about 30 missing blanks on the main DBs, the above faults, lack of sockets in the office, a timer placed ABOVE THE CEILING, two circuits terminated to a single FCU, relying on an RCBO to isolate the one unused circuit (for a future addition)

 

[ericmark]

It does not need me to tell you there is something wrong.
I will guess missing wires. I have seen this before when someone has forgot to install cables and the commissioning spark does not want to admit he has a problem and will try anything stay off having to tell his boss what has gone on.

And I have worked on jobs where the boxes have been opened and left laying around and blanks, etc have been swept up, crushed etc.

Not always the fault of the spark on the job now. It may have been the one before him.

Best on I came across was on an airport where the control tower was at the flick of one switch able to black out the whole area. The firm installing the lights used relays for all the lights but they did not have the contract to install the cables from the tower under the runway to the accommodation block so to test and to prove their part of the wiring they put bits of card board to hold the contacts in on a temporary basis. On first testing the system no lights went out so on investigation we found cardboard which we removed but were unable to get the solenoid to energise. Neither could we find the plans which would have been produced as a as built by the contractor responsible for fitting the cables. So next step was find out who should have fitted them. At which point we found no one had been awarded the contract but by this time there was an active runway so they had to go miles around the runway with much thicker cable.

I have left jobs without lids on conduit boxes etc. Just because they had not arrived in time. Wrong I know but what can one do? One can only work with the materials provided. I have also walked off a job without curing problems as my flight to next job was booked and the firm refused to reimburse me the £100 if I stopped.

So you need to get the full story maybe it is the electricians but also it could be beyond their control.

Eric

 

[333rocky333]

So the man wired the EM fitting so that when the test switch was activated, one tube went off, and one stayed on EM mode, the other two weren't affected.

Four tube fittings sometimes have two twin HF units doing two tubes each.

Only one connects to the emer pack,and when the test key kills the

permenent feed, one tube goes off and the other will be on emer and dimmer.

The other two tubes fed from the other unit will stay on, as the switch

feed is still live.

Wired this way you can test them for 1/2 hour without leaving the area

too dark.

Usually any lamp or lamp wiring fault, would only shut down one

unit ,two tubes.

For all four tubes to shut down it would need to be a four tube unit, but in

test mode 3 tubes would go off and not just one.

There usually prewired though, and it sounded like he just got the perm

feed and switch feed wrong way round initially.

Did you see how many units in it, excluding the emer unit, and what

size/type lamp.

 

[Steve]

I will say, in the sparks defence, the place is crammed with PIR lighting control, integrated EM lights, contactors, fans, it must have been a headache to wire all this together correctly.

When you turn off the lighting in any of the back rooms, and back on, the PIR turns on the lights, then off 10 seconds later, then back on when it detects movement. Clearly the PIRs have been wired after the switch and they have to initialise.