3 core PIR into 2 core JB

[john wright]

Hi everyone.

i think i’ve read all the posts on this but i’m still stumped.

I’m replacing a set of 2 fluorescent tubes controlled by a PIR in my garage with a cluster of LED bulbs and want to retain the PIR.

i’ve taken the feed from my consumer unit to the i/o terminal of Junction Box. The JB is 2 core + earth with the following terminals:

2 in/out terminals
1 switch terminal marked SL-E-L
7 light terminals

The cable from my PIR is 3 core + earth coloured Black, White, Brown and naked earth.

How should i connect the 3 core?

i’m assuming it should go into the Switch Terminal. Is that correct?

Should i be joining two of the wires together into the SL terminal?

Any guidance greatly appreciated.

Stay safe everyone

John

 

[SFK]

John

For the PIR with its 3 core + earth coloured Black, White, Brown and naked earth, those cables will be
-Live (L) and Neutral (N) to power the PIR.
-And Earth (E)
-And Switched Live (SL) which goes live when the PIR is activated by movement - and sends Live to the Lights.

So to the Junction Box's "1 switch terminal marked SL-E-L" connect the PIR's Live to the hole marked (L), the PIRs Switched Live to (SL) and the PIRs Earth to (E) (The Earth cable needs a yellow sleeve to cover it).
You will then have to also connect the PIRs Neutral (N) to a suitable Neutral connection on the JB - use the (N) connection on one of the "2 in/out terminals".

Does your PIR say which colour cable is which? You may need to open the PIR to see how they are connected.

SFK

 

[john wright]

SFK thank you so much!

So with your guidance we have the PIR working...in so much that the infrared indicator flashes when it detects movement...but no lights are working

The only way i can get a light to work is by connecting it to the spare OUT terminal on the JB and that renders it permanently on...

Stumped again Any ideas?

J

 

[SFK]

I am presuming you are using one of these:
Surewire 7 Way Pre-wired Multiple Light & Switch Junction Box SW7ML-M
https://www.toolstation.com/surewire-7-way-pre-wired-multiple-light-switch-junction-box/p58205

When you say
"only way i can get a light to work is by connecting it to the spare OUT terminal on the JB and that renders it permanently on"
what is 'it'?



My quick test to see if wiring is correct without the PIR would be to remove the PIR for the moment.
Check that into "P O/I"_Section you have your supply voltage cable (L, N, E).
And into say "L1"_Section (L, N, E) you have a cable that goes to a light/bulb.
Put nothing into the "S"_Section for the moment.

With this setup there is a break in the Live supply cable to the Light/bulb, as there is no connection at "S"_Section between the "L" and the "SL" (the switch is off).
With the power on the Light will be off.

Then (after turning power off) put a single wire on "S"_Section between "L" and "SL" (Typo corrected).
This will make the Live circuit complete and when you turn on the power the light will be on.

 

[john wright]

SFK you are absolutely right I am using that JB! and thank you for the continued help. i really appreciate it!

“it” is one of the fluorescent strips i plan to replace.

Basically i have replaced 1 FL strip with the JB.

The PIR was previously connected to the FL strip i have replaced with the JB.

In the absence of any other guidance i’m going to pick up with your advice to remove the PIR and connect a lightbulb tomorrow morning!

Just one question: When you say “put a single wire on "S" between "L" and "SW". “...this terminal is marked E (earth) it’s ok just to connect a wire here with no device etc?

Warmest regards and thanks

John

Read more: https://www.diynot.com/diy/threads/3-core-pir-into-2-core-jb.541544/#ixzz6HiutwISR

John

 

[SFK]

I made a typo,
I said: put a single wire on "S"_Section between "L" and "SW"
Should have said: put a single wire on "S"_Section between "L" and "SL"
I have corrected this.

With regards to your Light being on when connected into the second "P I/O"_Section:
Yes that would be expected.
The two "P I/O"_Sections are directly connected to each other with no breaks.
So they are all powered up all the time.
When you put a Light into the "L1"_section, it is designed to not work as there is an intentional break in the Live wire in the "S"_Section.
The lights will only work when you connect, in the "S"_Section, the "L" and the "SL" connections together with a wire (or a switch) to fix this break in the Live.


With regards to your question:
"When you say “put a single wire on the "S"_Section between "L" and "SL". “...this terminal is marked E (earth) it’s ok just to connect a wire here with no device etc?"

"S" stands for switch.
In the "S"_Section the connections between "L" and "SL" is where a switch would normally go.
The test wire I am suggesting acts like a switch that has been closed, so when the wire is inserted it is completing the Live Circuit to the Lamps.
Without the Wire there is a break in the live circuit and the bulbs will not light.
During this test phase there is no need to have a wire connected into the "E" Earth connection of the "S"_Section.

With regards to the PIR:
The PIR acts like a switch. It takes the power in on its Live (and neutral to power it).
And it outputs Live on a different cable (know as Switched live "SL") when it is activated.

So I would connect the PIRs "L" and "N" and "E" onto the "P I/O"_Section to the right of the "S"_Section.
This will power the PIR.
And I would connect the PIRs "SL" to the "SL" connection of the "S"_Section.
The PIR will then send Swiched Live power to the Lights when the PIR is activated.

SFK

 

[john wright]

SFK it works a treat!

PIR working perfectly and now adding lights

Thank you SO MUCH for your help and clear concise guidance!

Stay safe in these difficult times.

John

 

[john wright]

...and then the 5 amp fuse at the consumer unit exploded with a really big bang!

So! SFK i wonder if you can help. I’ve added one light to the JB. worked great. Then i took the following steps.

1 Ran from L terminal in JB to Power I/O on a newly installed, 2nd JB at the opposite end of the room. (i need extra lighting.)

2 In 2nd JB connected a wire between L and SL on S terminal

3 Connected a light to an L terminal in 2nd JB

BANG!

Have been trying to correct via trial and error but i’m running low on 5amp fuse wire

John

 

[SFK]

Trial and error is a good way to get yourself killed.
And dumping >5A spikes through your system it is also putting a strain on all your house wiring - this can start fires now, or even in years time from damaged connections/junction behind your walls.

If blowing fuses then you have a short.
That means a join between Live and N or E.

Now I can only guess:
- L wire in Earth or
- Nail in Wire
- If it is okay when Switch wire is not there (ie swiched off) then badly connected Lamp.

You are now needing to check everything by sight looking for shorts, or better get a multimeter, or even better get an electriction.

I am not happy to suggest that you test by blowing the fuse as this is v dangerous.

SFK

 

[john wright]

Good advice SFK!

In truth i think it’s my lamp wiring.

Thanks again and yes no more fuse blowing. Reaching out to a local electrician now!

John

 

[john wright]

...yup! you’re right again.

earth had come loose in one of my lamps and was touching the blue/neutral wire/terminal. guess that was the problem right there.

j

 

[winston1]

An earth to neutral short will NOT blow a fuse with a bang, though it would trip an RCD. Are you sure your blue wire is a neutral? Hint, wires don't know what colour they are.

 

[john wright]

Hi Winston!

i understand what you’re saying re the colour of the sleeve, but i’m only connecting pendant lights and unless i’m mistaken the sleeve colour is irrelevant.

i’m connecting Blue-Neutral and Brown-Live with Yellow to Earth

Am i missing something?

John

 

[winston1]

You said an earth wire had touched a blue/neutral terminal causing a fuse to go with a bang. A neutral to earth short will not cause this, hence my suggestion your blue was not in fact a neutral.