Emergency variant of normal lighting

[TickityBoo]

In the old days, it was relatively easy to spot an emergency light - dedicated units which were either maintained or non-maintained and self-contained or c.b. The maintained ones sometimes had a switch to turn them off when the building was unoccupied - usually hidden away beside the fuseboard. However, there seems to be an increasing number of normal lighting units, switched in an accessible place for everyday use, which also have an emergency supply - a sort of hybrid emergency light. 

I'm not talking about a sustained/combined luminaire as these have at least two bulbs - one dedicated to normal lighting and one dedicated to emergency lighting. I'm talking about one bulb shared for both normal and emergency use.  They are effectively maintained units (lamps are energized at all times when normal or emergency lighting is required) but are also designed to be switched on/off for normal lighting. 

What do people think of them as I am coming across them more and more frequently and sometimes they are switched off by well meaning members of the public. So if the fire alarm sounded, and an escape stair was without lighting, someone would have to fumble around trying to find the light switch - unless, of course, the fire took out the normal supply thus activating the emergency supply.

It is common for licensed premises to have maintained lighting - but I am concerned that with the proliferation of these "emergency variants of normal lighting" that these maintained lights can be easily switched off endangering the evacuation of occupants unless the fire takes out the normal lighting supply. (This wasn't a problem with dedicated maintained units where the switch was hidden away -  although the owner did have to remember to switch them on prior to occupation.)

[kurnal]

Not sure I understand exactly what you are referring to Ticketyboo.

There are many conventional light fittings for which conversion packs are available (comprising batteries, relays and inverters (where required) ) and provided these are installed correctly (wired to sense sub circuit failure, provided with test switch and charge indicator visible) they are a legitimate means of providing emergency lighting. Have you come across something different to this?

PS there are also some fantastic High intensity LED based emergency fittings on the market- their performance, size and longevity are breathtaking.

[CivvyFSO]

Tickity, I haven't seen any of these, I have seen what Kurnal describes though.

[AnthonyB]

From the OP's description i think they simply mean the conversion pack that is incorporated into normal fittings be it a  4 x 18W Fluorescent Recessed Modular Fitting, single Fluorescent batten fitting, 38W Round Bulkhead Surface Fitting, etc, etc.

Probably the most common way of providing emergency lighting now it cuts down on install time for a fit out & is more aesthetic as you can provide EL through some rather decorative fittings instead of the old ugly separate 8W 'brick'

It doesn't increase the OP's problem with lighting of escape routes as you had the same issue with the separate bricks if they were non maintained - the normal lighting needed to be on if it would be too dark to evacuate & the power hadn't tripped.

Some (but by no means all by a long chalk) old Central Battery systems where the pixie bulbs for way finding operated as non maintained did have a relay so that the fire alarm would cause the CB to change over to battery and light them without the power having to fail, but in most cases it was use maintained fittings or clearly sign your switches with 'light switch for fire escape' having said switches at each access point.

At one time buildings would happily leave the normal lights to the stairs, etc,  on all the time so this was never an issue, but in the current climate the trend is towards switching off where not essential, the fire stair being considered not essential by most management.

At the end of the day you have to risk assess the suitability of the set up based on occupancy type, etc and you will end up with various options:
- OK to leave off and rely on light switches, ensure all are signed clearly & staff trained
- Light essential so leave on all the time
- Light essential so fit PIR's to automatically fire it up when the route is entered (used a lot on general floor lighting in new builds for energy conservation)
- Light essential so fit timers to light up when borrowed light would become insufficient
- Light essential so provide Maintained fittings

True maintained fittings are exactly that and cannot be switched off - theatre/cinema type could be dimmed. Some EL manufacturers do provide a modern single bulb Exit Box & 8W brick that works like a two bulb sustained would have done, but it forms about 1% of the range and few distributors stock them.

What is prevalent is poorly wired shop fits where the manager's final exit keyswitch for after closing acts as a mains trip to the lighting circuit thus firing up the emergency lighting overnight rendering it charging for the first 8 hours of the day.

I've seen some new LED EL's from Olympus at Firex and they are very nice - good bright crisp output for low electricity consumption ideal for the Maintained fitting market

[TickityBoo]

True maintained fittings are exactly that and cannot be switched off

Thanks for your replies guys.  AnthonyB, you've hit the nail on the head.  I think BS5266-1 says that in areas of recreational premises i.e. pubs, restaurants, nightclubs, theatres, cinemas etc where lighting can be dimmed/turned off, maintained lighting may be necessary. 

Whilst I've seen "true" maintained lighting that can't be switched off, I've also been in nightclubs where they have dedicated s/c maintained units which have a switch next to the fuse board allowing the occupier to turn them off while the building is not occupied.  The battery live input is not affected and so the batteries still get charged (green led remains lit while the light is off). However, sometimes, the staff forget to switch them back on when they reopen the premises. 

I've always thought that n/m had to be wired to the local lighting sub-circuit so that they operate if the sub-circuit fails.  It is imperative that they are not on their own circuit as they will not operate if the local lighting circuit is lost. However, this doesn't matter with s/c maintained because they should be on all the time anyway and so can be on a separate circuit - they will continue to operate from battery if there is a general power failure or a local power failure affecting their own circuit - a power failure only affecting the normal lighting circuit will leave the maintained circuit operating from the mains.  However, if they're not switched on and they're on a separate circuit, you've effectively got  non-maintained lights that will not operate on a local sub-circuit failure. Phew!

However, in pubs/nightclubs where we have historically asked for maintained lighting, I am seeing normal lighting with conversion packs.  It's passed off as maintained because if its turned on when the building is occupied, it is providing illumination at all material times from the mains supply and has a battery back-up.

However, because these are normal light fittings, they have a switch on the wall allowing staff/public to switch them off.  I know you get the same problem with normal lighting / non-maintained lighting of stairwells, but where the lighting is supposed to be maintained to avoid this problem (as you suggest AnthonyB), these converted lights don't cut the mustard as "true maintained lights".

[nearlythere]

True maintained fittings are exactly that and cannot be switched off

 It is imperative that they are not on their own circuit as they will not operate if the local lighting circuit is lost.

Do you mean that they should not be on their own independant circuit TB unless interfaced with the local general lighting it is serving. Or the EL circuit should be paralleled with the general lighting circuit it is backing up?

[TickityBoo]

The bit you've quoted is in relation to my comments on non-maintained s/c units.  I understand why n/m s/c units cannot be on independent circuits - they must be wired directly to the normal lighting sub circuit to ensure they illuminate when the supply to normal lighting fails.  

My point is that maintained s/c units can be on a separate circuit: but if they've been switched off, they will only illuminate if there is a general power failure or if their own circuit suffers a power loss: they will not respond to a power failure affecting only the normal lighting sub circuit.  Therefore, if there was a failure of part of the normal lighting, these maintained lights would not illuminate as they are on a separate circuit.

What I'm trying to say is that normal lighting converted for E/L must be switched on so that light is provided in the event that a fire does not take out the local lighting sub-circuit.  There's more chance of the lights being turned off where the switch is a normal light switch on the wall, rather than a hidden switch back at the fuseboard which you occasionally get with a dedicated maintained e/l system.

Oh dear, I don't seem to be expressing myself very well.  Perhaps I need another beer?

[CivvyFSO]

There will be an assumption there that the normal lighting would be switched on if the areas were in darkness, but I can see how rarely used routes might not have the normal lighting switched on.

I guess it is down to the suitability of 'general fire precautions' ("measures for securing that, at all material times, the means of escape can be safely and effectively used")
and good old risk assessment.

[Mike Buckley]

My understanding was that the normal method was to include a permenant live wire on the lighting circuit which comes off upstream of the normal switch (with a key switch so it can be isolated) but downstream of any fuses circuit breakers etc.

Hence the emergency lights are always on charge but the normal lights can be switched on or off. If the lighting circuit fails, the permenant live fails and the e/ls come on.

[nearlythere]

My understanding was that the normal method was to include a permenant live wire on the lighting circuit which comes off upstream of the normal switch (with a key switch so it can be isolated) but downstream of any fuses circuit breakers etc.

Hence the emergency lights are always on charge but the normal lights can be switched on or off. If the lighting circuit fails, the permenant live fails and the e/ls come on.

That would be the same as parallelling off the relevant lighting circuit at the consumer unit.

[Mike Buckley]

I love it when you talk technical 

[nearlythere]

I love it when you talk technical 

Are you being suitably impressed or bemused by my B@@LS@@T?

[TickityBoo]

My understanding was that the normal method was to include a permenant live wire on the lighting circuit which comes off upstream of the normal switch (with a key switch so it can be isolated) but downstream of any fuses circuit breakers etc.

Hence the emergency lights are always on charge but the normal lights can be switched on or off. If the lighting circuit fails, the permenant live fails and the e/ls come on.

I agree - what you describe here is dedicated non-maintained e/l  wired directly into a normal lighting sub-circuit or "paralled off from the consumer board" as Nearlythere puts it.

However, I assume normal lighting converted for e/l use is wired more like maintained fittings ie. two live wires (one where the permanent live is charging a battery pack/other live is switched for the bulb??). I recently inspected a licensed premises in the evening which, as CivvyFSO says, had a rarely used escape route in darkness which had normal lighting converted for e/l use.  The normal lighting had been switched off at the wall by a member of staff to save energy.  Of course, if a fire had occurred which didn't affect the lighting supply, there would be no illumination unless somebody knew where the light switch was (in the dark) and turned them on.  The point is they should never have been turned off. Can these type of units really be thought of as "maintained" simply because they "can" be illuminated at all material times and will continue to function in the event of a supply failure?

The other (separate) issue was with a dedicated maintained lighting circuit which is not connected to the local lighting sub-circuit.  If the "secondary" live has a switch hidden away somewhere, staff can forget to turn them back on (the switch allows the lights to be turned off when the premises are unoccupied to save money/energy but still allowing the batteries to charge). In this case, if they're switched off, the batteries will continue to charge but the lamps will not illuminate on a failure of supply to the normal lighting circuit as it is a separate circuit. This is not an issue with n/m as they are wired directly to the normal lighting sub circuit.  However, a separate circuit only works for e/l where those e/l luminaires are on all the time thus negating the need to react to a supply failure of the separate normal lighting sub circuit.

I definitely need another beer!  Anyone want to join me?

[kurnal]

I recently inspected a licensed premises in the evening which, as CivvyFSO says, had a rarely used escape route in darkness which had normal lighting converted for e/l use.  The normal lighting had been switched off at the wall by a member of staff to save energy.  Of course, if a fire had occurred which didn't affect the lighting supply, there would be no illumination unless somebody knew where the light switch was (in the dark) and turned them on.  The point is they should never have been turned off. Can these type of units really be thought of as "maintained" simply because they "can" be illuminated at all material times and will continue to function in the event of a supply failure?

I agree this is not maintained emergency escape lighting. Its effectively seperate primary switchable lighing with  non maintained emergency escape lighting. If the RP wants to reduce his CO2 footprint the best way maybe to use motion sensors/PIR technology to enable him to ensure that the rarely used escape passage  has primary lighting when its needed.

Or extremely robust procedures to ensure that the the light will be on when the premises are occupied.(In your dreams). This in itself is wasteful of energy because a much lower level of lighting may be required for escape purposes.
I believe LED technology holds many of the answers.