4 outdoor lights + 3 PIRs with wired override backfeeding

[LightSpark]

Hi All,

I have a in issue with the outdoor lights I have wired up. They work but not as expected.

I have 4 lights operated by 3 different PIRs (see diagram). I want each light to be controlled by it's PIR but also to have ALL the lights to be operated from a 2 way and off override switch.

Switch position 1 - All lights on
Switch position 2 - Lights controlled by their PIRs
Switch position 3 - All lights off

As it stands I have it wired as per the diagram (Neutral has been omitted for clarity.)

Grey is the power to the PIRs and Brown is a direct feed to the lamps.

It almost works but when power is running to the PIRs via the Grey cable, All the lights are operated by ANY PIR due to power back-feeding through across the lamps, through the Brown live cable, which is undesirable.

* How do people usually do this?
* Is there a specific type (model) of PIR that will allow a bypass of the PIR unit (pass through)?
* Do I need to use relays in this setup?
* Am I the first person to attempt such a thing (I doubt it)?

Please don't anyone suggest that I use the PIRs with the quick on/off/on override system as I find this to be an awful design and a poor solution.

Any help is greatly appreciated.

Cheers

Outdoor Backfeed setup :(

• LightSpark
• 21 Mar 2013
• 1

 

[OwainDIYer]

To stop the backfeed you need to have a changeover switch on each PIR, with the common to the light, L1 to the PIR switched supply and L2 to the permanent live supply.

PIRs with c/over contacts are available for building management systems but I haven't found one for exterior use, so you will need to use a relay.

View media item 58780
The two lives from the 2-way-centre-off switch PIR and ON, and the Neutral, in parallel to each PIR/relay/lamp assembly.

 

[333rocky333]

1 four pole contactor / relay

for all on, sw pos 1 controlling coil and 4 feeds out via contacts all 4 linked on supply side , 1 out to each light, load side of pir

for pir use, sw pos 2 supplying 3 feeds out to the pirs, supply side

for off , no supply out to pirs or contacter

 

[ban-all-sheds]

Stuff that no real spark would ever need to ask on a DIY advice forum

As it stands I have it wired as per the diagram

With what sort of switch?

Any help is greatly appreciated.

• http://www.google.co.uk/search?q=electrical+circuits+101
  
  
• http://kevinboone.net/electricity.html
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
  
  
• //www.diynot.com/wiki/electrics:books
  
  
• //www.diynot.com/wiki/electrics
  
  

 

[Lectrician]

Am I the first person to attempt such a thing (I doubt it)?

I have not come across an installation that has been required to operate like this in my years as a sparky! Most people like to have all the lights come on from either PIR. Most PIR's are designed to allow this and state the maximum load they can tolerate when doing so.

If you really just want a single override switch and not 4 seperate ones, you would use a single four pole contactor as mentioned above, each pole acting as your four individual override switches.

You could either fit a two gang switch, first gang switching the power to the PIR live in, and the second switch powering the contactor which will override. The first switch could be a secret key operated type to prevent accidental switching.

Or fit an MK three position (centre off) switch. Up - PIR, Down - Override.

It would be easier to wire the above by wiring a three core from each PIR to the contactor, and a T+E from each lamp to it's PIR OR back to the contactor.

 

[bernardgreen]

Deleted and replaced with a better version

 

[LightSpark]

Thanks all for your suggestions.

* I am using an MK non retractive 3 position (2 way and centre off) switch.
* I have wired 3 core and earth to each pir/lamp position to allow for the 2 desired switched feeds.

I'll have a proper look at all your responses tonight.
What a helpful place!

Cheers

 

[bernardgreen]

Slight revision

Wire PIRs to the control switch using a triple and earth cable for each PIR.
Live, Neutral and Switched Live

Wire the lamps to the PIRs with twin and earth.
Neutral and Switched Live.

The control switch is three pole switch ( fan isolator switch )

Connect the three switched lives from the PIRS to OUT L1 L2 and N

Connect the live supply IN L1 L2 and N

N is normally Neutral when used as a fan isolator but in this application it is used as a third Live terminal. Ensure the cables to the N are clearly identified as live with brown sleeving.

 

[GarethW]

Lectrician and Bernard
You are both very talented people