Pesky PIR Light

Seen a couple of these do this. I assume it's the same as the dying light bulb taking out dimmer switches.

bulb pops, huge current pops the triac (or whatever is in these things).

It's dead dave...

:)

Darren

In message , The Medway Handyman writes

If it uses a triac to switch the lamp (which it sounds like it does) then that has probably failed short circuit when the lamp popped.

On Tue, 27 Mar 2007 20:17:31 GMT, "The Medway Handyman" mused:

Bin it.

Remove the PIR circuit and use it as an ordinary light in another location, or keep it in the comes-in-useful box.

Owain

Triac seems to be the problem then.

We get through loads of PIR light, bloody things never seem to last long - mind you we have a substation at the end of our cul de sac and our voltage is always high - we also get through lots of light bulbs.

I shall avoid the dimming ones from now on.

Thinking about it, I've changed about 6 PIR lights for customers in the past year.

Any suggestions for a make that will last more than 5 mins?

The dimming ones are a terrible waste of money

A low current fuse will sometimes save their bacon too, 2A is a good compromise between protection and robustness.

NT

Its an ex lantern! ;-)

(The standalone PIRs from screwfix I fitted years ago are working perfectly. The PIR half lanterns I got from TLC were also rather nice)

|!Hi |! |!We have a PIR lantern outside the front door. Bulb went so I changed it, |!now the pesky thing stays on all the time, even in daylight - can't find the |!destructions either. |! |!It is (was) one of those that comes on at a low level after dusk, then turns |!to full power when the detector is triggered, then back to low level after a |!short time. |! |!Tried turning in on during the day, turn on/off quickly, slowly, whatever. |! |!Any ideas before I bin it & buy a new one?

Both PIRs I have installed have failed within a year, added to the lamp failures. So maybe one has to live with the cost of a new one every year or so :-(.

A higher current triac will also have a higher holding current, which relates to the minimum load a dimmer can drive. Often that's around 40W, and will increase roughly proportionally with a higher current triac. (This will not be an issue with dimmers designed for use with LV halogen lamps, but they're more expensive. It may not be an issue with a PIR -- check if it quotes a minimum load.)

So far, I've found a 3A MCB has protected some rather expensive X10 dimmers. 2A fuses don't -- many dimmers have them inside anyway. They often blow together with the triac.

In a circuit I designed which uses MOSFETs rather than triacs to switch mains, I have used a very fast blow fuse, but you won't find that in cheap dimmers, and it would blow almost every time a bulb blew (in this case, my load isn't bulbs).

I've installed a number of relay based ones over the last ~12 years, and none have failed. They are all separate units from the lights temselves. In most cases, I find the light itself is in the wrong position for its PIR.