Having just had a (brief) power cut whilst using the saw table I've been reminded of the need for an emergency light that comes-on when the power goes off. I've been meaning to make one for years but the right tuit hasn't appeared yet - so perhaps it's time to buy one. Any recommendations?
I have one of these
Its like a downlighter but check the clearance required at the back. Unfortunately I cannot find a data sheet and am away from the device at the moment.
I have mine fitted to the wooden panelling that boxes in the understairs space and so have have more than enough clearance.
Non-maintained? Bill
I wanted to replace the one I have next to my CU recently (it was due a battery replacement anyway)
I was not really happy with the location of it (to the side of the CU on a return wall), since it did not light the face of it that well, and also was no use for reading the electric meter. So I thought if I could find a slimmer one that could also be manually switched as well I could put it under the shelf above the CU.
Found this in the end:
(the green exit signage stickers don't come fitted - so you can leave them off if what you need is a light)
Aha! I hadn't considered a regular non-maintained emergency light because of the green signage - but if the signage is easily removed then there are lots of options, including some that are brighter than 3W (probably I'd want 10W in the workshop). Thanks. You mention "no NiCd", but surely there aren't any new ones out there still using NiCd ... ? Do these things switch-on instantly, or is there a delay?
A lot of them can be converted between being maintained/non-maintained, by adding/removing a link on the PCB, which is handy as you can wire in an external switch in its place, I have an architrave switch on my light under the stairs to see the consumer unit, and a wardrobe switch operated by the door of the cupboard in the box room to see the phone/router/switch/ups kit.
NiCd did/does still cling on for emergency lighting usage
instant
In the case of that one, the signage was even easier, it came not applied - it comes set of stickers you can attach yourself (and with the arrow oriented in the appropriate direction as required)
I would say the 3W LED is equal in output to the 8W striplight type it replaced. It would be plenty enough to see safely around a saw etc - but you might want more than one in large workshop.
There are also conversion kits that you can use to turn an existing LED lamp fitting into a battery maintained one:
Until relatively recently the fluro versions were powered with NiCds, so spares are available since it is a part that needs replacement from time to time, and the charging circuitry will not suit anything other than NiCd or NiMh:
Interestingly you can still get new LED ones with NiCd:
I would estimate that from power failure to lit is about 200ms. Curiously from manual switch on to lit is quite a bit longer - say about
800msAnother option would be a conventional UPS installed into the feed of the existing lights - that would maintain lights with no visible interruption. Just remember to fit an isolator *after* the UPS so you can work on the circuit safely since turning off the MCB will no longer do it!
fwiw other options... torch + mains relay candle on metal bracket
Yes, it only comes on when the mains power is removed.
I cannot remember what connections were made available when I fitted mine but a lot of non-maintained models can be configured as maintained with a single link.
A lot of the bulkhead type fittings still use ni-cad.
You may not find too many 10W devices as the "standard" seems to be to provide 3 hours of lighting on mains failure. This would depend on the capacity of the battery vs power taken by the light.
I believe that you can improve on that statement.
You only need an emergency light that comes on when the local lighting circuit fails.
For many years I've had a couple installed in my house and to be honest i didn't give too much thought to the life of the battery until I switched off all the electrics to do some work. The emergency lights came on but the one installed around 7 years ago only gave an acceptable light output for around 15 minutes before getting really dim.
Lesson learnt - test the light at least once a year to see how long it lasts when power is removed.
The failing light has been replaced with the one I linked to in a previous post and 3W gives more than adequate light for may hallway and in any rooms where the doors to the hall are open. Granted not every location has enough light to read a book but more than adequate to see where you are going without tripping over anything.
Thanks for that (needed) reminder :-)
Depends on how you want it triggered I suppose. There seem to be lots of these things that come on below a certain light level, but I suspect what you need is a light that either comes on when the power fails, or runs all the time but has a built in rechargeable battery to ensure it keeps going for a time after the cut occurs. Unfortunately, machinery does not come to a sudden stop when the power goes off. I'd imagine that something like one of those rechargeable packs powering a few leds might do the job. You could even have a wind up or pedal powered on if you wanted. Ahem. Brian
Or wire it into the mains powered smoke alarm circuit so can do doublw duty as a "smoke alarm circuit off" indicator?
Exactly what I did about 15 years ago.
I've a few similar to these dotted about the house
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