Replacement outdoor PIR

[Max Warren]

Hi all,

I had a very old outdoor PIR (Smiths, no model number) connected an LED floodlight, which is also linked to a one way switch. The PIR seemed to have failed as the light only flashed on when it detected movement (no ability to adjust time on).

I have got a Knightsbridge OS001 to replace and have done so with the wiring like for like. However, the issue I'm having is that the light stays on (in daylight) at half brightness at all times. When I use the switch to override in the on position the brightness increases, and reduces again when I turn it off. I have tried flicking the switch off a few times to push the PIR into auto mode, to no avail.

When I take the PIR face off of its backing, the LED light goes off and still responds to the switch.

Any ideas what I've done wrong here? Thanks!

 

[Taylortwocities]

It wont go into auto mode unless its dark, or if you have selected daytime operation.

Your light at half brightness may be because of induced voltages. You may need to install a snubber.

 

[oldbutnotdead]

How powerful is your floodlight? That detector has a max power rating of 200-odd watts which makes me think there's solid state switching and there may be a minimum load

 

[Max Warren]

How powerful is your floodlight? That detector has a max power rating of 200-odd watts which makes me think there's solid state switching and there may be a minimum load

Its a 30w LED, I see the PIR has a max 225w but no minimum is stated that I can see

 

[oldbutnotdead]

Its a 30w LED, I see the PIR has a max 225w but no minimum is stated that I can see

Try a heavier load (60w light bulb would be ideal if you had such a thing lying around)

 

[Max Warren]

Try a heavier load (60w light bulb would be ideal if you had such a thing lying around)

Gave this a go with a 50w LED and the same outcome

 

[oldbutnotdead]

Gave this a go with a 50w LED and the same outcome

Oh well there's my theory down the toilet.

 

[Taylortwocities]

Oh well there's my theory down the toilet.

Not necessarily. A “50watt LED” still has a very low operating current.
@Max Warren you were asked to

Try a heavier load (60w light bulb would be ideal if you had such a thing lying around)

he means an old style filament light bulb. Not an LED.

And, do you really mean 50 watt LED?
That sort of thing is used to light up a whole tennis court!

 

[Max Warren]

Not necessarily. A “50watt LED” still has a very low operating current.
@Max Warren you were asked to

he means an old style filament light bulb. Not an LED.

And, do you really mean 50 watt LED?
That sort of thing is used to light up a whole tennis court!

Will try a filament bulb instead

 

[ericmark]

I found with my electronic switches that some bulbs worked, and others did not, these bulbs caused my problems, with the small one, tried a load capacitor which stopped them staying on dim, but in the end fitted the larger bulb which cured the problem of shimmer as well as staying on dim.

One of the larger bulbs failed, so I opened to see what was inside, the smoothing capacitor was nearly as big as the whole small bulb.

Best option is get an outside light with built in PIR then your sure they will work together, personally I have stopped using PIR's and use smart bulbs instead, and turn on outside lights from my phone when required.

 

[Rodders53]

I'd suggest contacting the Distributor https://www.mlaccessories.co.uk/ to see if they can advise. It may be faulty? That model PIR manual states 2000W incandescent, 1000W fluorescent and 225W LED. No minimum loads... But...

LEDS will light dim if an electronic switch allows some small current to pass. They can also light for other induced voltage reasons. So the LED load(make/designs) may also be relevant.
I 'inherited' a decorative 5-led luminaire in this house that glowed in the dark when off and needed a 'snubber' to stop it doing so. Probably voltage induced from nearby wires passing?

I have a PIR similar to this https://www.amazon.co.uk/dp/B07932DV4Y controlling a 20 Watt Osram LEDVance floodlight with no such issues though.

 

[oldbutnotdead]

How powerful is your floodlight? That detector has a max power rating of 200-odd watts which makes me think there's solid state switching and there may be a minimum load

Yeah I should have been more specific and advised a resistive load- didn't see the 2kw resistive max, if there is an SCR or big MOSFET or something in there then quite likely 60w resistive would still glow or flicker (from long experience with thyristor/triac dimmers and load lamps being required). The last standalone PIR I bought (Screwfix LAP I think) had a nice old-fashioned relay in it

 

[Max Warren]

Manufacturer has advised there is no min load. The output from the OS001 is via a relay, it is on or off (on activation) and the relay contacts are rated to switch 225Watts of LED Load. So the half brightness state in auto mode remains a mystery.

 

[oldbutnotdead]

Manufacturer has advised there is no min load. The output from the OS001 is via a relay, it is on or off (on activation) and the relay contacts are rated to switch 225Watts of LED Load. So the half brightness state in auto mode remains a mystery.

Fair enough. Sounds like a cabling issue. You haven't done something random with the connections? Your switch- is it 3 position or 2 position? (For on/off/auto). Does that Knightsbridge box actually support the old 'switch off and on quickly' to latch on?

 

[Taylortwocities]

As above, if you have an LED that is dim when it should be off then you need a snubber across the lamp.
One of these should do you

PMR209MB5470M100R30 (0.047UF/100R) EVOX RIFA CLASS X2 CAP | eBay

(0.047UF/47R) EVOX RIFA CLASS X2 CAP. Manufacturer Part Number: PMR209MB5470M.

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