Another LED/CCFL question - exterior "sealed" lamps

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Fred99

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#143503 17-Apr-2014 07:48

I've got some exterior sealed (glass globe type) lamp holders under the wooden eaves of the house, wired up with a separate PIR detector. The (incandescent) bulb in one of them has blown - time to replace it.
At the local shop, there are Philips brand CCFL and LED lamps on the shelf. The CCFL packaging states "must not be used on electronically switched circuits". The LED packaging states "must not be used in sealed lampholders". The lampholders probably have a maximum wattage rating of 75w. I don't want the PIR detector to blow - not very keen on creating a fire risk either. Should I just stick with incandescent bulbs?

Dynamic

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#1026586 17-Apr-2014 08:40

I suspect the 'electronically switched circuits' means a dimmer that works by rapidly switching the power to the bulb on and off (dimming by reducing the time the bulb has power, not by reducing the voltage).

I suspect the 'sealed lampholders' relates to heat - i.e. the heat from the LED and its circuitry needs to be able to dissipate. Given the heat from the LED is going to be substantially less than an incandescent, then I think you should be fine, provided there is no possibility of the LED bulb getting wet.

I've put LED replacements for incandescent bulbs into the kids bedside lights recently to reduce the chance of burn or fire. Love them. I expect to replace CCFL's in the house with LEDs as they die.

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Fred99

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#1026786 17-Apr-2014 11:22

Thanks. Pretty sure that the Philips CCFLs have "not dimmable" as well as "not for use with electronically switched circuits" marked on them. I don't want to kill the PIR detector - it was expensive, isn't easy to get at, and took a while to get the sensitivity set up an d the direction set up on the mount - many trips up and down a ladder to get things "just right". There seem to be two firm opinions about this - "don't use CCFLs with PIRs" and "don't listen to people who say don't use CCFLs with PIRs".
As for LEDs - I was surprised to see the warning about not using them in sealed enclosures. Do they have overheat protection - like a polyfuse etc on the heatsink?

Dynamic

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#1026825 17-Apr-2014 12:30

Personally I would just throw in an LED so you won't have to touch it for years to come. It's going to be either on for only a few minutes, or even if you leave it on overnight for any reason it's in a cold environment (at night).

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Mike

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Niel

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#1027022 17-Apr-2014 17:22

A PIR is not the electronically switching device they talk of. It uses a mechanical relay controlled by electronic circuitry, not a solid state electronic relay controlled by electronic circuitry. It gets hard for manufacturers to get the wording right as well as suitable for general public to understand.

LED should be fine, and being in a sealed fitting intended for a 75W hot globe, even if the ~10W LED would get too hot and fail then there is virtually no chance of the house catching fire. Don;t bother with CCFL even if it can be used in a sealed fitting, it is too cold when you need it in winter and so takes ages to warm up.

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Fred99

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#1027836 19-Apr-2014 19:40

OK - I put a 10W LED in it. The globe unit is sealed, but the lamp bayonet holder is ceramic and there's nothing flammable in there.
The (Philips brand) LED lamp is fully sealed - no vents. It seems strange that there's a clear instruction on the box to not use it in a sealed lampholder when it replaces an incandescent with almost 10x the heat generation.
It works well - claimed to be about = 75W incandescent - that's easily believable.
There's no relay on the PIR board (I'm sure of this) - it seems to be triac switched, so it is "electronically switched". Perhaps some circuits do have a relay. Perhaps that's why some advice is that PIR detectors are fine with CCFLs, other advice is that they are not. Will the load from a CCFL actually kill a triac? I don't know.

Niel

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#1027907 19-Apr-2014 20:40

An LED bulb does not need vents, it just needs the surface to radiate heat. I believe the issue with sealed fittings if greater in warmer climates, not NZ, and will certainly be much less of an issue if used only at night when it is cooler. The difference between LEDs and incandescence is that LEDs need to be cool to get a long life. The manufacturer will not claim a long LED life and say it is fine to run the bulb in a sealed fitting when they have no control over the ambient temperature. Worst that will happen is probably a reduced life.

I am surprised the PIR does not use a relay, guess the design got updated or silicone became cheaper or they could not fit a relay in a small housing. The main reason for using relays is because it is much easier to pass electrical compliance testing, and traditionally was also much cheaper.

A CCFL should not kill a triac, but a dimmer will chop up the mains and put excessive ripple/stress on the electronic circuit in a CCFL/LED fitting unless it is designed for it.

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Fred99

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#1027921 19-Apr-2014 21:03

Good - that makes sense about heat / LED life. I have the timer set to about 5 mins - it's seldom if ever on for longer than that.
Actually the PIR detector is quite old (10+ years). I think the cheap "combo PIR detector / exterior lights" use relays - you can hear them click.

Fred99

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#1027986 19-Apr-2014 23:18

Niel:

A CCFL should not kill a triac, but a dimmer will chop up the mains and put excessive ripple/stress on the electronic circuit in a CCFL/LED fitting unless it is designed for it.

OK. Now I think I've got to the bottom of this as it's been bugging me...
The triac itself should be okay from the inductive load, but there's a definite possibility that the PIR control circuit (rather than the triac) could be fried by a voltage spike.
So they could use an (opto-coupled triac) SSR these days instead of an (electrically coupled) triac to solve that potential issue. Safer - except that both triac and SSR would probably fail-closed, but a mechanical relay is usually fail-open.