Emergency Lights

[HDRW]

I recently bought a "maintained" emergency luminaire, which has battery backup (obviously!) and an 8w fluorescent tube. I've noticed that the tube's filaments are glowing gently all the time the power is on (can be seen when the room light is less than bright) and feel slightly warm. Is this usual? Does it waste much power? What's the reason for it?

I understand "non-maintained" (just live feed, comes on when it fails) and "maintained" (live and switched-live, comes on when power fails or switch is on) but is there a scheme where the light comes on when power fails only if the switch is in the on position? That way it wouldn't bother coming on when there's a power failure when it's not dark!

(And I've always wondered why "maintained" is the name - what is being maintained?)

Cheers,

Howard

 

[Lectrician]

The light emitted is being maintained

No, the emergency part will always light when the mains supply fails.

There is also a sustained light, although these are not seen these days. Identical to maintained, except there are two light sources - a standard lamp, usually 240v, and a second lamp of lower illuminance, which activates on mains failure. OFten seen on old hotels with fancy light fittings etc.

Emergency lights are primarily used to illuminate exit routes during a fire - a smoke filled building will be dark during the day They are designed to illuminate as local circuits fail due to fire breaching the mains cables. This is why you don't wire self contained fittings in fire tuff etc.

 

[TrueBlue]

I understand "non-maintained" (just live feed, comes on when it fails) and "maintained" (live and switched-live, comes on when power fails or switch is on)

A maintained emergency lighting is a system in which all emergency lamps are in operation at all times but can be turned on and off. A non-maintained emergency lighting is a system in which all emergency lighting lamps are in operation only when the supply to the normal lighting or local and sub circuit fails. Sustained is two lamps one for emergency only the other for mains only.

 

[Steve]

I've noticed that the tube's filaments are glowing gently all the time the power is on (can be seen when the room light is less than bright) and feel slightly warm. Is this usual?

I wouldn't think so. Change the starter if there is one, and the tube.

The whole tube should be glowing - not just the ends.

 

[HDRW]

I've noticed that the tube's filaments are glowing gently all the time the power is on (can be seen when the room light is less than bright) and feel slightly warm. Is this usual?

I wouldn't think so. Change the starter if there is one, and the tube.

The whole tube should be glowing - not just the ends.

LOL! No, the ends glow only when the unit is off (a gentle orange glow) - when it turns on the whole tube glows as you'd expect. There is no starter - it's all electronic.

It could be that the filaments are kept warm so that the tube lights instantly when it turns on, which is just what you want with an emergency light - it's just not what I was expecting!

Cheers,

Howard

 

[JohnD]

I think we used to see that on the older emergency lamps in the theatre, but the new ones don't do it.

 

[Steve]

Now i think on, I have seen that heppen with these lights before. But being "maintained", one would hope it would be on all the time - for the purpose of guiding people out when the power is still on but other lights are dimmed eg. in a bar or club.

And the non-maintained lights I have used do light immediately anyway, without pre-warming.

Does this fitting have a red "charge" LED on it? perhaps it uses the filaments to indicate healthy charge? But as it gives no "useful" light when the power is on, it is no good as a maintained fitting, if one has been specced!

 

[Lectrician]

Sounds broken to me!

The filaments will ware out quickly if continuously warmed!

This often happens when the lamp isn't fully 'turned' into the lamp caps on some types of fitting.

 

[JohnD]

?Filaments?

 

[Lectrician]

Cathode

 

[Spark123]

But being "maintained", one would hope it would be on all the time

Maintained (self contained) emergency lights normally have a Ls terminal which can be used to switch it on and off in normal operation, it will illuminate in the case of power failure regardless of the state of Ls. If continuous operation is required, a link can be fitted between L and Ls.

 

[TrueBlue]

It almost sounds as if the light is connected incorrectly and when you are switching it off the battery is trying to light the lamp (clutching at straws a bit here, but you never know) . Are you sure it's connected properly? Probably is, but it wouldn't hurt to check.