[Doer1]

Can you switch Low voltage LED lights with a PIR? I'm looking at one of those deking kits that use a mains transformer as a power supply and want to automate them. Any Ideas? I have read a few posts but it doesn;t say how it was done.

[blicky_1]

Originally Posted by Doer1

Can you switch Low voltage LED lights with a PIR? I'm looking at one of those deking kits that use a mains transformer as a power supply and want to automate them. Any Ideas? I have read a few posts but it doesn;t say how it was done.

Yep no problem as you would just switch the transformer with your automation devices.

I have 16 12v garden lights that run off a transformer plugged into an X10 appliance module (controlled with Homeseer)

[Doer1]

Wont this just give me a timed on off? Our office's lights are controlled by a PIR so when you walk in the turn on????

[ZippyCat]

Could you clarify whether you are looking to switch the LED lights at home or at work? The reason why I ask is that if it is at work, then you will need to give a little more details on the lighting system at work if you were intending to switch them via the same system. Depending on how your office lighting is implemented, it could complicate matters if LCM’s (Lighting Control Modules) are used.

[Doer1]

Zippycat, Sorry at home I want to install some low voltage led lights in the stairs but wanted to switch them on when someone walks on them/ near them.

[ZippyCat]

In which case there will be no problem using a standard PIR to switch the transformer. Good luck with your project.

ZippyCat

[Doer1]

Originally Posted by ZippyCat

In which case there will be no problem using a standard PIR to switch the transformer. Good luck with your project.

ZippyCat

Would you use a 12V to switch the output or 240v to switch the mains?

[Johnny Thunder]

I would recommend you switching the mains.
Some transformers get hot when the secondary is open circuit.

[ZippyCat]

As Johnny says switch the 240VAC as opposed to the 12VDC.

[blicky_1]

Originally Posted by Doer1

Wont this just give me a timed on off? Our office's lights are controlled by a PIR so when you walk in the turn on????

Yes but if you used the wireless X10 PIR this will tell the module to turn on via the RF reciever.

[garyb9900]

The only problem you may run into is that some PIR devices have a minimum load and the load presented by the LEDs might not be enough.

[ZippyCat]

I have yet to come across any standard mains operated PIR that has a minimum load requirement, if you know of any please point me in the right direction. Crudely speaking a standard PIR is only a relay/contactor that is energised by a passive infrared device connected through a timing circuit. Once a relay/contactor is energised it can pass anything within its maximum rating, it’s really just acting as a switch. Granted there may be devices designed for more electronic type applications where transistors may be utilised, plus if there are thyristor type PIR’s available then you may have a valid point, but as long as Doer1 sticks to the B&Q/Screwfix type there won’t be any problems.

ZippyCat

[MULLY@110]

sorry to sound dumb here zippy but have you gt a pic of the pir you are referring to as am interested in doing something similar

[ZippyCat]

I wasn’t referring to any PIR in particular, however this one will work:

http://www.screwfix.com/app/sfd/cat/...80538&ts=88151

I do stand corrected ; some PIR’s do seem to have minimum load requirements, as seen below:

http://www.tlc-direct.co.uk/Main_Ind...tch/index.html

I’m guessing that the minimum load requirement relates to the wiring implementation, as no neutral wire is needed; the PIR is designed for a straight swap with a standard light switch.