PIR Security Lights Question

Cmar-Ireland

First off, I'm not sure if this should be in the electrical sections or not. Searching for "PIR" showed more hits in this section!

Anyway,

I want to install some bulkhead lights along the side of the garage and at the rear of the house. 3 bulkheads and one small (150w) halogen. I want to use a standalone PIR sensor to switch these on together. Now the halogen will be 150w and the bulkheads maybe 60w each, so a total of 330w. Most of the good PIR's can switch 2000w without issue.
My question is, can I switch these lights on from two seperate PIR's?
That is if I have a PIR at the front of the house and one at the rear, can both of these be wired to switch the lights?

Thanks

10-10-20

Yes, if you wire it in a OR configuration.

                ______PIR1____
               |              |
Live ----------|              |-----LAMPS------Neutral
               |______PIR2____|

Cmar-Ireland

10-10-20 wrote: »

Yes, if you wire it in a OR configuration.

                ______PIR1____
               |              |
Live ----------|              |-----LAMPS------Neutral
               |______PIR2____|

Ok, so if I understand this correctly, I wire up both PIR's in parallel, with a live feed from both to the lights. Daisychain the lights together and then join to the neutral?

Correct?

Thanks a mill for this 10-10-20

10-10-20

Yes, I should have said 'in parallel'.
Don''t forget that earth must run to each device, and the usual disclaimers and warnings apply!

MickLimk

Cmar-Ireland wrote: »

Ok, so if I understand this correctly, I wire up both PIR's in parallel, with a live feed from both to the lights. Daisychain the lights together and then join to the neutral?

Correct?

Incorrect I'd say. You certainly don't want to daisy chain your lights, you want to wire them all in parallel, i.e. same live and neutral (and earth!) to all of them. If you daisy chain them (wire in series), then you will have varying voltages across each of the lights instead of 220-230v.

Cmar-Ireland

Ok, I'm taking the power from the garage lighting circuit. So I split the N from this circuit to each light. Then wire the L to the PIR's and the switched L from each PIR to the lights.

The bulkhead lights only have L and N no earth.

What happens if both PIR's are activated?



Does this look correct?

MickLimk

That will work.

I'd still run earth wires anyway. Your halogen will have an earthing terminal and there's always the possibility that you may change the bulkheads at some stage in the future to something that does have an earth connection. It's a lot easier to run in the cables now rather than retro-fit if needed later on.

It may work out easier for cabling purposes to run the switched live and neutral (& earth) to the first light (halogen?) and loop on to the other lights with 1.5 T&E connecting the lives, neutrals and earths together at their respective terminals in the light fixture. This is different from daisy chaining as all lights are getting the same live and neutral as they are in your jpeg. Whether or not you want to do this will be influenced by the layout of the lighting as well as the space available in each of the light fixtures for connecting in more than one cable.

You may also want to ensure that your MCB for your garage lighting can take the extra current. I know it's only about an extra 2A you're adding (3x100w bulkheads, 1x150w PIR) but it's still worth checking. Don't forget to use the right cabling. One other note, bulkheads usually come with heat sleeving for the wiring to ensure that the head from the bulb doesn't melt the pvc insulation, it's provided for a reason!

If both PIR's are activated it will still work fine. What it provides then is a parallel path for the current to get to the lights. Assuming identical PIRs and cabling, it just means that the current flowing to the lights is split between the PIRs with each carrying half.

Oh and I do reckon that this thread does belong in electrical!!

Avns1s

Remember your PIRs will need a neutral as well!

MickLimk

Avns1s wrote: »

Remember your PIRs will need a neutral as well!

Missed that one, sorry!

ircoha

Cmar-Ireland wrote: »

Ok, I'm taking the power from the garage lighting circuit. So I split the N from this circuit to each light. Then wire the L to the PIR's and the switched L from each PIR to the lights.

The bulkhead lights only have L and N no earth.

What happens if both PIR's are activated?



Does this look correct?

As noted earlier, the sketch attached to the above post is missing the neutral from each PIR so is not correct: am adding this in case others read from the bottom up

Cmar-Ireland

This is missing the earth to the halogen and pir's but apart for that is it correct?

Avns1s

Yep, that will work alright.

Dont forget your earth for the bulkheads.