emergency light

[clematis432]

Can anyone explain what the switched live connection in a self contained emergency fitting is for ? I thought this type of fitting only needed a permanent live from the same CB as the local primary lighting, the idea being simply when the local primary lighting supply fails, the supply to the emergency fails also and the self contained battery kicks in.
So what is the need for this switched live option ??
Thanks in advance.

 

[telectrix]

to use the fitting as maintained. i.e. for it to be on with the " normal " lights when the supply is healthy, and to activate as emergency light in the event of power failure

 

[clematis432]

Sorry, I should have said it is a maintained fitting. But surely it would be maintained. " on with the normal lighting" with only the permanent live connected ?

 

[malcolmsanford]

As Tel says a maintained fitting will be a normal light with an emergency circuit, so for these you will need a switch line to control the non emergency light.

a Non-maintained light will just have a permanent live to it that will not energise the lamp, but on failure of the supply the emergency circuit will activate.

http://www.esielectrical.co.uk/media/em_ltg_design.pdf

This is quite a good little guide.

 

[clematis432]

Still don,t get it (THICKO !) and have checked your guide and it confirms what I think (only a permanent live was connected in the schematic) Surely this is all that,s required to have a maintained fitting illuminated.
Please help me !!

 

[Colin Integrale]

I thought a maintained was on permanent i.e. cinemas.. Non maintained was only on during power failure and a sustained was a normal switched fitting with a battery back up.

I there any switching in there that would suggest it could do either of all three?

 

[johnboy6083]

there is three types of emergency lighting.

Maintained: the light from the emergency light is on, along with the rest of the lights, and then stays on when the power fails. It is possible if needed that you can link the perm live to the switch live if no switching is required, ie to illuminate exits permantly.

Non maintained: these lights are always off, until the power fails. Usually in these type of fittings, there is no switch live connection.

Sustained: these fittings have no batteries, unlike the two types above. these are fed from a central battery UPS system. This system can be more econimcal in large areas, as it save on replacing burnt out batteries in every fitting.

 

[malcolmsanford]

Still don,t get it (THICKO !) and have checked your guide and it confirms what I think (only a permanent live was connected in the schematic) Surely this is all that,s required to have a maintained fitting illuminated.
Please help me !!

A maintained fitting is the type you will get in an office. It will be alight all the time when normal power is on and when there is a failure the battery will keep it alight normally for 3 hours. The reason you have both a S/l and a LINE to it is, the switch line will operate the lamp under normal conditions, ie turn it on/off. The permanent LINE to the emergency side will stop the emergency circuit from energising when you switch the fitting off. Think if you only had a S/L then everytime you turn off the emergency circuit will energise.

When you have a supply failure ie loose the permanent LINE then it will energise the emergency circuit

 

[nickblake]

Sorry, I should have said it is a maintained fitting. But surely it would be maintained. " on with the normal lighting" with only the permanent live connected ?

It realy depends on the area its being installed in , say for instance exit lights maintained in community centers etc they may not need to be on all the time when the hall is not in use for instance but when its occupied then they are on ,also escape route where normal lighting is not required they are often used there ,some may be on permernantly some off and switched on, most maintained EL's have the option to be able to have the light switched or permernantly on, pointless having the permernantly on when the passage way is fully lit

 

[clematis432]

Thanks johnboy, You could maybe enlighten me further.
The maintained fitting I,m talking about, would require the permanent live to be linked to the switched live to illuminate permanently ?
Also, this switched live, if not linked, where would it be supplied from and what is the purpose of it ?

 

[nickblake]

Thanks johnboy, You could maybe enlighten me further.
The maintained fitting I,m talking about, would require the permanent live to be linked to the switched live to illuminate permanently ?
Also, this switched live, if not linked, where would it be supplied from and what is the purpose of it ?

Purpose is for switching the light on and off if the light was not used permernantly on read previouse posts

 

[malcolmsanford]

Thanks johnboy, You could maybe enlighten me further.
The maintained fitting I,m talking about, would require the permanent live to be linked to the switched live to illuminate permanently ?
Also, this switched live, if not linked, where would it be supplied from and what is the purpose of it ?

A maintained fitting is the type you will get in an office. It will be alight all the time when normal power is on and when there is a failure the battery will keep it alight normally for 3 hours. The reason you have both a S/l and a LINE to it is, the switch line will operate the lamp under normal conditions, ie turn it on/off. The permanent LINE to the emergency side will stop the emergency circuit from energising when you switch the fitting off. Think if you only had a S/L then everytime you turn off the emergency circuit will energise.

When you have a supply failure ie loose the permanent LINE then it will energise the emergency circuit

Did you not read this

 

[clematis432]

Thanks to all who answered, it has now "sunk in"

 

[clematis432]

Thanks to all who answered, it has now "sunk in"