emergency lights

[kevplumb]

seeing as the power goes out here at regular intervals
i was thinking of fitting some sort of emergency lighting

my thoughts are

6v batt on a trickle charger connected to 6v led downlighters

problems ?

1 is it feasable ?
2 what is the unit called that switches them on if the power goes out ?(does it have a different name in the states(buying stuff here is a nightmare)
3 rough idea of cable size (still using stranded here)?

hope this is enough info

 

[holmslaw]

The problem you're going to have is duration of the light batteries. They're only designed to allow safe escape from a building, so in uk they are rated at 1 or 3 hours, can't imagine that USA would be much different.
OK, you could knock something together to last longer, but is it worth it?

The proper solution is a small generator that can connect directly to your mains wiring.

 

[plugwash]

The problem you're going to have is duration of the light batteries. They're only designed to allow safe escape from a building, so in uk they are rated at 1 or 3 hours, can't imagine that USA would be much different.

Self contained emergency lights do indeed have a relatively short lifetime, OTOH if most of your power cuts are only half an hour or so they may be the easiest soloution.

The proper solution is a small generator that can connect directly to your mains wiring.

IMO a generator is a stupid soloution for just lighting, auto start generators are not cheap and I doubt they will be efficiant at such light loads either. Plus generators tend to be noisy.

1 is it feasable ?

Probablly, just make sure your LED downlights can tolerate the voltage fluctuations of a battery system (see also reply to point 3)

2 what is the unit called that switches them on if the power goes out ?(does it have a different name in the states(buying stuff here is a nightmare)

There are several ways to do this but the easiest is probablly a changeover relay. Either get one with a mains coil or use a wall-wart to supply the coil. Then when the coil deenergises the relay switches over and connects your batteries to the appropriate lights. If you want you could use the other side of the relay to connect the lights to a mains derived supply when the power was on was well.

3 rough idea of cable size (still using stranded here)?

you really need to figure out your current, distance and acceptable volt drop. From this you will be able to calculate cable size (volt drop WILL be the limiting factor)

It may make more sense to use a higher voltage for the batteries and then use DC-DC converters at each light. Especially if you plan to build a centralised system. This will allow the use of much smaller cables and should also be able to supply a more consistent voltage to the lights. Downside of course is the losses and cost of the converter.

 

[maltaron]

The simple way is to use an emergency lighting unit. These include the battery, charger, switching system and usually either two miniature fluorescent lamps or two small floodlights. I use one of these in the loft with the tubes removed and cables extended to 2 caravan lights with the guts removed, one in the kitchen and one in the bathroom.