Motion Sensors for 120 VAC security Lights - Electrician Talk - Professional Electrical Contractors Forum

czars · 02-25-2009, 04:19 PM

I have a need to control a single security light from multiple motion sensors each of which covers a different area. Has anyone had success in connecting more than one sensor in parallel to control a single light?

electricista · 02-25-2009, 04:36 PM

Quote:

Originally Posted by czars

I have a need to control a single security light from multiple motion sensors each of which covers a different area. Has anyone had success in connecting more than one sensor in parallel to control a single light?

Sure--- Here is what I did years ago on a long driveway. I used UF cable -I had a 2 wire feed at the first sensor and a 3 wire cable running thru each light to the last sensor. The black wire feed thru the jb's to the last sensor and the reds were the switch legs to each light.

Add: Be very careful that you do not create a parallel neutral or get unwanted EMF's

BryanMD · 02-25-2009, 05:29 PM

depends on how the layout is...
3wire homeruns to each MS or daisy chain between them as electricista said...
and back to a relay (controlling the light and whatever else they might want to go off)
(I like relays)

hayan453 · 02-25-2009, 08:50 PM

Separate homeruns so that the sensors are on different phasing im assuming? but what happens when both sensors are activated at the same time?

Never worked with relays either could you elaborate please? only worked residential for a little while.. mainly commercial stuff is all i do so i dont get exposed to this kind of stuff

electricista · 02-25-2009, 08:58 PM

Quote:

Originally Posted by hayan453

Separate homeruns so that the sensors are on different phasing im assuming?

I don't want to speak for Bryan but that is not my take on it. I believe he is suggesting a 3 wire cable back to the relay not the panels. The MS would kick in the relay and control the lights.

Quote:

Never worked with relays either could you elaborate please?

There are different types of relay but the basic relay has line and load contact points that are activated by the MS (in this case). If 120v is brought to the coil on the relay the contacts will close- lights go on. When the MS times out then the voltage is gone and the contacts open-- lights go off.

BryanMD · 02-25-2009, 09:07 PM

Quote:

Originally Posted by electricista

I don't want to speak for Bryan but that is not my take on it. I believe he is suggesting a 3 wire cable back to the relay not the panels. The MS would kick in the relay and control the lights.

There are different types of relay but the basic relay has line and load contact points that are activated by the MS (in this case). If 120v is brought to the coil on the relay the contacts will close- lights go on. When the MS times out then the voltage is gone and the contacts open-- lights go off.

close enough

also with a relay you can wire in an over ride switch and a time delay for how long they stay on all sorts of versatility

hayan453 · 02-26-2009, 08:44 PM

What is the benefit of having the MS activate the relay instead of the light? Is this the same idea as a DC current relay? 4 leads.. one grounded and the other the signal to activate the relay which in this case is the MS, (Something like this---> [Source voltage- = -Load side(light)] The equals symbol top line is EGC and the bottom line is the MS lead)???