Emergency lighting on contractor switched lighting circuits

[NigelMarsh]

I have been asked to get the emergency lighting working at a nursery. They had a switch put in at the entrance to the building that switches off all of the lights in the building when they lock up at the end of the day. All lighting circuits are hanging off a contactor connected to this switch, so they are cutting power to the light circuit MCBs and pretty much simulating failed circuits when using this, "master" switch.

whoever fitted this switch saw this and wired all of their emergency lighting into its own circuit to prevent it kicking in when the lights are switched off in the evening.

this obviously makes the emergency lighting pretty much useless for its main function.

they don't want to get rid of the master switch, but the want the emergency lighting to kick in when it's local lighting circuit fails. Doh!

Any ideas on how this can be achieved without losing the master switch, even if it means switching all lighting off using a different method? I'm going grey trying to come up with a simple solution.

:banghead:

 

[Plonker 3]

What's wrong the current set up if all the EM lights are maintained?

 

[Guest77]

I have been asked to get the emergency lighting working at a nursery. They had a switch put in at the entrance to the building that switches off all of the lights in the building when they lock up at the end of the day. All lighting circuits are hanging off a contactor connected to this switch, so they are cutting power to the light circuit MCBs and pretty much simulating failed circuits when using this, "master" switch.

whoever fitted this switch saw this and wired all of their emergency lighting into its own circuit to prevent it kicking in when the lights are switched off in the evening.

this obviously makes the emergency lighting pretty much useless for its main function.

they don't want to get rid of the master switch, but the want the emergency lighting to kick in when it's local lighting circuit fails. Doh!

Any ideas on how this can be achieved without losing the master switch, even if it means switching all lighting off using a different method? I'm going grey trying to come up with a simple solution.

:banghead:

Feed the emergency lights from the feed side of the contactor from the MCB, you can even add the test switch for them at that point.

 

[Knobhead]

If it’s 3Ph feeding the lighting contactor you will need a phase failure relay to monitor each phase.

 

[tazz]

As post 3, utilizing a bank of grid em keyswitches......if there are more than one phase, the warning signs that 410v is present should be displayed.

 

[Knobhead]

And if one of the phases fails, what then?

 

[tazz]

I cant see 3 phases feeding individual lighting circuits via the contactor, so if one phase was lost then em lights on that circuit would illuminate, and normal lighting would go out.....unlike control, its not dependent one all 3 phases

 

[Knobhead]

The reason I bought this up tazz is I’ve had two phases fail feeding a lighting contactor. ⅔[SUP]rds[/SUP] of the place blacked out and no EM lighting. To be honest I pulled the fuses to prove a point.
I don’t know who designed the set up but I know there was an arse kicking party afterwards. I don’t even know why I got involved, lighting and small power wasn’t my job.

 

[tazz]

Can see where you coming from..but here any phase that fails, will bring on the Em internal battery on that circuit, so even if all phases go out, it should course a problem...if it was a sustained central battery system, then this would need fail safe features

 

[UKMeterman]

What about feeding the perm feed via a contactor that has the coil fed from the same supply?

 

[tazz]

What about feeding the perm feed via a contactor that has the coil fed from the same supply?

Then you wouldn`t need a contactor

 

[UKMeterman]

Hi,
You have missunderstood, the em lights if they are the maintained type have a perm live feed and and a switched live feed. If the supply to daily switching contactor fails then the switched live drops out but the perm live from the local supply is still live, so the light is not lit even if there is a fault to the contactor. If you have a second contactor in the perm live, with the COIL fed from the same COIL supply as the day switching contactor then a fault will then cause the perm live to be disconnected and the EM run from it's battery.

 

[tazz]

Hear what you say...but the lights switching off with their charging lights still on, would be an indication of fault on daily switch feed, fault on perm feed would result in em coming on off their own battery.
Hope old diagram will show

 

[Knobhead]

Can see where you coming from..but here any phase that fails, will bring on the Em internal battery on that circuit, so even if all phases go out, it should course a problem...if it was a sustained central battery system, then this would need fail safe features

As I said, I had little to do with them but I think you’ve hit the nail on the head. There was a central battery room in each of the intake subs which fed out to the various plant subs.
I gave them a wide berth, the mates looked after lighting and batteries. The only time an electrician got involved was if one of the central lighting panels failed.

 

[tazz]

This is where you switch gear experience comes in Tony....but loss of a phase would be over engineering in this case

 

[Knobhead]

It was something stuck in the murky recesses of my mind.

 

[tazz]

It was something stuck in the murky recesses of my mind.

its called motor phase failure, and with dealing with switchgear....can understand the logic

 

[eNigMar]

Wow! This has taken off. I'm the Op, but I was informed this moring that I had two accounts and one had to go. I forgot about this second one, so let the one that I posted this thread as go. Hence me replying with this account.

It's single phase in a large converted house with two floors and a loft space. There are three downstairs lighting circuits, two upstairs and one for the loft. I don't do much in the way of emergency lighting and have only attended a days course on it out of interest, I was originally there to replace some broken outside lights, a few cracked sockets and a fluorescent batten in the staff room, but was asked about this.

The emergencies are non-maintained and I believe from what I've been told, were originally wired to the closest fitting, but when the contacter was put in for the master switch, they were all put on to their own single circuit (10x ELs).

I was thinking that if just one lighting circuit circuit died, if the emergencies were wired to the contacter feed, they wouldn't come on because they'd still have power. It would take the feed circuit to die before they came on.

Maybe updating to maintained lights would be the way to go.

Sorry about the late reply, it was my anniversary yesterday and I had to go do some anniversary stuff after posting.

 

[D Skelton]

Hey, this situation is exactly what this set up is designed for:



Key switch at the front door turns off all lights but leaving the emergency function intact.

Out of each lighting MCB (four of them) comes a feed which is then split across two seperate poles of the four DP contactors that you can see in this picture. The first two contactors (four poles in total) make up the permanent lives of the four emergency lighting circuits, the second two make up the switched live for each of the four emergency lighting circuits. The second two contactor's coils are controlled by the key switch, thus leaving the permanent live energised at all times, each permanent live and switched live fed from the same MCB remember. The first two contactor's coils are fed directly from the MCB for the control circuit/key switch meaning if the control circuit fails, the emergency lighting operates. The installation is essentially fail safe.

Apologies for the crap drawing, but below is a simplified version (one circuit) of what the picture above is doing:

 

[Knobhead]

Wow! This has taken off. I'm the Op, but I was informed this moring that I had two accounts and one had to go. I forgot about this second one, so let the one that I posted this thread as go. Hence me replying with this account.

Ask the moderators nicely to combine your other account with this one. You retain your post count that way.