UPS on light circuits

[uksparks]

Hi,

I have not thought this through yet so don't give me stick yet.

I was just thinking of putting emergency lighting around the house as saw some really slick little LED things which are very discrete, anyway, it made me think, well why not just stick a UPS supply next to the consumer unit to feed a or many light circuits??

Like I say, I have not thought this through yet, but was thinking of using something like a 11 pole relay so you can switch live, neutral and earth.

So you would have a relay which is normally open and the mains grid supply would hold it closed, when the grid dropped out, it would switch to the UPS supply.

The grid would go from the consumer unit, via the RCBO, through the relay and out to the lights, the UPS supply, would be powered from one of the light circuits, the load side of the UPS which would be the offline supply for the lights so to speak, this would then go back into the enclosure via a 30mA RCD.then onto the relay to the light circuits.

Now the only thing would be, at present, lets take three light circuits for example, they are all standalone separate circuits with RCBO's, if i connected them to relays, maybe through in an MCB inline with each for good measure, im just thinking, they will all end up common back one on RCD unless i put at RCD or RCBO on each light circuit and didnt feed the UPS from one of the light circuits, but an MCB on its own.

I guess i would link out all the A1 - A2 terminals to pull each contactor on, so they are all piggy backed off each other so they all switch together.

Can anyone see any issues with this? The other thing i was thinking was what about if the grid was still on and the lights tripped say? would it be a problem running the lights off a UPS whilst the rest of the house is on the grid?

I appreciate UPS supplies are more designed for computers and the like, but I also don't see the problem in doing this.

The other thing i was thinking, would you switch the earth as well? or not? Not sure where the earth would come from if i did switch it to the UPS? Presumably its common with the Neutral?

What do you think? I know it sounds crazy.

 

[uksparks]

Just need one of these on the bottom (obviously AMD3 compliant when the door gets updated)

Hager JK116EG Din Extension Box 16 Module

 

[spark 68]

I did have at one time a white paper with the different categories of UPS, but that was over 10 years ago so god knows where it is now lol.

There were basically two main types if I recall with further sub divisions.

The most expensive were the type that converted (rectified) the incoming mains to DC and then used an inverter (and a backup battery) to give the AC output, I think this type was called the full or dual conversion type, the bypass mode was not used via AC in and out, if the mains failed the switching was done at DC level between the rectifier and the battery pack.

The cheaper types used a bypass mode between the AC in and out, this was the type I mentioned earlier.

Then you have expensive types with pure sine wave outputs and some (most) of the cheaper types kick out more of a stepped square wave called an approximate waveform , sometimes this can be important depending on the application.

When designing anything other than single computer/server backup plug and play types it is important to know exactly the topology of the UPS you are intending to use.

If I find (unlikely ) that white paper you are welcome to it, the actual regs may have changed slightly but the physics and actual electrical principles have stayed the same.

 

[shanky887614]

bassically the cheap ups are off and only turn on and take over when power goes off but this has draw backs for example the voltage drops then spikes during this period.

the other type powers everything off the batteries and just uses the mains to charge the batteries


i know there more complex than that but thats bassically it dave over on the eevblog explains them a lot better (eevblog on youtube)