Multiple sensors for internal lighting

[chloebear]

Hi All,
I have been asked to wire some lighting for an office and corridor involving sensor operation and Lighting distribution units and I was wondering what the best way of achieving this would be??

Briefly I will have 7 600x600 Grid lights in a corridor that will be operated by 3 sensors - when any of the sensors is activated the lights will operate. some of the lights will also be emergency lights.

 

[Hawkmoon]

1 Calc load
2 Sensors to suit
3 Wire switching circs in parallel
4 Perm feeds to EMs

If load too much for sensors, use contactor


Hope this is clear lol

 

[telectrix]

parallel the sensor outputs together. make sure they each can handle the total load. if not, use a contactor

 

[Hawkmoon]

parallel the sensor outputs together. make sure they each can handle the total load. if not, use a contactor

I am amazed I beat YOU on that one tel lol

 

[telectrix]

just got up. brain not yet fully functional till i've had a smoke.

 

[chloebear]

Thanks for the replies - so lets see if I've got this right??
Assuming that the load for the lighting is greater than the sensor loading. I could run a circuit out to the sensors and just parallel the sensors together on the circuit (L/N/E & S/L) and bring the S/L back to the contactor. Feed the lights from the contactor.

Do I need a separate breaker to feed the sensors and the lights via the contactor as the protection for the sensors will be less than for the lights??

 

[telectrix]

you select the protection device/s according to the load/s and the cable/s feeding the load/s. so if using a contactor, you might have a B6 for the sensors and a C10 or C16 for loads. you could even split the loads over 3 poles of a contactor.

 

[Hawkmoon]

Also may be easier to mount 6A mcb in enclosure with contactor - that way one feed, the 16A or whatever, can do both (only 1 way required at DB)

When you calc load don't forget multiplier (assuming standard fluorescents)

 

[Darkwood]

What traffic is there? .... if they will be switching a lot then fluorescent modulars will see a shortened lamp life especially if switch start...

Id be inclined to estimate the switching duty before choosing this method and/or choose an appropriate fitting like LED mods to give good service life.

Id wouldn't personally be switch the fittings through the PIR's even if they are within the PIR's switching capacity - PIR's are prone to failure of switching contacts and especially with accumulative inrush which is hard to calculate - a contactor is the best way ahead.

 

[Hawkmoon]

Best to go by manufacturer's info.

Look at the difference between resistant and inductive load rating of this:

Buy Newlec Standalone PIR Sensor, 180°, 12m, White - NLPIRW2A

 

[Zebra Stripe]

I wouldn't bother with a contactor for 7No 600x600 modular fittings.
Just use a recessed crabtree master & slave motion sensor… hard wire the master & plug in upto 5No slave sensors. I believe these will switch quite happily up to 1100watts of hf fluros, unlike the paltry 500watts of stand alone PIRs.

 

[Hawkmoon]

That looks a goer - even with the multiplier he is only looking at around 900 Watts (a guesstimate from post 1 info)